[v1,1/7] v4l: add videobuf2 Video for Linux 2 driver framework
Commit Message
Videobuf2 is a Video for Linux 2 API-compatible driver framework for
multimedia devices. It acts as an intermediate layer between userspace
applications and device drivers. It also provides low-level, modular
memory management functions for drivers.
Videobuf2 eases driver development, reduces drivers' code size and aids in
proper and consistent implementation of V4L2 API in drivers.
Videobuf2 memory management backend is fully modular. This allows custom
memory management routines for devices and platforms with non-standard
memory management requirements to be plugged in, without changing the
high-level buffer management functions and API.
The framework provides:
- implementations of streaming I/O V4L2 ioctls and file operations
- high-level video buffer, video queue and state management functions
- video buffer memory allocation and management
Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
---
drivers/media/video/Kconfig | 3 +
drivers/media/video/Makefile | 2 +
drivers/media/video/videobuf2-core.c | 1457 ++++++++++++++++++++++++++++++++++
include/media/videobuf2-core.h | 337 ++++++++
4 files changed, 1799 insertions(+), 0 deletions(-)
create mode 100644 drivers/media/video/videobuf2-core.c
create mode 100644 include/media/videobuf2-core.h
Comments
Em 09-09-2010 06:19, Pawel Osciak escreveu:
> Videobuf2 is a Video for Linux 2 API-compatible driver framework for
> multimedia devices. It acts as an intermediate layer between userspace
> applications and device drivers. It also provides low-level, modular
> memory management functions for drivers.
>
> Videobuf2 eases driver development, reduces drivers' code size and aids in
> proper and consistent implementation of V4L2 API in drivers.
>
> Videobuf2 memory management backend is fully modular. This allows custom
> memory management routines for devices and platforms with non-standard
> memory management requirements to be plugged in, without changing the
> high-level buffer management functions and API.
>
> The framework provides:
> - implementations of streaming I/O V4L2 ioctls and file operations
> - high-level video buffer, video queue and state management functions
> - video buffer memory allocation and management
>
> Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
> drivers/media/video/Kconfig | 3 +
> drivers/media/video/Makefile | 2 +
> drivers/media/video/videobuf2-core.c | 1457 ++++++++++++++++++++++++++++++++++
> include/media/videobuf2-core.h | 337 ++++++++
> 4 files changed, 1799 insertions(+), 0 deletions(-)
> create mode 100644 drivers/media/video/videobuf2-core.c
> create mode 100644 include/media/videobuf2-core.h
>
> diff --git a/drivers/media/video/Kconfig b/drivers/media/video/Kconfig
> index f6e4d04..5764443 100644
> --- a/drivers/media/video/Kconfig
> +++ b/drivers/media/video/Kconfig
> @@ -48,6 +48,9 @@ config VIDEO_TUNER
> config V4L2_MEM2MEM_DEV
> tristate
> depends on VIDEOBUF_GEN
> +config VIDEOBUF2_CORE
> + tristate
> +
>
> #
> # Multimedia Video device configuration
> diff --git a/drivers/media/video/Makefile b/drivers/media/video/Makefile
> index 40f98fb..e66f53b 100644
> --- a/drivers/media/video/Makefile
> +++ b/drivers/media/video/Makefile
> @@ -117,6 +117,8 @@ obj-$(CONFIG_VIDEOBUF_VMALLOC) += videobuf-vmalloc.o
> obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
> obj-$(CONFIG_VIDEO_BTCX) += btcx-risc.o
>
> +obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
> +
> obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
>
> obj-$(CONFIG_VIDEO_M32R_AR_M64278) += arv.o
> diff --git a/drivers/media/video/videobuf2-core.c b/drivers/media/video/videobuf2-core.c
> new file mode 100644
> index 0000000..ed4b665
> --- /dev/null
> +++ b/drivers/media/video/videobuf2-core.c
> @@ -0,0 +1,1457 @@
> +/*
> + * videobuf2-core.c - V4L2 driver helper framework
> + *
> + * Copyright (C) 2010 Samsung Electronics
> + *
> + * Author: Pawel Osciak <p.osciak@samsung.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/mm.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/sched.h>
> +#include <linux/err.h>
> +#include <linux/poll.h>
> +
> +#include <media/videobuf2-core.h>
> +
> +static int debug;
> +module_param(debug, int, 0644);
> +
> +#define dprintk(level, fmt, arg...) \
> + do { \
> + if (debug >= level) \
> + printk(KERN_DEBUG "vb2: " fmt, ## arg); \
> + } while (0)
> +
> +#define mem_ops(q, plane) ((q)->alloc_ctx[plane]->mem_ops)
> +
> +#define call_memop(q, plane, op, args...) \
> + ((q)->alloc_ctx[plane]->mem_ops->op) ? \
> + ((q)->alloc_ctx[plane]->mem_ops->op(args)) : 0
> +
> +
> +/**
> + * __vb2_buf_mem_alloc() - allocate video memory for the given buffer
> + */
> +static int __vb2_buf_mem_alloc(struct vb2_buffer *vb,
> + unsigned long *plane_sizes)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + void *mem_priv;
> + int plane;
> +
> + /* Allocate memory for all planes in this buffer */
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + mem_priv = call_memop(q, plane, alloc, q->alloc_ctx[plane],
> + plane_sizes[plane]);
> + if (!mem_priv)
> + goto free;
> +
> + /* Associate allocator private data with this plane */
> + vb->planes[plane].mem_priv = mem_priv;
> + vb->v4l2_planes[plane].length = plane_sizes[plane];
> + }
> +
> + return 0;
> +free:
> + /* Free already allocated memory if one of the allocations failed */
> + for (; plane > 0; --plane)
> + call_memop(q, plane, put, vb->planes[plane - 1].mem_priv);
> +
> + return -ENOMEM;
> +}
> +
> +/**
> + * __vb2_buf_mem_free() - free memory of the given buffer
> + */
> +static void __vb2_buf_mem_free(struct vb2_buffer *vb)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + unsigned int plane;
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + call_memop(q, plane, put, vb->planes[plane].mem_priv);
> + dprintk(3, "Freed plane %d of buffer %d\n",
> + plane, vb->v4l2_buf.index);
> + }
> +}
> +
> +/**
> + * __vb2_buf_userptr_put() - release userspace memory associated associated
> + * with a USERPTR buffer
> + */
> +static void __vb2_buf_userptr_put(struct vb2_buffer *vb)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + unsigned int plane;
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + call_memop(q, plane, put_userptr, vb->planes[plane].mem_priv);
> + vb->planes[plane].mem_priv = NULL;
> + }
> +}
> +
> +/**
> + * __setup_offsets() - setup unique offsets ("cookies") for every plane in
> + * every buffer on the queue
> + */
> +static void __setup_offsets(struct vb2_queue *q)
> +{
> + unsigned int buffer, plane;
> + struct vb2_buffer *vb;
> + unsigned long off = 0;
> +
> + for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> + vb = q->bufs[buffer];
> + if (!vb)
> + continue;
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + vb->v4l2_planes[plane].m.mem_offset = off;
> +
> + dprintk(3, "Buffer %d, plane %d offset 0x%08lx\n",
> + buffer, plane, off);
> +
> + off += vb->v4l2_planes[plane].length;
> + off = PAGE_ALIGN(off);
> + }
> + }
> +}
> +
> +/**
> + * __vb2_queue_alloc() - allocate videobuf buffer structures and (for MMAP type)
> + * video buffer memory for all buffers/planes on the queue and initializes the
> + * queue
> + *
> + * Returns the number of buffers successfully allocated.
> + */
> +static int __vb2_queue_alloc(struct vb2_queue *q, enum v4l2_memory memory,
> + unsigned int num_buffers, unsigned int num_planes)
> +{
> + unsigned long plane_sizes[VIDEO_MAX_PLANES];
> + unsigned int buffer, plane;
> + struct vb2_buffer *vb;
> + int ret;
> +
> + /* Get requested plane sizes from the driver */
> + for (plane = 0; plane < num_planes; ++plane) {
> + ret = q->ops->plane_setup(q, plane, &plane_sizes[plane]);
> + if (ret) {
> + dprintk(1, "Plane setup failed\n");
> + return ret;
> + }
> + }
> +
> + for (buffer = 0; buffer < num_buffers; ++buffer) {
> + /* Allocate videobuf buffer structures */
> + vb = kzalloc(sizeof(struct vb2_buffer), GFP_KERNEL);
> + if (!vb) {
> + dprintk(1, "Memory alloc for buffer struct failed\n");
> + break;
> + }
> +
> + /* Length stores number of planes for multiplanar buffers */
> + if (V4L2_TYPE_IS_MULTIPLANAR(q->type))
> + vb->v4l2_buf.length = num_planes;
> +
> + vb->state = VB2_BUF_STATE_DEQUEUED;
> + vb->vb2_queue = q;
> + vb->num_planes = num_planes;
> + vb->v4l2_buf.index = buffer;
> + vb->v4l2_buf.type = q->type;
> + vb->v4l2_buf.memory = memory;
> +
> + /* Allocate video buffer memory for the MMAP type */
> + if (memory == V4L2_MEMORY_MMAP) {
> + ret = __vb2_buf_mem_alloc(vb, plane_sizes);
> + if (ret) {
> + dprintk(1, "Failed allocating memory for "
> + "buffer %d\n", buffer);
> + kfree(vb);
> + break;
> + }
> + /*
> + * Call the driver-provided buffer initialization
> + * callback, if given. An error in initialization
> + * results in queue setup failure.
> + */
> + if (q->ops->buf_init) {
> + ret = q->ops->buf_init(vb);
> + if (ret) {
> + dprintk(1, "Buffer %d %p initialization"
> + " failed\n", buffer, vb);
> + __vb2_buf_mem_free(vb);
> + kfree(vb);
> + break;
> + }
> + }
> + }
> +
> + q->bufs[buffer] = vb;
> + }
> +
> + q->num_buffers = buffer;
> +
> + __setup_offsets(q);
> +
> + dprintk(1, "Allocated %d buffers, %d plane(s) each\n",
> + q->num_buffers, num_planes);
> +
> + return buffer;
> +}
> +
> +/**
> + * __vb2_free_mem() - release all video buffer memory for a given queue
> + */
> +static void __vb2_free_mem(struct vb2_queue *q)
> +{
> + unsigned int buffer;
> + struct vb2_buffer *vb;
> +
> + for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> + vb = q->bufs[buffer];
> + if (!vb)
> + continue;
> +
> + /* Free MMAP buffers or release USERPTR buffers */
> + if (q->memory == V4L2_MEMORY_MMAP)
> + __vb2_buf_mem_free(vb);
> + else
> + __vb2_buf_userptr_put(vb);
> + }
> +}
> +
> +/**
> + * __vb2_queue_free() - free the queue - video memory and related information
> + * and return the queue to an uninitialized state
> + */
> +static int __vb2_queue_free(struct vb2_queue *q)
> +{
> + unsigned int buffer;
> +
> + /* Call driver-provided cleanup function for each buffer, if provided */
> + if (q->ops->buf_cleanup) {
> + for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> + if (NULL == q->bufs[buffer])
> + continue;
> + q->ops->buf_cleanup(q->bufs[buffer]);
> + }
> + }
> +
> + /* Release video buffer memory */
> + __vb2_free_mem(q);
> +
> + /* Free videobuf buffers */
> + for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> + if (NULL == q->bufs[buffer])
> + continue;
> + kfree(q->bufs[buffer]);
> + q->bufs[buffer] = NULL;
> + }
> +
> + q->num_buffers = 0;
> + q->memory = 0;
> +
> + return 0;
> +}
> +
> +/**
> + * __verify_planes_array() - verify that the planes array passed in struct
> + * v4l2_buffer from userspace can be safely used
> + */
> +static int __verify_planes_array(struct vb2_buffer *vb, struct v4l2_buffer *b)
> +{
> + /* Is memory for copying plane information present? */
> + if (NULL == b->m.planes) {
> + dprintk(1, "Multi-planar buffer passed but "
> + "planes array not provided\n");
> + return -EINVAL;
> + }
> +
> + if (b->length < vb->num_planes || b->length > VIDEO_MAX_PLANES) {
> + dprintk(1, "Incorrect planes array length, "
> + "expected %d, got %d\n", vb->num_planes, b->length);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * __fill_v4l2_buffer() - fill in a struct v4l2_buffer with information to be
> + * returned to userspace
> + */
> +static int __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + int ret = 0;
> +
> + /* Copy back data such as timestamp, input, etc. */
> + memcpy(b, &vb->v4l2_buf, offsetof(struct v4l2_buffer, m));
> + b->input = vb->v4l2_buf.input;
> + b->reserved = vb->v4l2_buf.reserved;
> +
> + if (V4L2_TYPE_IS_MULTIPLANAR(q->type)) {
> + ret = __verify_planes_array(vb, b);
> + if (ret)
> + return ret;
> +
> + /*
> + * Fill in plane-related data if userspace provided an array
> + * for it. The memory and size is verified above.
> + */
> + memcpy(b->m.planes, vb->v4l2_planes,
> + b->length * sizeof(struct v4l2_plane));
> + } else {
> + /*
> + * We use length and offset in v4l2_planes array even for
> + * single-planar buffers, but userspace does not.
> + */
> + b->length = vb->v4l2_planes[0].length;
> + if (q->memory == V4L2_MEMORY_MMAP)
> + b->m.offset = vb->v4l2_planes[0].m.mem_offset;
> + }
> +
> + b->flags = 0;
> +
> + switch (vb->state) {
> + case VB2_BUF_STATE_QUEUED:
> + case VB2_BUF_STATE_ACTIVE:
> + b->flags |= V4L2_BUF_FLAG_QUEUED;
> + break;
> + case VB2_BUF_STATE_ERROR:
> + b->flags |= V4L2_BUF_FLAG_ERROR;
> + /* fall through */
> + case VB2_BUF_STATE_DONE:
> + b->flags |= V4L2_BUF_FLAG_DONE;
> + break;
> + case VB2_BUF_STATE_DEQUEUED:
> + /* nothing */
> + break;
> + }
> +
> + if (vb->num_planes_mapped == vb->num_planes)
> + b->flags |= V4L2_BUF_FLAG_MAPPED;
> +
> + return ret;
> +}
> +
> +/**
> + * vb2_querybuf() - query video buffer information
> + * @q: videobuf queue
> + * @b: buffer struct passed from userspace to vidioc_querybuf handler
> + * in driver
> + *
> + * Should be called from vidioc_querybuf ioctl handler in driver.
> + * This function will verify the passed v4l2_buffer structure and fill the
> + * relevant information for the userspace.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_querybuf handler in driver.
> + */
> +int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
> +{
> + struct vb2_buffer *vb;
> + int ret = -EINVAL;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (b->type != q->type) {
> + dprintk(1, "querybuf: wrong buffer type\n");
> + goto done;
> + }
> +
> + if (b->index >= q->num_buffers) {
> + dprintk(1, "querybuf: buffer index out of range\n");
> + goto done;
> + }
> + vb = q->bufs[b->index];
> + if (NULL == vb) {
> + /* Should never happen */
> + dprintk(1, "querybuf: no such buffer\n");
> + goto done;
> + }
> +
> + ret = __fill_v4l2_buffer(vb, b);
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL(vb2_querybuf);
> +
> +/**
> + * __verify_userptr_ops() - verify that all memory operations required for
> + * USERPTR queue type have been provided
> + */
> +static int __verify_userptr_ops(struct vb2_queue *q, unsigned int num_planes)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < num_planes; ++i)
> + if (!mem_ops(q, i)->get_userptr || !mem_ops(q, i)->put_userptr)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +/**
> + * __verify_mmap_ops() - verify that all memory operations required for
> + * MMAP queue type have been provided
> + */
> +static int __verify_mmap_ops(struct vb2_queue *q, unsigned int num_planes)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < num_planes; ++i)
> + if (!mem_ops(q, i)->alloc || !mem_ops(q, i)->put
> + || !mem_ops(q, i)->mmap)
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +/**
> + * __buffers_in_use() - return true if any buffers on the queue are in use and
> + * the queue cannot be freed (by the means of REQBUFS(0)) call
> + */
> +static bool __buffers_in_use(struct vb2_queue *q)
> +{
> + unsigned int buffer, plane;
> + struct vb2_buffer *vb;
> +
> + for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> + vb = q->bufs[buffer];
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + /*
> + * If num_users() has not been provided, apparently
> + * nobody cares.
> + */
> + if (!mem_ops(q, plane)->num_users)
> + continue;
> +
> + /*
> + * If num_users() returns more than 1, we are not the
> + * only user of the plane's memory.
> + */
> + if (call_memop(q, plane, num_users,
> + vb->planes[plane].mem_priv) > 1)
> + return true;
> + }
> + }
> +
> + return false;
> +}
> +
> +/**
> + * vb2_reqbufs() - Initiate streaming
> + * @q: videobuf2 queue
> + * @req: struct passed from userspace to vidioc_reqbufs handler in driver
> + *
> + * Should be called from vidioc_reqbufs ioctl handler of a driver.
> + * This function:
> + * 1) verifies streaming parameters passed from the userspace,
> + * 2) sets up the queue,
> + * 3) negotiates number of buffers and planes per buffer with the driver
> + * to be used during streaming,
> + * 4) allocates internal buffer structures (struct vb2_buffer), according to
> + * the agreed parameters,
> + * 5) for MMAP memory type, allocates actual video memory, using the
> + * memory handling/allocation routines provided during queue initialization
> + *
> + * If req->count is 0, all the memory will be freed instead.
> + * If the queue has been allocated previously (by a previous vb2_reqbufs) call
> + * and the queue is not busy, memory will be reallocated.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_reqbufs handler in driver.
> + */
> +int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
> +{
> + unsigned int num_buffers, num_planes;
> + int ret = 0;
> +
> + if (req->memory != V4L2_MEMORY_MMAP
> + && req->memory != V4L2_MEMORY_USERPTR) {
> + dprintk(1, "reqbufs: unsupported memory type\n");
> + return -EINVAL;
Hmm... V4L2_MEMORY_OVERLAY is not supported... this means that videobuf2 cannot replace
videobuf1 for some drivers...
> + }
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (req->type != q->type) {
> + dprintk(1, "reqbufs: queue type invalid\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + if (q->streaming) {
> + dprintk(1, "reqbufs: streaming active\n");
> + ret = -EBUSY;
> + goto end;
> + }
> +
> + if (req->count == 0) {
> + /* Free/release memory for count = 0, but only if unused */
> + if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) {
> + dprintk(1, "reqbufs: memory in use, cannot free\n");
> + ret = -EBUSY;
> + goto end;
> + }
> +
> + ret = __vb2_queue_free(q);
> + goto end;
> + }
> +
> + if (q->num_buffers != 0) {
> + /*
> + * We already have buffers allocated, so a reallocation is
> + * required, but only if the buffers are not in use.
> + */
> + if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) {
> + dprintk(1, "reqbufs: memory in use, "
> + "cannot reallocate\n");
> + ret = -EBUSY;
> + goto end;
> + }
> +
> + ret = __vb2_queue_free(q);
> + if (ret)
> + goto end;
> + }
> +
> + num_buffers = min_t(unsigned int, req->count, VIDEO_MAX_FRAME);
> +
> + /* Ask the driver how many buffers and planes per buffer it requires */
> + ret = q->ops->queue_negotiate(q, &num_buffers, &num_planes);
> + if (ret)
> + goto end;
> +
> + /*
> + * Make sure all the required memory ops for given memory type
> + * are available.
> + */
> + if (req->memory == V4L2_MEMORY_MMAP
> + && __verify_mmap_ops(q, num_planes)) {
> + dprintk(1, "reqbufs: MMAP for current setup unsupported\n");
> + ret = -EINVAL;
> + goto end;
> + } else if (req->memory == V4L2_MEMORY_USERPTR
> + && __verify_userptr_ops(q, num_planes)) {
> + dprintk(1, "reqbufs: USERPTR for current setup unsupported\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + /* Finally, allocate buffers and video memory */
> + ret = __vb2_queue_alloc(q, req->memory, num_buffers, num_planes);
> + if (ret < 0) {
> + dprintk(1, "Memory allocation failed with error: %d\n", ret);
> + } else {
> + /*
> + * Return the number of successfully allocated buffers
> + * to the userspace.
> + */
> + req->count = ret;
> + ret = 0;
> + }
> +
> + q->memory = req->memory;
> +
> +end:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_reqbufs);
> +
> +/**
> + * vb2_plane_vaddr() - Return a kernel virtual address of a given plane
> + * @vb: vb2_buffer to which the plane in question belongs to
> + * @plane_no: plane number for which the address is to be returned
> + *
> + * This function returns a kernel virtual address of a given plane if
> + * such a mapping exist, NULL otherwise.
> + */
> +void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> +
> + if (plane_no > vb->num_planes)
> + return NULL;
> +
> + return call_memop(q, plane_no, vaddr, vb->planes[plane_no].mem_priv);
> +
> +}
> +EXPORT_SYMBOL_GPL(vb2_plane_vaddr);
> +
> +/**
> + * vb2_plane_paddr() - Return the physical address of a given plane
> + * @vb: vb2_buffer to which the plane in question belongs to
> + * @plane_no: plane number for which the address is to be returned
> + *
> + * This function returns a physical address of a given plane if available,
> + * NULL otherwise.
> + */
> +unsigned long vb2_plane_paddr(struct vb2_buffer *vb, unsigned int plane_no)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> +
> + if (plane_no > vb->num_planes)
> + return 0UL;
> +
> + return call_memop(q, plane_no, paddr, vb->planes[plane_no].mem_priv);
> +}
> +EXPORT_SYMBOL_GPL(vb2_plane_paddr);
> +
> +/**
> + * vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
> + * @vb: vb2_buffer returned from the driver
> + * @state: either VB2_BUF_STATE_DONE if the operation finished successfully
> + * or VB2_BUF_STATE_ERROR if the operation finished with an error
> + *
> + * This function should be called by the driver after a hardware operation on
> + * a buffer is finished and the buffer may be returned to userspace. The driver
> + * cannot use this buffer anymore until it is queued back to it by videobuf
> + * by the means of buf_queue callback. Only buffers previously queued to the
> + * driver by buf_queue can be passed to this function.
> + */
> +void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + unsigned long flags;
> +
> + if (vb->state != VB2_BUF_STATE_ACTIVE)
> + return;
> +
> + if (state != VB2_BUF_STATE_DONE && state != VB2_BUF_STATE_ERROR)
> + return;
> +
> + dprintk(4, "Done processing on buffer %d, state: %d\n",
> + vb->v4l2_buf.index, vb->state);
> +
> + /* Add the buffer to the done buffers list */
> + spin_lock_irqsave(&q->done_lock, flags);
> + vb->state = state;
> + list_add_tail(&vb->done_entry, &q->done_list);
> + spin_unlock_irqrestore(&q->done_lock, flags);
> +
> + /* Inform any processes that may be waiting for buffers */
> + wake_up_interruptible(&q->done_wq);
> +}
> +EXPORT_SYMBOL_GPL(vb2_buffer_done);
> +
> +/**
> + * __fill_vb2_buffer() - fill a vb2_buffer with information provided in
> + * a v4l2_buffer by the userspace
> + */
> +static int __fill_vb2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b,
> + struct v4l2_plane *v4l2_planes)
> +{
> + unsigned int plane;
> + int ret;
> +
> + if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
> + /*
> + * Verify that the userspace gave us a valid array for
> + * plane information.
> + */
> + ret = __verify_planes_array(vb, b);
> + if (ret)
> + return ret;
> +
> + /* Fill in driver-provided information for OUTPUT types */
> + if (V4L2_TYPE_IS_OUTPUT(b->type)) {
> + /*
> + * Will have to go up to b->length when API starts
> + * accepting variable number of planes.
> + */
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + v4l2_planes[plane].bytesused =
> + b->m.planes[plane].bytesused;
> + v4l2_planes[plane].data_offset =
> + b->m.planes[plane].data_offset;
> + }
> + }
> +
> + if (b->memory == V4L2_MEMORY_USERPTR) {
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + v4l2_planes[plane].m.userptr =
> + b->m.planes[plane].m.userptr;
> + v4l2_planes[plane].length =
> + b->m.planes[plane].length;
> + }
> + }
> + } else {
> + /*
> + * Single-planar buffers do not use planes array,
> + * so fill in relevant v4l2_buffer struct fields instead.
> + * In videobuf we use our internal V4l2_planes struct for
> + * single-planar buffers as well, for simplicity.
> + */
> + if (V4L2_TYPE_IS_OUTPUT(b->type))
> + v4l2_planes[0].bytesused = b->bytesused;
> +
> + if (b->memory == V4L2_MEMORY_USERPTR) {
> + v4l2_planes[0].m.userptr = b->m.userptr;
> + v4l2_planes[0].length = b->length;
> + }
> + }
> +
> + vb->v4l2_buf.field = b->field;
> + vb->v4l2_buf.timestamp = b->timestamp;
> +
> + return 0;
> +}
> +
> +/**
> + * __qbuf_userptr() - handle qbuf of a USERPTR buffer
> + */
> +static int __qbuf_userptr(struct vb2_buffer *vb, struct v4l2_buffer *b)
> +{
> + struct v4l2_plane planes[VIDEO_MAX_PLANES];
> + struct vb2_queue *q = vb->vb2_queue;
> + void *mem_priv = NULL;
> + unsigned int plane;
> + int ret;
> +
> + /* Verify and copy relevant information provided by the userspace */
> + ret = __fill_vb2_buffer(vb, b, planes);
> + if (ret)
> + return ret;
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + /* Skip the plane if already verified */
> + if (vb->v4l2_planes[plane].m.userptr == planes[plane].m.userptr
> + && vb->v4l2_planes[plane].length == planes[plane].length)
> + continue;
> +
> + dprintk(3, "qbuf: userspace address for plane %d changed, "
> + "reacquiring memory\n", plane);
> +
> + /* Release previously acquired memory if present */
> + if (vb->planes[plane].mem_priv)
> + call_memop(q, plane, put_userptr,
> + vb->planes[plane].mem_priv);
> +
> + vb->planes[plane].mem_priv = NULL;
> +
> + /* Acquire each plane's memory */
> + if (mem_ops(q, plane)->get_userptr) {
> + mem_priv = mem_ops(q, plane)->get_userptr(
> + planes[plane].m.userptr,
> + planes[plane].length);
> + if (IS_ERR(mem_priv)) {
> + dprintk(1, "qbuf: failed acquiring userspace "
> + "memory for plane %d\n", plane);
> + goto err;
> + }
> +
> + vb->planes[plane].mem_priv = mem_priv;
> + }
> + }
> +
> + /*
> + * Call driver-specific initialization on the newly acquired buffer,
> + * if provided.
> + */
> + if (q->ops->buf_init) {
> + ret = q->ops->buf_init(vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer initialization failed\n");
> + goto err;
> + }
> + }
> +
> + /*
> + * Now that everything is in order, copy relevant information
> + * provided by userspace.
> + */
> + for (plane = 0; plane < vb->num_planes; ++plane)
> + vb->v4l2_planes[plane] = planes[plane];
> +
> + return 0;
> +err:
> + /* In case of errors, release planes that were already acquired */
> + for (; plane > 0; --plane) {
> + call_memop(q, plane, put_userptr,
> + vb->planes[plane - 1].mem_priv);
> + vb->planes[plane - 1].mem_priv = NULL;
> + }
> +
> + return ret;
> +}
> +
> +/**
> + * __qbuf_mmap() - handle qbuf of an MMAP buffer
> + */
> +static int __qbuf_mmap(struct vb2_buffer *vb, struct v4l2_buffer *b)
> +{
> + return __fill_vb2_buffer(vb, b, vb->v4l2_planes);
> +}
> +
> +/**
> + * __enqueue_in_driver() - enqueue a vb2_buffer in driver for processing
> + */
> +static void __enqueue_in_driver(struct vb2_buffer *vb)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + unsigned long flags;
> +
> + spin_lock_irqsave(q->drv_lock, flags);
> + vb->state = VB2_BUF_STATE_ACTIVE;
> + q->ops->buf_queue(vb);
> + spin_unlock_irqrestore(q->drv_lock, flags);
> +}
> +
> +/**
> + * vb2_qbuf() - Queue a buffer from userspace
> + * @q: videobuf2 queue
> + * @b: buffer structure passed from userspace to vidioc_qbuf handler
> + * in driver
> + *
> + * Should be called from vidioc_qbuf ioctl handler of a driver.
> + * This function:
> + * 1) verifies the passed buffer,
> + * 2) calls buf_prepare callback in the driver (if provided), in which
> + * driver-specific buffer initialization can be performed,
> + * 3) if streaming is on, queues the buffer in driver by the means of buf_queue
> + * callback for processing.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_qbuf handler in driver.
> + */
> +int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
> +{
> + struct vb2_buffer *vb;
> + int ret;
> +
> + mutex_lock(&q->vb_lock);
> +
> + ret = -EINVAL;
> + if (b->type != q->type) {
> + dprintk(1, "qbuf: invalid buffer type\n");
> + goto done;
> + }
> + if (b->index >= q->num_buffers) {
> + dprintk(1, "qbuf: buffer index out of range\n");
> + goto done;
> + }
> +
> + vb = q->bufs[b->index];
> + if (NULL == vb) {
> + /* Should never happen */
> + dprintk(1, "qbuf: buffer is NULL\n");
> + goto done;
> + }
> +
> + if (b->memory != q->memory) {
> + dprintk(1, "qbuf: invalid memory type\n");
> + goto done;
> + }
> +
> + if (vb->state != VB2_BUF_STATE_DEQUEUED) {
> + dprintk(1, "qbuf: buffer already in use\n");
> + goto done;
> + }
> +
> + if (q->memory == V4L2_MEMORY_MMAP)
> + ret = __qbuf_mmap(vb, b);
> + else if (q->memory == V4L2_MEMORY_USERPTR)
> + ret = __qbuf_userptr(vb, b);
> + if (ret)
> + goto done;
> +
> + if (q->ops->buf_prepare) {
> + ret = q->ops->buf_prepare(vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer preparation failed\n");
> + goto done;
> + }
> + }
> +
> + /*
> + * Add to the queued buffers list, a buffer will stay on it until
> + * dequeued in dqbuf.
> + */
> + list_add_tail(&vb->queued_entry, &q->queued_list);
> + vb->state = VB2_BUF_STATE_QUEUED;
> +
> + /*
> + * If already streaming, give the buffer to driver for processing.
> + * If not, the buffer will be given to driver on next streamon.
> + */
> + if (q->streaming)
> + __enqueue_in_driver(vb);
> +
> + dprintk(1, "qbuf of buffer %d succeeded\n", vb->v4l2_buf.index);
> + ret = 0;
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_qbuf);
> +
> +/**
> + * __vb2_wait_for_done_vb() - wait for a buffer to become available
> + * for dequeuing
> + *
> + * Will sleep if required for nonblocking == false.
> + */
> +static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
> +{
> + int retval = 0;
> +
> +checks:
> + if (!q->streaming) {
> + dprintk(1, "Streaming off, will not wait for buffers\n");
> + retval = -EINVAL;
> + goto end;
> + }
> +
> + /*
> + * Buffers may be added to vb_done_list without holding the vb_lock,
> + * but removal is performed only while holding both vb_lock and the
> + * vb_done_lock spinlock. Thus we can be sure that as long as we hold
> + * vb_lock, the list will remain not empty if this check succeeds.
> + */
> + if (list_empty(&q->done_list)) {
> + if (nonblocking) {
> + dprintk(1, "Nonblocking and no buffers to dequeue, "
> + "will not wait\n");
> + retval = -EAGAIN;
> + goto end;
> + }
> +
> + /*
> + * We are streaming and nonblocking, wait for another buffer to
> + * become ready or for streamoff. vb_lock is released to allow
> + * streamoff or qbuf to be called while waiting.
> + */
> + mutex_unlock(&q->vb_lock);
There's no mutex_lock before this call inside this function... It doesn't
seem to be a good idea to call it with a mutex locked, and having a unlock/lock
inside the fuction. The better would be to call it with mutex unlocked and let it
lock/unlock where needed.
> + /*
> + * Although the mutex is released here, we will be reevaluating
> + * both conditions again after reacquiring it.
> + */
> + dprintk(3, "Will sleep waiting for buffers\n");
> + retval = wait_event_interruptible(q->done_wq,
> + !list_empty(&q->done_list) || !q->streaming);
I think you could have a race condition here, as you're checking for list_empty
without a lock. The better approach would be to do something like:
static int vb2_is_videobuf_empty(struct vb2_queue *q)
{
int is_empty;
mutex_lock(&q->vb_lock);
is_empty = list_empty(&q->done_list);
mutex_unlock(&q->vb_lock);
return is_empty;
}
static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
{
...
retval = wait_event_interruptible(q->done_wq, vb2_is_videobuf_empty(q) || !q->streaming);
...
}
This way, you'll always have the mutex locked when checking for list empty.
Btw, shouldn't it be using, instead a spinlock?
To avoid needing to have a lock also for q->streaming, the better would be to define
it as atomic_t.
> + mutex_lock(&q->vb_lock);
> +
> + if (retval)
> + goto end;
> +
> + goto checks;
> + }
> +
> +end:
> + return retval;
> +}
> +
> +/**
> + * __vb2_get_done_vb() - get a buffer ready for dequeuing
> + *
> + * Will sleep if required for nonblocking == false.
> + */
> +static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer **vb,
> + int nonblocking)
> +{
> + unsigned long flags;
> + int ret = 0;
> +
> + /*
> + * Wait for at least one buffer to become available on the done_list.
> + */
> + ret = __vb2_wait_for_done_vb(q, nonblocking);
> + if (ret)
> + goto end;
> +
> + /*
> + * vb_lock has been held since we last verified that done_list is
> + * not empty, so no need for another list_empty(done_list) check.
> + */
> + spin_lock_irqsave(&q->done_lock, flags);
> + *vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
> + list_del(&(*vb)->done_entry);
> + spin_unlock_irqrestore(&q->done_lock, flags);
> +
> +end:
> + return ret;
> +}
> +
> +
> +/**
> + * vb2_dqbuf() - Dequeue a buffer to the userspace
> + * @q: videobuf2 queue
> + * @b: buffer structure passed from userspace to vidioc_dqbuf handler
> + * in driver
> + * @nonblocking: if true, this call will not sleep waiting for a buffer if no
> + * buffers ready for dequeuing are present. Normally the driver
> + * would be passing (file->f_flags & O_NONBLOCK) here
> + *
> + * Should be called from vidioc_dqbuf ioctl handler of a driver.
> + * This function:
> + * 1) verifies the passed buffer,
> + * 2) calls buf_finish callback in the driver (if provided), in which
> + * driver can perform any additional operations that may be required before
> + * returning the buffer to userspace, such as cache sync,
> + * 3) the buffer struct members are filled with relevant information for
> + * the userspace.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_dqbuf handler in driver.
> + */
> +int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking)
> +{
> + struct vb2_buffer *vb = NULL;
> + int ret;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (b->type != q->type) {
> + dprintk(1, "dqbuf: invalid buffer type\n");
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + ret = __vb2_get_done_vb(q, &vb, nonblocking);
> + if (ret < 0) {
> + dprintk(1, "dqbuf: error getting next done buffer\n");
> + goto done;
> + }
> +
> + if (q->ops->buf_finish) {
> + ret = q->ops->buf_finish(vb);
> + if (ret) {
> + dprintk(1, "dqbuf: buffer finish failed\n");
> + goto done;
> + }
> + }
> +
> + switch (vb->state) {
> + case VB2_BUF_STATE_DONE:
> + dprintk(3, "dqbuf: Returning done buffer\n");
> + break;
> + case VB2_BUF_STATE_ERROR:
> + dprintk(3, "dqbuf: Returning done buffer with errors\n");
> + break;
> + default:
> + dprintk(1, "dqbuf: Invalid buffer state\n");
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + /* Fill buffer information for the userspace */
> + __fill_v4l2_buffer(vb, b);
> + /* Remove from videobuf queue */
> + list_del(&vb->queued_entry);
> +
> + dprintk(1, "dqbuf of buffer %d, with state %d\n",
> + vb->v4l2_buf.index, vb->state);
> +
> + vb->state = VB2_BUF_STATE_DEQUEUED;
> +
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_dqbuf);
> +
> +/**
> + * vb2_streamon - start streaming
> + * @q: videobuf2 queue
> + * @type: type argument passed from userspace to vidioc_streamon handler
> + *
> + * Should be called from vidioc_streamon handler of a driver.
> + * This function:
> + * 1) verifies current state
> + * 2) starts streaming and passes any previously queued buffers to the driver
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_streamon handler in the driver.
> + */
> +int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
> +{
> + struct vb2_buffer *vb;
> + int ret = 0;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (type != q->type) {
> + dprintk(1, "streamon: invalid stream type\n");
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + if (q->streaming) {
> + dprintk(1, "streamon: already streaming\n");
> + ret = -EBUSY;
> + goto done;
> + }
> +
> + /*
> + * Cannot start streaming on an OUTPUT device if no buffers have
> + * been queued yet.
> + */
> + if (V4L2_TYPE_IS_OUTPUT(q->type)) {
> + if (list_empty(&q->queued_list)) {
> + dprintk(1, "streamon: no output buffers queued\n");
> + ret = -EINVAL;
> + goto done;
> + }
> + }
> +
> + q->streaming = 1;
> +
> + /*
> + * If any buffers were queued before streamon,
> + * we can now pass them to driver for processing.
> + */
> + list_for_each_entry(vb, &q->queued_list, queued_entry)
> + __enqueue_in_driver(vb);
> +
> + dprintk(3, "Streamon successful\n");
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_streamon);
> +
> +/**
> + * __vb2_queue_cancel() - cancel and stop (pause) streaming
> + *
> + * Removes all queued buffers from driver's queue and all buffers queued by
> + * userspace from videobuf's queue. Returns to state after reqbufs.
> + */
> +static void __vb2_queue_cancel(struct vb2_queue *q)
> +{
> + unsigned long flags = 0;
> + int i;
> +
> + q->streaming = 0;
> +
> + /*
> + * Remove buffers from driver's queue. If a hardware operation
> + * is currently underway, drv_lock should be claimed and we will
> + * have to wait for it to finish before taking back buffers.
> + */
> + spin_lock_irqsave(q->drv_lock, flags);
> + for (i = 0; i < q->num_buffers; ++i) {
> + if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
> + list_del(&q->bufs[i]->drv_entry);
> + q->bufs[i]->state = VB2_BUF_STATE_DEQUEUED;
> + }
> + spin_unlock_irqrestore(q->drv_lock, flags);
> +
> + /*
> + * Remove all buffers from videobuf's list...
> + */
> + INIT_LIST_HEAD(&q->queued_list);
> + /*
> + * ...and done list; userspace will not receive any buffers it
> + * has not already dequeued before initiating cancel.
> + */
> + INIT_LIST_HEAD(&q->done_list);
> + wake_up_interruptible_all(&q->done_wq);
> +}
> +
> +/**
> + * vb2_streamoff - stop streaming
> + * @q: videobuf2 queue
> + * @type: type argument passed from userspace to vidioc_streamoff handler
> + *
> + * Should be called from vidioc_streamoff handler of a driver.
> + * This function:
> + * 1) verifies current state,
> + * 2) stop streaming and dequeues any queued buffers, including those previously
> + * passed to the driver (after waiting for the driver to finish).
> + *
> + * This call can be used for pausing playback.
> + * The return values from this function are intended to be directly returned
> + * from vidioc_streamoff handler in the driver
> + */
> +int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
> +{
> + int ret = 0;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (type != q->type) {
> + dprintk(1, "streamoff: invalid stream type\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + if (!q->streaming) {
> + dprintk(1, "streamoff: not streaming\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + /*
> + * Cancel will pause streaming and remove all buffers from the driver
> + * and videobuf, effectively returning control over them to userspace.
> + */
> + __vb2_queue_cancel(q);
> +
> + dprintk(3, "Streamoff successful\n");
> +end:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_streamoff);
> +
> +/**
> + * __find_plane_by_off() - find plane associated with the given offset off
> + */
> +int __find_plane_by_off(struct vb2_queue *q, unsigned long off,
> + unsigned int *_buffer, unsigned int *_plane)
> +{
> + struct vb2_buffer *vb;
> + unsigned int buffer, plane;
> +
> + /*
> + * Go over all buffers and their planes, comparing the given offset
> + * with an offset assigned to each plane. If a match is found,
> + * return its buffer and plane numbers.
> + */
> + for (buffer = 0; buffer < q->num_buffers; ++buffer) {
> + vb = q->bufs[buffer];
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + if (vb->v4l2_planes[plane].m.mem_offset == off) {
> + *_buffer = buffer;
> + *_plane = plane;
> + return 0;
> + }
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +/**
> + * vb2_mmap() - map video buffers into application address space
> + * @q: videobuf2 queue
> + * @vma: vma passed to the mmap file operation handler in the driver
> + *
> + * Should be called from mmap file operation handler of a driver.
> + * This function maps one plane of one of the available video buffers to
> + * userspace. To map whole video memory allocated on reqbufs, this function
> + * has to be called once per each plane per each buffer previously allocated.
> + *
> + * When the userspace application calls mmap, it passes to it an offset returned
> + * to it earlier by the means of vidioc_querybuf handler. That offset acts as
> + * a "cookie", which is then used to identify the plane to be mapped.
> + * This function finds a plane with a matching offset and a mapping is performed
> + * by the means of a provided memory operation.
> + *
> + * The return values from this function are intended to be directly returned
> + * from the mmap handler in driver.
> + */
> +int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
> +{
> + unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
> + struct vb2_plane *vb_plane;
> + struct vb2_buffer *vb;
> + unsigned int buffer, plane;
> + int ret = -EINVAL;
> +
> + if (q->memory != V4L2_MEMORY_MMAP) {
> + dprintk(1, "Queue is not currently set up for mmap\n");
> + return ret;
> + }
> +
> + if (!(vma->vm_flags & VM_WRITE) || !(vma->vm_flags & VM_SHARED)) {
> + dprintk(1, "Invalid vma flags (need VM_WRITE | VM_SHARED)\n");
> + return ret;
> + }
> +
> + mutex_lock(&q->vb_lock);
> +
> + /*
> + * Find the plane corresponding to the offset passed by userspace.
> + */
> + ret = __find_plane_by_off(q, off, &buffer, &plane);
> + if (ret)
> + goto end;
> +
> + vb = q->bufs[buffer];
> + vb_plane = &vb->planes[plane];
> +
> + if (vb_plane->mapped) {
> + dprintk(1, "Plane already mapped\n");
> + goto end;
> + }
> +
> + if (!mem_ops(q, plane)->mmap) {
> + dprintk(1, "mmap not supported\n");
> + goto end;
> + }
> +
> + ret = mem_ops(q, plane)->mmap(vb_plane->mem_priv, vma);
> + if (ret)
> + goto end;
> +
> + vb_plane->mapped = 1;
> + vb->num_planes_mapped++;
> +
> + dprintk(3, "Buffer %d, plane %d successfully mapped\n", buffer, plane);
> +end:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_mmap);
> +
> +/**
> + * vb2_has_consumers() - return true if the userspace is waiting for a buffer
> + * @q: videobuf2 queue
> + *
> + * This function returns true if a userspace application is waiting for a buffer
> + * to be ready to dequeue (on which a hardware operation has been finished).
> + */
> +bool vb2_has_consumers(struct vb2_queue *q)
> +{
> + return waitqueue_active(&q->done_wq);
> +}
> +EXPORT_SYMBOL_GPL(vb2_has_consumers);
> +
> +/**
> + * vb2_poll() - implements poll userspace operation
> + * @q: videobuf2 queue
> + * @file: file argument passed to the poll file operation handler
> + * @wait: wait argument passed to the poll file operation handler
> + *
> + * This function implements poll file operation handler for a driver.
> + * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
> + * be informed that the file descriptor of a video device is available for
> + * reading.
> + * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
> + * will be reported as available for writing.
> + *
> + * The return values from this function are intended to be directly returned
> + * from poll handler in driver.
> + */
> +unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
> +{
> + unsigned long flags = 0;
> + unsigned int ret = 0;
> + struct vb2_buffer *vb = NULL;
> +
> + mutex_lock(&q->vb_lock);
> +
> + /*
> + * There is nothing to wait for if no buffers have already been queued.
> + */
> + if (list_empty(&q->queued_list)) {
> + ret = POLLERR;
> + goto end;
> + }
> +
> + poll_wait(file, &q->done_wq, wait);
> +
> + /*
> + * Take first buffer available for dequeuing.
> + */
> + spin_lock_irqsave(&q->done_lock, flags);
> + if (!list_empty(&q->done_list))
> + vb = list_first_entry(&q->done_list, struct vb2_buffer,
> + done_entry);
> + spin_unlock_irqrestore(&q->done_lock, flags);
> +
> + if (!vb)
> + goto end;
> +
> + if (vb->state == VB2_BUF_STATE_DONE
> + || vb->state == VB2_BUF_STATE_ERROR) {
> + if (V4L2_TYPE_IS_OUTPUT(q->type))
> + ret = POLLOUT | POLLWRNORM;
> + else
> + ret = POLLIN | POLLRDNORM;
> + }
> +end:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_poll);
Hmm... what about the read() method?
> +
> +/**
> + * vb2_queue_init() - initialize a videobuf2 queue
> + * @q: videobuf2 queue; this structure should be allocated in driver
> + * @ops: driver-specific callbacks
> + * @alloc_ctx: memory handler/allocator-specific context to be used;
> + * the given context will be used for memory allocation on all
> + * planes and buffers; it is possible to assign different contexts
> + * per plane, use vb2_set_alloc_ctx() for that
> + * @drv_lock: a lock for synchronization between the driver and videobuf,
> + * it should be locked by driver whenever an operation is being
> + * performed on a video buffer; this prevents videobuf from
> + * forcefully taking back a buffer from a driver in the middle
> + * of a hardware operation in case of an unexpected application
> + * close or queue cancellation
> + * @type: queue type
> + * @drv_priv: driver private data, may be NULL; it can be used by driver in
> + * driver-specific callbacks when issued
> + */
> +int vb2_queue_init(struct vb2_queue *q, const struct vb2_ops *ops,
> + const struct vb2_alloc_ctx *alloc_ctx,
> + spinlock_t *drv_lock, enum v4l2_buf_type type,
> + void *drv_priv)
> +{
> + unsigned int i;
> +
> + BUG_ON(!q);
> + BUG_ON(!ops);
> + BUG_ON(!ops->queue_negotiate);
> + BUG_ON(!ops->plane_setup);
> + BUG_ON(!ops->buf_queue);
> +
> + BUG_ON(!alloc_ctx);
> + BUG_ON(!alloc_ctx->mem_ops);
> +
> + memset(q, 0, sizeof *q);
> + q->ops = ops;
> +
> + for (i = 0; i < VIDEO_MAX_PLANES; ++i)
> + q->alloc_ctx[i] = alloc_ctx;
> +
> + q->drv_lock = drv_lock;
> + q->type = type;
> + q->drv_priv = drv_priv;
> +
> + mutex_init(&q->vb_lock);
> + INIT_LIST_HEAD(&q->queued_list);
> + INIT_LIST_HEAD(&q->done_list);
> + spin_lock_init(&q->done_lock);
> + init_waitqueue_head(&q->done_wq);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(vb2_queue_init);
> +
> +/**
> + * vb2_queue_release() - stop streaming, release the queue and free memory
> + * @q: videobuf2 queue
> + *
> + * This function stops streaming and performs necessary clean ups, including
> + * freeing video buffer memory. The driver is responsible for freeing
> + * the vb2_queue structure itself.
> + */
> +void vb2_queue_release(struct vb2_queue *q)
> +{
> + mutex_lock(&q->vb_lock);
> +
> + __vb2_queue_cancel(q);
> + __vb2_queue_free(q);
> +
> + mutex_unlock(&q->vb_lock);
> +}
> +EXPORT_SYMBOL_GPL(vb2_queue_release);
> +
> +MODULE_DESCRIPTION("Driver helper framework for Video for Linux 2");
> +MODULE_AUTHOR("Pawel Osciak");
> +MODULE_LICENSE("GPL");
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> new file mode 100644
> index 0000000..d51c973
> --- /dev/null
> +++ b/include/media/videobuf2-core.h
> @@ -0,0 +1,337 @@
> +/*
> + * videobuf2-core.h - V4L2 driver helper framework
> + *
> + * Copyright (C) 2010 Samsung Electronics
> + *
> + * Author: Pawel Osciak <p.osciak@samsung.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation.
> + */
> +#ifndef _MEDIA_VIDEOBUF2_CORE_H
> +#define _MEDIA_VIDEOBUF2_CORE_H
> +
> +#include <linux/mutex.h>
> +#include <linux/mm_types.h>
> +#include <linux/videodev2.h>
> +#include <linux/poll.h>
> +
> +/**
> + * enum vb2_buffer_state - current video buffer state
> + * @VB2_BUF_STATE_DEQUEUED: buffer under userspace control
> + * @VB2_BUF_STATE_QUEUED: buffer queued in videobuf, but not in driver
> + * @VB2_BUF_STATE_ACTIVE: buffer queued in driver and possibly used
> + * in a hardware operation
> + * @VB2_BUF_STATE_DONE: buffer returned from driver to videobuf, but
> + * not yet dequeued to userspace
> + * @VB2_BUF_STATE_ERROR: same as above, but the operation on the buffer
> + * has ended with an error, which will be reported
> + * to the userspace when it is dequeued
> + */
> +enum vb2_buffer_state {
> + VB2_BUF_STATE_DEQUEUED,
> + VB2_BUF_STATE_QUEUED,
> + VB2_BUF_STATE_ACTIVE,
> + VB2_BUF_STATE_DONE,
> + VB2_BUF_STATE_ERROR,
> +};
> +
> +/**
> + * struct vb2_plane - private videobuf per-plane info
> + * @mem_priv: allocator-specific, per-memory buffer private structure
> + * @mapped: set if the plane is mapped
> + */
> +struct vb2_plane {
> + void *mem_priv;
> + int mapped:1;
> +};
> +
> +/**
> + * struct vb2_buffer - represents a video buffer
> + * @v4l2_buf: struct v4l2_buffer associated with this buffer; can
> + * be read by the driver and relevant entries can be
> + * changed by the driver in case of CAPTURE types
> + * (such as timestamp)
> + * @v4l2_planes: struct v4l2_planes associated with this buffer; can
> + * be read by the driver and relevant entries can be
> + * changed by the driver in case of CAPTURE types
> + * (such as bytesused); NOTE that even for single-planar
> + * types, the v4l2_planes[0] struct should be used
> + * instead of v4l2_buf for filling bytesused - drivers
> + * should use the vb2_set_plane_payload() function for that
> + * @vb2_queue: the queue to which this driver belongs
> + * @drv_entry: list entry to be used by driver for storing the buffer
> + * @num_planes: number of planes in the buffer
> + * on an internal driver queue
> + * @state: current buffer state; do not change
> + * @queued_entry: entry on the queued buffers list, which holds all
> + * buffers queued from userspace
> + * @done_entry: entry on the list that stores all buffers ready to
> + * be dequeued to userspace
> + * @planes: private per-plane information; do not change
> + * @num_planes_mapped: number of mapped planes; do not change
> + */
> +struct vb2_buffer {
> + struct v4l2_buffer v4l2_buf;
> + struct v4l2_plane v4l2_planes[VIDEO_MAX_PLANES];
> +
> + struct vb2_queue *vb2_queue;
> +
> + struct list_head drv_entry;
> + unsigned int num_planes;
> +
> +/* Private: internal use only */
> + enum vb2_buffer_state state;
> +
> + struct list_head queued_entry;
> + struct list_head done_entry;
> +
> + struct vb2_plane planes[VIDEO_MAX_PLANES];
> + unsigned int num_planes_mapped;
> +};
> +
> +/**
> + * struct vb2_ops - driver-specific callbacks
> + * @queue_negotiate: called from a VIDIOC_REQBUFS handler, before
> + * memory allocation; driver should return the required
> + * number of buffers in num_buffers and the required number
> + * of planes per buffer in num_planes
> + * @plane_setup: called before memory allocation num_planes times;
> + * driver should return the required size of plane number
> + * plane_no
> + * @buf_queue: passes buffer vb to the driver; driver may use the
> + * vb->drv_entry member to store the buffer on its internal
> + * queue and start hardware operation on this buffer;
> + * @buf_init: called once after allocating a buffer (in MMAP case)
> + * or after acquiring a new USERPTR buffer; drivers may
> + * perform additional buffer-related initialization;
> + * initialization failure (return != 0) will prevent
> + * queue setup from completing successfully; optional
> + * @buf_prepare: called every time the buffer is queued from userspace;
> + * drivers may perform any initialization required before
> + * each hardware operation in this callback;
> + * if an error is returned, the buffer will not be queued
> + * in driver; optional
> + * @buf_finish: called before every dequeue of the buffer back to
> + * userspace; drivers may perform any operations required
> + * before userspace accesses the buffer; optional
> + * @buf_cleanup: called once before the buffer is freed; drivers may
> + * perform any additional cleanup; optional
> + */
> +struct vb2_ops {
> + int (*queue_negotiate)(struct vb2_queue *q, unsigned int *num_buffers,
> + unsigned int *num_planes);
> + int (*plane_setup)(struct vb2_queue *q,
> + unsigned int plane_no, unsigned long *plane_size);
> + void (*buf_queue)(struct vb2_buffer *vb);
> +
> + int (*buf_init)(struct vb2_buffer *vb);
> + int (*buf_prepare)(struct vb2_buffer *vb);
> + int (*buf_finish)(struct vb2_buffer *vb);
> + void (*buf_cleanup)(struct vb2_buffer *vb);
> +};
> +
> +/**
> + * struct vb2_queue - a videobuf queue
> + *
> + * @type: current queue type
> + * @memory: current memory type used
> + * @drv_priv: driver private data, passed on vb2_queue_init
> + * @bufs: videobuf buffer structures
> + * @num_buffers: number of allocated/used buffers
> + * @vb_lock: for ioctl handler and queue state changes synchronization
> + * @queued_list: list of buffers currently queued from userspace
> + * @done_list: list of buffers ready to be dequeued to userspace
> + * @done_lock: lock to protect done_list list
> + * @done_wq: waitqueue for processes waiting for buffers ready to be dequeued
> + * @drv_lock: driver lock for synchronization between driver and videobuf,
> + * passed on vb2_queue_init
> + * @ops: driver-specific callbacks
> + * @alloc_ctx: memory type/allocator-specific callbacks
> + * @streaming: current streaming state
> + * @userptr_supported: true if queue supports USERPTR types
> + * @mmap_supported: true if queue supports MMAP types
> + */
> +struct vb2_queue {
> + enum v4l2_buf_type type;
> + enum v4l2_memory memory;
> + void *drv_priv;
> +
> +/* private: internal use only */
> + struct vb2_buffer *bufs[VIDEO_MAX_FRAME];
> + unsigned int num_buffers;
> +
> + struct mutex vb_lock;
> + struct list_head queued_list;
> +
> + struct list_head done_list;
> + spinlock_t done_lock;
> + wait_queue_head_t done_wq;
> +
> + spinlock_t *drv_lock;
> +
> + const struct vb2_ops *ops;
> + const struct vb2_alloc_ctx *alloc_ctx[VIDEO_MAX_PLANES];
> +
> + int streaming:1;
> + int userptr_supported:1;
> + int mmap_supported:1;
> +};
> +
> +/* The below functions are documented in videobuf2-core.c */
> +void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
> +unsigned long vb2_plane_paddr(struct vb2_buffer *vb, unsigned int plane_no);
> +void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
> +bool vb2_has_consumers(struct vb2_queue *q);
> +
> +int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
> +int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
> +
> +int vb2_queue_init(struct vb2_queue *q, const struct vb2_ops *ops,
> + const struct vb2_alloc_ctx *alloc_ctx,
> + spinlock_t *drv_lock, enum v4l2_buf_type type,
> + void *drv_priv);
> +void vb2_queue_release(struct vb2_queue *q);
> +
> +int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
> +int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
> +
> +int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
> +int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
> +
> +int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
> +unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
> +
> +/**
> + * vb2_get_drv_priv() - return driver private data associated with the queue
> + * @q: videobuf queue
> + */
> +static inline void *vb2_get_drv_priv(struct vb2_queue *q)
> +{
> + return q->drv_priv;
> +}
> +
> +/**
> + * vb2_set_plane_payload() - set bytesused for the plane plane_no
> + * @vb: buffer for which plane payload should be set
> + * @plane_no: plane number for which payload should be set
> + * @size: payload in bytes
> + */
> +static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
> + unsigned int plane_no, unsigned long size)
> +{
> + if (!V4L2_TYPE_IS_MULTIPLANAR(vb->vb2_queue->type) && plane_no == 0)
> + vb->v4l2_buf.bytesused = size;
> + else
> + vb->v4l2_planes[plane_no].bytesused = size;
> +}
> +
> +/**
> + * vb2_plane_size() - return plane size in bytes
> + * @vb: buffer for which plane size should be returned
> + * @plane_no: plane number for which size should be returned
> + */
> +static inline unsigned long
> +vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
> +{
> + if (plane_no < vb->num_planes)
> + return vb->v4l2_planes[plane_no].length;
> + else
> + return 0;
> +}
> +
> +/**
> + * vb2_set_alloc_ctx() - use to assign a allocator context for a plane
> + * @q: videobuf queue
> + * @alloc_ctx: allocator context to be assigned
> + * @plane_no: plane number to which the context is to be assigned
> + *
> + * This function can be used to assign additional allocator contexts
> + * on a per-plane basis, if a driver requires such feature.
> + * When a driver passes an allocator context to the vb2_queue_init call,
> + * it is initially assigned to all planes. Driver can then use this call
> + * to selectively assign additional contexts to particular planes.
> + * A context assigned to plane_no will be used for memory operations
> + * on plane number plane_no for all buffers.
> + */
> +static inline void
> +vb2_set_alloc_ctx(struct vb2_queue *q, struct vb2_alloc_ctx *alloc_ctx,
> + unsigned int plane_no)
> +{
> + if (plane_no < VIDEO_MAX_PLANES)
> + q->alloc_ctx[plane_no] = alloc_ctx;
> +}
> +struct vb2_mem_ops;
> +
> +/**
> + * struct vb2_alloc_ctx - allocator/memory handler-specific context
> + * @mem_ops: memory operations used by the current context
> + *
> + * This structure is passed to the alloc() call and can be used to store
> + * additional allocator private data. In such case it can be embedded in
> + * a allocator private structure as its first member.
> + * In more complicated cases, separate contexts can be assigned to each plane,
> + * if required. This would allow separate memory allocation/handling strategies
> + * for each plane, which is useful for drivers requiring different memory types
> + * and/or handling for each plane.
> + *
> + * See videobuf2-vmalloc.c and videobuf2-dma-coherent.c for example usage.
> + */
> +struct vb2_alloc_ctx {
> + const struct vb2_mem_ops *mem_ops;
> +};
> +
> +/**
> + * struct vb2_mem_ops - memory handling/memory allocator operations
> + * @alloc: allocate video memory and, optionally, allocator private data,
> + * return NULL on failure or a pointer to allocator private,
> + * per-buffer data on success, NULL on failure; the returned
> + * private structure will then be passed as buf_priv argument
> + * to other ops in this structure
> + * @put: inform the allocator that the buffer will no longer be used;
> + * usually will result in the allocator freeing the buffer (if
> + * no other users of this buffer are present); the buf_priv
> + * argument is the allocator private per-buffer structure
> + * previously returned from the alloc callback
> + * @get_userptr: acquire userspace memory for a hardware operation; used for
> + * USERPTR memory types; vaddr is the address passed to the
> + * videobuf layer when queuing a video buffer of USERPTR type;
> + * should return an allocator private per-buffer structure
> + * associated with the buffer on success, NULL on failure;
> + * the returned private structure will then be passed as buf_priv
> + * argument to other ops in this structure
> + * @put_userptr: inform the allocator that a USERPTR buffer will no longer
> + * be used
> + * @vaddr: return a kernel virtual address to a given memory buffer
> + * associated with the passed private structure or NULL if no
> + * such mapping exists
> + * @paddr: return a physical address to a given memory buffer associated
> + * with the passed private structure or NULL if not available
> + * @num_users: return the current number of users of a memory buffer;
> + * return 1 if the videobuf layer (or actually the driver using
> + * it) is the only user
> + * @mmap: setup a userspace mapping for a given memory buffer under
> + * the provided virtual memory region
> + *
> + * Required ops for USERPTR types: get_userptr, put_userptr.
> + * Required ops for MMAP types: alloc, put, num_users, mmap.
> + */
> +struct vb2_mem_ops {
> + void *(*alloc)(const struct vb2_alloc_ctx *alloc_ctx,
> + unsigned long size);
> + void (*put)(void *buf_priv);
> +
> + void *(*get_userptr)(unsigned long vaddr,
> + unsigned long size);
> + void (*put_userptr)(void *buf_priv);
> +
> + void *(*vaddr)(void *buf_priv);
> + unsigned long (*paddr)(void *buf_priv);
> + unsigned int (*num_users)(void *buf_priv);
> +
> + int (*mmap)(void *buf_priv, struct vm_area_struct *vma);
> +};
> +
> +
> +#endif /* _MEDIA_VIDEOBUF2_CORE_H */
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Hello Mauro,
Thank you for the review. Please see my responses inline.
Please also note that my e-mail address has changed.
On 09/09/2010 07:29 PM, Mauro Carvalho Chehab wrote:
> Em 09-09-2010 06:19, Pawel Osciak escreveu:
>> Videobuf2 is a Video for Linux 2 API-compatible driver framework for
>> multimedia devices. It acts as an intermediate layer between userspace
>> applications and device drivers. It also provides low-level, modular
>> memory management functions for drivers.
>>
>> Videobuf2 eases driver development, reduces drivers' code size and
aids in
>> proper and consistent implementation of V4L2 API in drivers.
>>
>> Videobuf2 memory management backend is fully modular. This allows custom
>> memory management routines for devices and platforms with non-standard
>> memory management requirements to be plugged in, without changing the
>> high-level buffer management functions and API.
>>
>> The framework provides:
>> - implementations of streaming I/O V4L2 ioctls and file operations
>> - high-level video buffer, video queue and state management functions
>> - video buffer memory allocation and management
>>
>> Signed-off-by: Pawel Osciak<p.osciak@samsung.com>
>> Signed-off-by: Kyungmin Park<kyungmin.park@samsung.com>
>> ---
>> drivers/media/video/Kconfig | 3 +
>> drivers/media/video/Makefile | 2 +
>> drivers/media/video/videobuf2-core.c | 1457++++++++++++++++++++++++++++++++++
>> include/media/videobuf2-core.h | 337 ++++++++
>> 4 files changed, 1799 insertions(+), 0 deletions(-)
>> create mode 100644 drivers/media/video/videobuf2-core.c
>> create mode 100644 include/media/videobuf2-core.h
>>
(snip)
>> +/**
>> + * __vb2_wait_for_done_vb() - wait for a buffer to become available
>> + * for dequeuing
>> + *
>> + * Will sleep if required for nonblocking == false.
>> + */
>> +static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
>> +{
>> + int retval = 0;
>> +
>> +checks:
>> + if (!q->streaming) {
>> + dprintk(1, "Streaming off, will not wait for buffers\n");
>> + retval = -EINVAL;
>> + goto end;
>> + }
>> +
>> + /*
>> + * Buffers may be added to vb_done_list without holding the vb_lock,
>> + * but removal is performed only while holding both vb_lock and the
>> + * vb_done_lock spinlock. Thus we can be sure that as long as we hold
>> + * vb_lock, the list will remain not empty if this check succeeds.
>> + */
>> + if (list_empty(&q->done_list)) {
>> + if (nonblocking) {
>> + dprintk(1, "Nonblocking and no buffers to dequeue, "
>> + "will not wait\n");
>> + retval = -EAGAIN;
>> + goto end;
>> + }
>> +
>> + /*
>> + * We are streaming and nonblocking, wait for another buffer to
>> + * become ready or for streamoff. vb_lock is released to allow
>> + * streamoff or qbuf to be called while waiting.
>> + */
>> + mutex_unlock(&q->vb_lock);
>
> There's no mutex_lock before this call inside this function... It doesn't
> seem to be a good idea to call it with a mutex locked, and having aunlock/lock
> inside the fuction. The better would be to call it with mutexunlocked and let it
> lock/unlock where needed.
>
Hm, this might be tricky... I am pretty sure we have to hold the vb_lock for the
duration of dqbuf, so I cannot call it without holding the vb_lock. Would you
prefer to put that whole code into dqbuf? Sorry, I am not sure I understood you
correctly here...
>> + /*
>> + * Although the mutex is released here, we will be reevaluating
>> + * both conditions again after reacquiring it.
>> + */
>> + dprintk(3, "Will sleep waiting for buffers\n");
>> + retval = wait_event_interruptible(q->done_wq,
>> + !list_empty(&q->done_list) || !q->streaming);
>
> I think you could have a race condition here, as you're checking forlist_empty
> without a lock. The better approach would be to do something like:
>
> static int vb2_is_videobuf_empty(struct vb2_queue *q)
> {
> int is_empty;
>
> mutex_lock(&q->vb_lock);
>
> is_empty = list_empty(&q->done_list);
>
> mutex_unlock(&q->vb_lock);
>
> return is_empty;
> }
>
> static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
> {
> ...
> retval = wait_event_interruptible(q->done_wq,vb2_is_videobuf_empty(q) || !q->streaming);
> ...
> }
>
> This way, you'll always have the mutex locked when checking for listempty.
>
> Btw, shouldn't it be using, instead a spinlock?
>
There are two locks to be considered here:
- vb_lock - main mutex protecting most of the calls
- done_lock - a spinlock protecting done_list
Both vb_lock and done_lock have to be held to remove items from the
done_list, but only done_lock has to be held to add items to the
done_list.
After we check the done_list and find it non-empty, it will
stay that way as long as we hold vb_lock. It is possible that
new buffers will be added to it during that time, but this is not a
problem, since we will acquire the done_lock spinlock before removing
anything from the list.
I am indeed checking for list_empty without holding vb_lock, but this is
only a preliminary check. After wait_event_interruptible returns 0, I
jump back to checks:, acquire vb_lock and recheck for list_empty while
holding it. If the list is still non-empty by this second check, I
can return from the function still holding the vb_lock (so nothing can
be taken off the done_list in the meantime).
I am not sure if you solution would change things here... Since
vb2_is_videobuf_empty() you proposed releases vb_lock before returning
(and it is of course how it should be), we still have to jump back,
reacquire vb_lock and recheck. We cannot release vb_lock after verifying
that the list is nonempty until we remove the buffer from the done_list,
to make sure it stays nonempty.
Or maybe I am missing something here?
> To avoid needing to have a lock also for q->streaming, the betterwould be to define
> it as atomic_t.
>
Right, this is a good idea.
>> + mutex_lock(&q->vb_lock);
>> +
>> + if (retval)
>> + goto end;
>> +
>> + goto checks;
>> + }
>> +
>> +end:
>> + return retval;
>> +}
>> +
>> +/**
>> + * __vb2_get_done_vb() - get a buffer ready for dequeuing
>> + *
>> + * Will sleep if required for nonblocking == false.
>> + */
>> +static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer**vb,
>> + int nonblocking)
>> +{
>> + unsigned long flags;
>> + int ret = 0;
>> +
>> + /*
>> + * Wait for at least one buffer to become available on the done_list.
>> + */
>> + ret = __vb2_wait_for_done_vb(q, nonblocking);
>> + if (ret)
>> + goto end;
>> +
>> + /*
>> + * vb_lock has been held since we last verified that done_list is
>> + * not empty, so no need for another list_empty(done_list) check.
>> + */
>> + spin_lock_irqsave(&q->done_lock, flags);
>> + *vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
>> + list_del(&(*vb)->done_entry);
>> + spin_unlock_irqrestore(&q->done_lock, flags);
>> +
>> +end:
>> + return ret;
>> +}
>> +
>> +
>> +/**
>> + * vb2_dqbuf() - Dequeue a buffer to the userspace
>> + * @q: videobuf2 queue
>> + * @b: buffer structure passed from userspace to vidioc_dqbuf handler
>> + * in driver
>> + * @nonblocking: if true, this call will not sleep waiting for abuffer if no
>> + * buffers ready for dequeuing are present. Normally the driver
>> + * would be passing (file->f_flags& O_NONBLOCK) here
>> + *
>> + * Should be called from vidioc_dqbuf ioctl handler of a driver.
>> + * This function:
>> + * 1) verifies the passed buffer,
>> + * 2) calls buf_finish callback in the driver (if provided), in which
>> + * driver can perform any additional operations that may berequired before
>> + * returning the buffer to userspace, such as cache sync,
>> + * 3) the buffer struct members are filled with relevantinformation for
>> + * the userspace.
>> + *
>> + * The return values from this function are intended to be directlyreturned
>> + * from vidioc_dqbuf handler in driver.
>> + */
>> +int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, boolnonblocking)
>> +{
>> + struct vb2_buffer *vb = NULL;
>> + int ret;
>> +
>> + mutex_lock(&q->vb_lock);
>> +
>> + if (b->type != q->type) {
>> + dprintk(1, "dqbuf: invalid buffer type\n");
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> +
>> + ret = __vb2_get_done_vb(q,&vb, nonblocking);
>> + if (ret< 0) {
>> + dprintk(1, "dqbuf: error getting next done buffer\n");
>> + goto done;
>> + }
>> +
>> + if (q->ops->buf_finish) {
>> + ret = q->ops->buf_finish(vb);
>> + if (ret) {
>> + dprintk(1, "dqbuf: buffer finish failed\n");
>> + goto done;
>> + }
>> + }
>> +
>> + switch (vb->state) {
>> + case VB2_BUF_STATE_DONE:
>> + dprintk(3, "dqbuf: Returning done buffer\n");
>> + break;
>> + case VB2_BUF_STATE_ERROR:
>> + dprintk(3, "dqbuf: Returning done buffer with errors\n");
>> + break;
>> + default:
>> + dprintk(1, "dqbuf: Invalid buffer state\n");
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> +
>> + /* Fill buffer information for the userspace */
>> + __fill_v4l2_buffer(vb, b);
>> + /* Remove from videobuf queue */
>> + list_del(&vb->queued_entry);
>> +
>> + dprintk(1, "dqbuf of buffer %d, with state %d\n",
>> + vb->v4l2_buf.index, vb->state);
>> +
>> + vb->state = VB2_BUF_STATE_DEQUEUED;
>> +
>> +done:
>> + mutex_unlock(&q->vb_lock);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_dqbuf);
>> +
Hi Pawel,
I finally had some time for a code review:
On Thursday, September 09, 2010 11:19:42 Pawel Osciak wrote:
> Videobuf2 is a Video for Linux 2 API-compatible driver framework for
> multimedia devices. It acts as an intermediate layer between userspace
> applications and device drivers. It also provides low-level, modular
> memory management functions for drivers.
>
> Videobuf2 eases driver development, reduces drivers' code size and aids in
> proper and consistent implementation of V4L2 API in drivers.
>
> Videobuf2 memory management backend is fully modular. This allows custom
> memory management routines for devices and platforms with non-standard
> memory management requirements to be plugged in, without changing the
> high-level buffer management functions and API.
>
> The framework provides:
> - implementations of streaming I/O V4L2 ioctls and file operations
> - high-level video buffer, video queue and state management functions
> - video buffer memory allocation and management
>
> Signed-off-by: Pawel Osciak <p.osciak@samsung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> ---
> drivers/media/video/Kconfig | 3 +
> drivers/media/video/Makefile | 2 +
> drivers/media/video/videobuf2-core.c | 1457 ++++++++++++++++++++++++++++++++++
> include/media/videobuf2-core.h | 337 ++++++++
> 4 files changed, 1799 insertions(+), 0 deletions(-)
> create mode 100644 drivers/media/video/videobuf2-core.c
> create mode 100644 include/media/videobuf2-core.h
>
<snip>
> +/**
> + * vb2_reqbufs() - Initiate streaming
> + * @q: videobuf2 queue
> + * @req: struct passed from userspace to vidioc_reqbufs handler in driver
> + *
> + * Should be called from vidioc_reqbufs ioctl handler of a driver.
> + * This function:
> + * 1) verifies streaming parameters passed from the userspace,
> + * 2) sets up the queue,
> + * 3) negotiates number of buffers and planes per buffer with the driver
> + * to be used during streaming,
> + * 4) allocates internal buffer structures (struct vb2_buffer), according to
> + * the agreed parameters,
> + * 5) for MMAP memory type, allocates actual video memory, using the
> + * memory handling/allocation routines provided during queue initialization
> + *
> + * If req->count is 0, all the memory will be freed instead.
> + * If the queue has been allocated previously (by a previous vb2_reqbufs) call
> + * and the queue is not busy, memory will be reallocated.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_reqbufs handler in driver.
> + */
> +int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
> +{
> + unsigned int num_buffers, num_planes;
> + int ret = 0;
> +
> + if (req->memory != V4L2_MEMORY_MMAP
> + && req->memory != V4L2_MEMORY_USERPTR) {
> + dprintk(1, "reqbufs: unsupported memory type\n");
> + return -EINVAL;
> + }
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (req->type != q->type) {
> + dprintk(1, "reqbufs: queue type invalid\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + if (q->streaming) {
> + dprintk(1, "reqbufs: streaming active\n");
> + ret = -EBUSY;
> + goto end;
> + }
> +
> + if (req->count == 0) {
> + /* Free/release memory for count = 0, but only if unused */
> + if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) {
> + dprintk(1, "reqbufs: memory in use, cannot free\n");
> + ret = -EBUSY;
> + goto end;
> + }
> +
> + ret = __vb2_queue_free(q);
> + goto end;
> + }
> +
> + if (q->num_buffers != 0) {
> + /*
> + * We already have buffers allocated, so a reallocation is
> + * required, but only if the buffers are not in use.
> + */
> + if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) {
> + dprintk(1, "reqbufs: memory in use, "
> + "cannot reallocate\n");
> + ret = -EBUSY;
> + goto end;
> + }
> +
> + ret = __vb2_queue_free(q);
Hmmm, __vb2_queue_free can't fail: it always returns 0. If you make __vb2_queue_free
a void function, then there is no need to test for any error code.
> + if (ret)
> + goto end;
> + }
> +
> + num_buffers = min_t(unsigned int, req->count, VIDEO_MAX_FRAME);
> +
> + /* Ask the driver how many buffers and planes per buffer it requires */
> + ret = q->ops->queue_negotiate(q, &num_buffers, &num_planes);
> + if (ret)
> + goto end;
> +
> + /*
> + * Make sure all the required memory ops for given memory type
> + * are available.
> + */
> + if (req->memory == V4L2_MEMORY_MMAP
> + && __verify_mmap_ops(q, num_planes)) {
> + dprintk(1, "reqbufs: MMAP for current setup unsupported\n");
> + ret = -EINVAL;
> + goto end;
> + } else if (req->memory == V4L2_MEMORY_USERPTR
> + && __verify_userptr_ops(q, num_planes)) {
> + dprintk(1, "reqbufs: USERPTR for current setup unsupported\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + /* Finally, allocate buffers and video memory */
> + ret = __vb2_queue_alloc(q, req->memory, num_buffers, num_planes);
> + if (ret < 0) {
> + dprintk(1, "Memory allocation failed with error: %d\n", ret);
> + } else {
> + /*
> + * Return the number of successfully allocated buffers
> + * to the userspace.
> + */
> + req->count = ret;
> + ret = 0;
> + }
> +
> + q->memory = req->memory;
> +
> +end:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_reqbufs);
> +
> +/**
> + * vb2_plane_vaddr() - Return a kernel virtual address of a given plane
> + * @vb: vb2_buffer to which the plane in question belongs to
> + * @plane_no: plane number for which the address is to be returned
> + *
> + * This function returns a kernel virtual address of a given plane if
> + * such a mapping exist, NULL otherwise.
> + */
> +void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> +
> + if (plane_no > vb->num_planes)
> + return NULL;
> +
> + return call_memop(q, plane_no, vaddr, vb->planes[plane_no].mem_priv);
> +
> +}
> +EXPORT_SYMBOL_GPL(vb2_plane_vaddr);
> +
> +/**
> + * vb2_plane_paddr() - Return the physical address of a given plane
> + * @vb: vb2_buffer to which the plane in question belongs to
> + * @plane_no: plane number for which the address is to be returned
> + *
> + * This function returns a physical address of a given plane if available,
> + * NULL otherwise.
> + */
> +unsigned long vb2_plane_paddr(struct vb2_buffer *vb, unsigned int plane_no)
Shouldn't this return phys_addr_t? That seems more appropriate.
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> +
> + if (plane_no > vb->num_planes)
> + return 0UL;
> +
> + return call_memop(q, plane_no, paddr, vb->planes[plane_no].mem_priv);
> +}
> +EXPORT_SYMBOL_GPL(vb2_plane_paddr);
> +
> +/**
> + * vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
> + * @vb: vb2_buffer returned from the driver
> + * @state: either VB2_BUF_STATE_DONE if the operation finished successfully
> + * or VB2_BUF_STATE_ERROR if the operation finished with an error
> + *
> + * This function should be called by the driver after a hardware operation on
> + * a buffer is finished and the buffer may be returned to userspace. The driver
> + * cannot use this buffer anymore until it is queued back to it by videobuf
> + * by the means of buf_queue callback. Only buffers previously queued to the
> + * driver by buf_queue can be passed to this function.
> + */
> +void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + unsigned long flags;
> +
> + if (vb->state != VB2_BUF_STATE_ACTIVE)
> + return;
> +
> + if (state != VB2_BUF_STATE_DONE && state != VB2_BUF_STATE_ERROR)
> + return;
These two checks should call WARN() to clearly signal a driver bug.
> +
> + dprintk(4, "Done processing on buffer %d, state: %d\n",
> + vb->v4l2_buf.index, vb->state);
> +
> + /* Add the buffer to the done buffers list */
> + spin_lock_irqsave(&q->done_lock, flags);
> + vb->state = state;
> + list_add_tail(&vb->done_entry, &q->done_list);
> + spin_unlock_irqrestore(&q->done_lock, flags);
> +
> + /* Inform any processes that may be waiting for buffers */
> + wake_up_interruptible(&q->done_wq);
> +}
> +EXPORT_SYMBOL_GPL(vb2_buffer_done);
> +
> +/**
> + * __fill_vb2_buffer() - fill a vb2_buffer with information provided in
> + * a v4l2_buffer by the userspace
> + */
> +static int __fill_vb2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b,
> + struct v4l2_plane *v4l2_planes)
> +{
> + unsigned int plane;
> + int ret;
> +
> + if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
> + /*
> + * Verify that the userspace gave us a valid array for
> + * plane information.
> + */
> + ret = __verify_planes_array(vb, b);
> + if (ret)
> + return ret;
> +
> + /* Fill in driver-provided information for OUTPUT types */
> + if (V4L2_TYPE_IS_OUTPUT(b->type)) {
> + /*
> + * Will have to go up to b->length when API starts
> + * accepting variable number of planes.
> + */
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + v4l2_planes[plane].bytesused =
> + b->m.planes[plane].bytesused;
> + v4l2_planes[plane].data_offset =
> + b->m.planes[plane].data_offset;
> + }
> + }
> +
> + if (b->memory == V4L2_MEMORY_USERPTR) {
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + v4l2_planes[plane].m.userptr =
> + b->m.planes[plane].m.userptr;
> + v4l2_planes[plane].length =
> + b->m.planes[plane].length;
> + }
> + }
> + } else {
> + /*
> + * Single-planar buffers do not use planes array,
> + * so fill in relevant v4l2_buffer struct fields instead.
> + * In videobuf we use our internal V4l2_planes struct for
> + * single-planar buffers as well, for simplicity.
> + */
> + if (V4L2_TYPE_IS_OUTPUT(b->type))
> + v4l2_planes[0].bytesused = b->bytesused;
> +
> + if (b->memory == V4L2_MEMORY_USERPTR) {
> + v4l2_planes[0].m.userptr = b->m.userptr;
> + v4l2_planes[0].length = b->length;
> + }
> + }
> +
> + vb->v4l2_buf.field = b->field;
> + vb->v4l2_buf.timestamp = b->timestamp;
> +
> + return 0;
> +}
> +
> +/**
> + * __qbuf_userptr() - handle qbuf of a USERPTR buffer
> + */
> +static int __qbuf_userptr(struct vb2_buffer *vb, struct v4l2_buffer *b)
> +{
> + struct v4l2_plane planes[VIDEO_MAX_PLANES];
> + struct vb2_queue *q = vb->vb2_queue;
> + void *mem_priv = NULL;
> + unsigned int plane;
> + int ret;
> +
> + /* Verify and copy relevant information provided by the userspace */
> + ret = __fill_vb2_buffer(vb, b, planes);
> + if (ret)
> + return ret;
> +
> + for (plane = 0; plane < vb->num_planes; ++plane) {
> + /* Skip the plane if already verified */
> + if (vb->v4l2_planes[plane].m.userptr == planes[plane].m.userptr
> + && vb->v4l2_planes[plane].length == planes[plane].length)
> + continue;
> +
> + dprintk(3, "qbuf: userspace address for plane %d changed, "
> + "reacquiring memory\n", plane);
> +
> + /* Release previously acquired memory if present */
> + if (vb->planes[plane].mem_priv)
> + call_memop(q, plane, put_userptr,
> + vb->planes[plane].mem_priv);
> +
> + vb->planes[plane].mem_priv = NULL;
> +
> + /* Acquire each plane's memory */
> + if (mem_ops(q, plane)->get_userptr) {
> + mem_priv = mem_ops(q, plane)->get_userptr(
> + planes[plane].m.userptr,
> + planes[plane].length);
> + if (IS_ERR(mem_priv)) {
> + dprintk(1, "qbuf: failed acquiring userspace "
> + "memory for plane %d\n", plane);
> + goto err;
> + }
Just to verify my understanding: get_userptr is responsible for locking the
pages into memory and to increase a use count on that memory. So if the app
would do a QBUF, then free the memory and allocate a new buffer, then the
original buffer memory is not released until put_userptr is called, and the
pointer of the new buffer that the app allocated will always be different from
the original buffer (since it was still in use when the app allocated the new
one).
I've always wondered if something nasty like this was handled correctly. I never
had the time to dive into the mm core, though.
> +
> + vb->planes[plane].mem_priv = mem_priv;
> + }
> + }
> +
> + /*
> + * Call driver-specific initialization on the newly acquired buffer,
> + * if provided.
> + */
> + if (q->ops->buf_init) {
> + ret = q->ops->buf_init(vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer initialization failed\n");
> + goto err;
> + }
> + }
> +
> + /*
> + * Now that everything is in order, copy relevant information
> + * provided by userspace.
> + */
> + for (plane = 0; plane < vb->num_planes; ++plane)
> + vb->v4l2_planes[plane] = planes[plane];
> +
> + return 0;
> +err:
> + /* In case of errors, release planes that were already acquired */
> + for (; plane > 0; --plane) {
> + call_memop(q, plane, put_userptr,
> + vb->planes[plane - 1].mem_priv);
> + vb->planes[plane - 1].mem_priv = NULL;
> + }
> +
> + return ret;
> +}
> +
> +/**
> + * __qbuf_mmap() - handle qbuf of an MMAP buffer
> + */
> +static int __qbuf_mmap(struct vb2_buffer *vb, struct v4l2_buffer *b)
> +{
> + return __fill_vb2_buffer(vb, b, vb->v4l2_planes);
> +}
> +
> +/**
> + * __enqueue_in_driver() - enqueue a vb2_buffer in driver for processing
> + */
> +static void __enqueue_in_driver(struct vb2_buffer *vb)
> +{
> + struct vb2_queue *q = vb->vb2_queue;
> + unsigned long flags;
> +
> + spin_lock_irqsave(q->drv_lock, flags);
> + vb->state = VB2_BUF_STATE_ACTIVE;
> + q->ops->buf_queue(vb);
> + spin_unlock_irqrestore(q->drv_lock, flags);
> +}
> +
> +/**
> + * vb2_qbuf() - Queue a buffer from userspace
> + * @q: videobuf2 queue
> + * @b: buffer structure passed from userspace to vidioc_qbuf handler
> + * in driver
> + *
> + * Should be called from vidioc_qbuf ioctl handler of a driver.
> + * This function:
> + * 1) verifies the passed buffer,
> + * 2) calls buf_prepare callback in the driver (if provided), in which
> + * driver-specific buffer initialization can be performed,
> + * 3) if streaming is on, queues the buffer in driver by the means of buf_queue
> + * callback for processing.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_qbuf handler in driver.
> + */
> +int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
> +{
> + struct vb2_buffer *vb;
> + int ret;
> +
> + mutex_lock(&q->vb_lock);
> +
> + ret = -EINVAL;
> + if (b->type != q->type) {
> + dprintk(1, "qbuf: invalid buffer type\n");
> + goto done;
> + }
> + if (b->index >= q->num_buffers) {
> + dprintk(1, "qbuf: buffer index out of range\n");
> + goto done;
> + }
> +
> + vb = q->bufs[b->index];
> + if (NULL == vb) {
> + /* Should never happen */
> + dprintk(1, "qbuf: buffer is NULL\n");
> + goto done;
> + }
> +
> + if (b->memory != q->memory) {
> + dprintk(1, "qbuf: invalid memory type\n");
> + goto done;
> + }
> +
> + if (vb->state != VB2_BUF_STATE_DEQUEUED) {
> + dprintk(1, "qbuf: buffer already in use\n");
> + goto done;
> + }
> +
> + if (q->memory == V4L2_MEMORY_MMAP)
> + ret = __qbuf_mmap(vb, b);
> + else if (q->memory == V4L2_MEMORY_USERPTR)
> + ret = __qbuf_userptr(vb, b);
> + if (ret)
> + goto done;
> +
> + if (q->ops->buf_prepare) {
> + ret = q->ops->buf_prepare(vb);
> + if (ret) {
> + dprintk(1, "qbuf: buffer preparation failed\n");
> + goto done;
> + }
> + }
> +
> + /*
> + * Add to the queued buffers list, a buffer will stay on it until
> + * dequeued in dqbuf.
> + */
> + list_add_tail(&vb->queued_entry, &q->queued_list);
> + vb->state = VB2_BUF_STATE_QUEUED;
> +
> + /*
> + * If already streaming, give the buffer to driver for processing.
> + * If not, the buffer will be given to driver on next streamon.
> + */
> + if (q->streaming)
> + __enqueue_in_driver(vb);
> +
> + dprintk(1, "qbuf of buffer %d succeeded\n", vb->v4l2_buf.index);
> + ret = 0;
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_qbuf);
> +
> +/**
> + * __vb2_wait_for_done_vb() - wait for a buffer to become available
> + * for dequeuing
> + *
> + * Will sleep if required for nonblocking == false.
> + */
> +static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
> +{
> + int retval = 0;
> +
> +checks:
> + if (!q->streaming) {
> + dprintk(1, "Streaming off, will not wait for buffers\n");
> + retval = -EINVAL;
> + goto end;
> + }
> +
> + /*
> + * Buffers may be added to vb_done_list without holding the vb_lock,
> + * but removal is performed only while holding both vb_lock and the
> + * vb_done_lock spinlock. Thus we can be sure that as long as we hold
> + * vb_lock, the list will remain not empty if this check succeeds.
> + */
> + if (list_empty(&q->done_list)) {
> + if (nonblocking) {
> + dprintk(1, "Nonblocking and no buffers to dequeue, "
> + "will not wait\n");
> + retval = -EAGAIN;
> + goto end;
> + }
> +
> + /*
> + * We are streaming and nonblocking, wait for another buffer to
> + * become ready or for streamoff. vb_lock is released to allow
> + * streamoff or qbuf to be called while waiting.
> + */
> + mutex_unlock(&q->vb_lock);
> + /*
> + * Although the mutex is released here, we will be reevaluating
> + * both conditions again after reacquiring it.
> + */
> + dprintk(3, "Will sleep waiting for buffers\n");
> + retval = wait_event_interruptible(q->done_wq,
> + !list_empty(&q->done_list) || !q->streaming);
> + mutex_lock(&q->vb_lock);
> +
> + if (retval)
> + goto end;
> +
> + goto checks;
> + }
> +
> +end:
> + return retval;
> +}
> +
> +/**
> + * __vb2_get_done_vb() - get a buffer ready for dequeuing
> + *
> + * Will sleep if required for nonblocking == false.
> + */
> +static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer **vb,
> + int nonblocking)
> +{
> + unsigned long flags;
> + int ret = 0;
> +
> + /*
> + * Wait for at least one buffer to become available on the done_list.
> + */
> + ret = __vb2_wait_for_done_vb(q, nonblocking);
> + if (ret)
> + goto end;
> +
> + /*
> + * vb_lock has been held since we last verified that done_list is
> + * not empty, so no need for another list_empty(done_list) check.
> + */
> + spin_lock_irqsave(&q->done_lock, flags);
> + *vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
> + list_del(&(*vb)->done_entry);
> + spin_unlock_irqrestore(&q->done_lock, flags);
> +
> +end:
> + return ret;
> +}
> +
> +
> +/**
> + * vb2_dqbuf() - Dequeue a buffer to the userspace
> + * @q: videobuf2 queue
> + * @b: buffer structure passed from userspace to vidioc_dqbuf handler
> + * in driver
> + * @nonblocking: if true, this call will not sleep waiting for a buffer if no
> + * buffers ready for dequeuing are present. Normally the driver
> + * would be passing (file->f_flags & O_NONBLOCK) here
> + *
> + * Should be called from vidioc_dqbuf ioctl handler of a driver.
> + * This function:
> + * 1) verifies the passed buffer,
> + * 2) calls buf_finish callback in the driver (if provided), in which
> + * driver can perform any additional operations that may be required before
> + * returning the buffer to userspace, such as cache sync,
> + * 3) the buffer struct members are filled with relevant information for
> + * the userspace.
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_dqbuf handler in driver.
> + */
> +int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking)
> +{
> + struct vb2_buffer *vb = NULL;
> + int ret;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (b->type != q->type) {
> + dprintk(1, "dqbuf: invalid buffer type\n");
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + ret = __vb2_get_done_vb(q, &vb, nonblocking);
> + if (ret < 0) {
> + dprintk(1, "dqbuf: error getting next done buffer\n");
> + goto done;
> + }
> +
> + if (q->ops->buf_finish) {
> + ret = q->ops->buf_finish(vb);
> + if (ret) {
> + dprintk(1, "dqbuf: buffer finish failed\n");
> + goto done;
> + }
> + }
> +
> + switch (vb->state) {
> + case VB2_BUF_STATE_DONE:
> + dprintk(3, "dqbuf: Returning done buffer\n");
> + break;
> + case VB2_BUF_STATE_ERROR:
> + dprintk(3, "dqbuf: Returning done buffer with errors\n");
> + break;
> + default:
> + dprintk(1, "dqbuf: Invalid buffer state\n");
Isn't it a driver bug if we get here? In that case we need a WARN.
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + /* Fill buffer information for the userspace */
> + __fill_v4l2_buffer(vb, b);
> + /* Remove from videobuf queue */
> + list_del(&vb->queued_entry);
> +
> + dprintk(1, "dqbuf of buffer %d, with state %d\n",
> + vb->v4l2_buf.index, vb->state);
> +
> + vb->state = VB2_BUF_STATE_DEQUEUED;
> +
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_dqbuf);
> +
> +/**
> + * vb2_streamon - start streaming
> + * @q: videobuf2 queue
> + * @type: type argument passed from userspace to vidioc_streamon handler
> + *
> + * Should be called from vidioc_streamon handler of a driver.
> + * This function:
> + * 1) verifies current state
> + * 2) starts streaming and passes any previously queued buffers to the driver
> + *
> + * The return values from this function are intended to be directly returned
> + * from vidioc_streamon handler in the driver.
> + */
> +int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
> +{
> + struct vb2_buffer *vb;
> + int ret = 0;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (type != q->type) {
> + dprintk(1, "streamon: invalid stream type\n");
> + ret = -EINVAL;
> + goto done;
> + }
> +
> + if (q->streaming) {
> + dprintk(1, "streamon: already streaming\n");
> + ret = -EBUSY;
> + goto done;
> + }
> +
> + /*
> + * Cannot start streaming on an OUTPUT device if no buffers have
> + * been queued yet.
> + */
> + if (V4L2_TYPE_IS_OUTPUT(q->type)) {
> + if (list_empty(&q->queued_list)) {
> + dprintk(1, "streamon: no output buffers queued\n");
> + ret = -EINVAL;
> + goto done;
> + }
> + }
> +
> + q->streaming = 1;
> +
> + /*
> + * If any buffers were queued before streamon,
> + * we can now pass them to driver for processing.
> + */
> + list_for_each_entry(vb, &q->queued_list, queued_entry)
> + __enqueue_in_driver(vb);
> +
> + dprintk(3, "Streamon successful\n");
> +done:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_streamon);
> +
> +/**
> + * __vb2_queue_cancel() - cancel and stop (pause) streaming
> + *
> + * Removes all queued buffers from driver's queue and all buffers queued by
> + * userspace from videobuf's queue. Returns to state after reqbufs.
> + */
> +static void __vb2_queue_cancel(struct vb2_queue *q)
> +{
> + unsigned long flags = 0;
> + int i;
> +
> + q->streaming = 0;
> +
> + /*
> + * Remove buffers from driver's queue. If a hardware operation
> + * is currently underway, drv_lock should be claimed and we will
> + * have to wait for it to finish before taking back buffers.
> + */
> + spin_lock_irqsave(q->drv_lock, flags);
> + for (i = 0; i < q->num_buffers; ++i) {
> + if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
> + list_del(&q->bufs[i]->drv_entry);
> + q->bufs[i]->state = VB2_BUF_STATE_DEQUEUED;
> + }
> + spin_unlock_irqrestore(q->drv_lock, flags);
I feel that this spinlock is too simplistic. I think we need a new op:
stop_streaming() or something like that. The driver will stop any streaming
and dequeue any active buffers. And if necessary it has to wait for any DMA
in progress to finish first.
That will also make it possible to remove the drv_lock altogether and make the
driver responsible for proper locking in buf_queue and stop_streaming.
Actually, it might also be an idea to implement a start_streaming op for symmetry.
> +
> + /*
> + * Remove all buffers from videobuf's list...
> + */
> + INIT_LIST_HEAD(&q->queued_list);
> + /*
> + * ...and done list; userspace will not receive any buffers it
> + * has not already dequeued before initiating cancel.
> + */
> + INIT_LIST_HEAD(&q->done_list);
Is this correct? Shouldn't put_userptr be called for all queued and done buffers?
> + wake_up_interruptible_all(&q->done_wq);
> +}
> +
> +/**
> + * vb2_streamoff - stop streaming
> + * @q: videobuf2 queue
> + * @type: type argument passed from userspace to vidioc_streamoff handler
> + *
> + * Should be called from vidioc_streamoff handler of a driver.
> + * This function:
> + * 1) verifies current state,
> + * 2) stop streaming and dequeues any queued buffers, including those previously
> + * passed to the driver (after waiting for the driver to finish).
> + *
> + * This call can be used for pausing playback.
> + * The return values from this function are intended to be directly returned
> + * from vidioc_streamoff handler in the driver
> + */
> +int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
> +{
> + int ret = 0;
> +
> + mutex_lock(&q->vb_lock);
> +
> + if (type != q->type) {
> + dprintk(1, "streamoff: invalid stream type\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + if (!q->streaming) {
> + dprintk(1, "streamoff: not streaming\n");
> + ret = -EINVAL;
> + goto end;
> + }
> +
> + /*
> + * Cancel will pause streaming and remove all buffers from the driver
> + * and videobuf, effectively returning control over them to userspace.
> + */
> + __vb2_queue_cancel(q);
> +
> + dprintk(3, "Streamoff successful\n");
> +end:
> + mutex_unlock(&q->vb_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(vb2_streamoff);
<snip>
Some general remarks:
1) It is probably useful to add a simply inline function like this:
static inline bool vb2_is_streaming(struct vb2_queue *q)
{
return q->streaming;
}
2) We need very clear documentation detailing:
- where the struct vb2_queue has to be stored (it should be associated with the
video_device struct or the v4l2_device struct if there is only one queue).
- when to call vb2_queue_init (before registering the device node, I think).
- when to call vb2_queue_release (after unregistering the device node? Does that
also work well with USB devices after a disconnect? I think it is OK, but I'm
not 100% certain.)
- how does it work if multiple file handles are open? If fh A calls REQBUFS, is fh
B allowed to call it again? My feeling is that once a fh calls REQBUFS, the
queue is associated with that fh until REQBUFS with count == 0 is called, or
until the fh is closed. All the other streaming ioctls should be called from
that fh. To implement this reqbufs should be passed a struct file (or a v4l2_fh?).
And for the others we either need this as well or we add a simple inline function
checking this that drivers can call.
3) Read/write will have its own issues: if the driver supports read/write, then
some internal checks are needed: once reqbufs was called on a fh, read/write
should not be allowed (until REQBUFS(0), that is). The same is true vice versa,
except that once you've started reading or writing the only way to go back to
streaming I/O is by closing the fh first.
4) If poll is called without a preceding reqbufs or read, then it should initiate
streaming and mark the queue as being in read (or write) mode. It's the way poll
is supposed to work for read or write.
5) Allowing mixing of read/write and streaming I/O. I am very much opposed to this.
First of all it will cause skipped frames since read will steal from dqbuf (or
vice versa, depending on how you look at it). Once you start to read it will also
be impossible to use REQBUFS(0), and the internal administration will be a nightmare.
Frankly, I don't think there is a way to implement this in a way that makes sense.
We should probably investigate those utilities that are supposed to do this.
I understand that they are xawtv and xdtv.
Regards,
Hans
Hi Hans,
Big thanks for the review!
On 09/25/2010 07:27 AM, Hans Verkuil wrote:
> Hi Pawel,
>
> I finally had some time for a code review:
>
> On Thursday, September 09, 2010 11:19:42 Pawel Osciak wrote:
>> Videobuf2 is a Video for Linux 2 API-compatible driver framework for
>> multimedia devices. It acts as an intermediate layer between userspace
>> applications and device drivers. It also provides low-level, modular
>> memory management functions for drivers.
>>
>> Videobuf2 eases driver development, reduces drivers' code size and aids in
>> proper and consistent implementation of V4L2 API in drivers.
>>
>> Videobuf2 memory management backend is fully modular. This allows custom
>> memory management routines for devices and platforms with non-standard
>> memory management requirements to be plugged in, without changing the
>> high-level buffer management functions and API.
>>
>> The framework provides:
>> - implementations of streaming I/O V4L2 ioctls and file operations
>> - high-level video buffer, video queue and state management functions
>> - video buffer memory allocation and management
>>
>> Signed-off-by: Pawel Osciak<p.osciak@samsung.com>
>> Signed-off-by: Kyungmin Park<kyungmin.park@samsung.com>
>> ---
>> drivers/media/video/Kconfig | 3 +
>> drivers/media/video/Makefile | 2 +
>> drivers/media/video/videobuf2-core.c | 1457 ++++++++++++++++++++++++++++++++++
>> include/media/videobuf2-core.h | 337 ++++++++
>> 4 files changed, 1799 insertions(+), 0 deletions(-)
>> create mode 100644 drivers/media/video/videobuf2-core.c
>> create mode 100644 include/media/videobuf2-core.h
>>
>
> <snip>
>
<snip>
>> +
>> + dprintk(4, "Done processing on buffer %d, state: %d\n",
>> + vb->v4l2_buf.index, vb->state);
>> +
>> + /* Add the buffer to the done buffers list */
>> + spin_lock_irqsave(&q->done_lock, flags);
>> + vb->state = state;
>> + list_add_tail(&vb->done_entry,&q->done_list);
>> + spin_unlock_irqrestore(&q->done_lock, flags);
>> +
>> + /* Inform any processes that may be waiting for buffers */
>> + wake_up_interruptible(&q->done_wq);
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_buffer_done);
>> +
>> +/**
>> + * __fill_vb2_buffer() - fill a vb2_buffer with information provided in
>> + * a v4l2_buffer by the userspace
>> + */
>> +static int __fill_vb2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b,
>> + struct v4l2_plane *v4l2_planes)
>> +{
>> + unsigned int plane;
>> + int ret;
>> +
>> + if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
>> + /*
>> + * Verify that the userspace gave us a valid array for
>> + * plane information.
>> + */
>> + ret = __verify_planes_array(vb, b);
>> + if (ret)
>> + return ret;
>> +
>> + /* Fill in driver-provided information for OUTPUT types */
>> + if (V4L2_TYPE_IS_OUTPUT(b->type)) {
>> + /*
>> + * Will have to go up to b->length when API starts
>> + * accepting variable number of planes.
>> + */
>> + for (plane = 0; plane< vb->num_planes; ++plane) {
>> + v4l2_planes[plane].bytesused =
>> + b->m.planes[plane].bytesused;
>> + v4l2_planes[plane].data_offset =
>> + b->m.planes[plane].data_offset;
>> + }
>> + }
>> +
>> + if (b->memory == V4L2_MEMORY_USERPTR) {
>> + for (plane = 0; plane< vb->num_planes; ++plane) {
>> + v4l2_planes[plane].m.userptr =
>> + b->m.planes[plane].m.userptr;
>> + v4l2_planes[plane].length =
>> + b->m.planes[plane].length;
>> + }
>> + }
>> + } else {
>> + /*
>> + * Single-planar buffers do not use planes array,
>> + * so fill in relevant v4l2_buffer struct fields instead.
>> + * In videobuf we use our internal V4l2_planes struct for
>> + * single-planar buffers as well, for simplicity.
>> + */
>> + if (V4L2_TYPE_IS_OUTPUT(b->type))
>> + v4l2_planes[0].bytesused = b->bytesused;
>> +
>> + if (b->memory == V4L2_MEMORY_USERPTR) {
>> + v4l2_planes[0].m.userptr = b->m.userptr;
>> + v4l2_planes[0].length = b->length;
>> + }
>> + }
>> +
>> + vb->v4l2_buf.field = b->field;
>> + vb->v4l2_buf.timestamp = b->timestamp;
>> +
>> + return 0;
>> +}
>> +
>> +/**
>> + * __qbuf_userptr() - handle qbuf of a USERPTR buffer
>> + */
>> +static int __qbuf_userptr(struct vb2_buffer *vb, struct v4l2_buffer *b)
>> +{
>> + struct v4l2_plane planes[VIDEO_MAX_PLANES];
>> + struct vb2_queue *q = vb->vb2_queue;
>> + void *mem_priv = NULL;
>> + unsigned int plane;
>> + int ret;
>> +
>> + /* Verify and copy relevant information provided by the userspace */
>> + ret = __fill_vb2_buffer(vb, b, planes);
>> + if (ret)
>> + return ret;
>> +
>> + for (plane = 0; plane< vb->num_planes; ++plane) {
>> + /* Skip the plane if already verified */
>> + if (vb->v4l2_planes[plane].m.userptr == planes[plane].m.userptr
>> + && vb->v4l2_planes[plane].length == planes[plane].length)
>> + continue;
>> +
>> + dprintk(3, "qbuf: userspace address for plane %d changed, "
>> + "reacquiring memory\n", plane);
>> +
>> + /* Release previously acquired memory if present */
>> + if (vb->planes[plane].mem_priv)
>> + call_memop(q, plane, put_userptr,
>> + vb->planes[plane].mem_priv);
>> +
>> + vb->planes[plane].mem_priv = NULL;
>> +
>> + /* Acquire each plane's memory */
>> + if (mem_ops(q, plane)->get_userptr) {
>> + mem_priv = mem_ops(q, plane)->get_userptr(
>> + planes[plane].m.userptr,
>> + planes[plane].length);
>> + if (IS_ERR(mem_priv)) {
>> + dprintk(1, "qbuf: failed acquiring userspace "
>> + "memory for plane %d\n", plane);
>> + goto err;
>> + }
>
> Just to verify my understanding: get_userptr is responsible for locking the
> pages into memory and to increase a use count on that memory. So if the app
> would do a QBUF, then free the memory and allocate a new buffer, then the
> original buffer memory is not released until put_userptr is called, and the
> pointer of the new buffer that the app allocated will always be different from
> the original buffer (since it was still in use when the app allocated the new
> one).
>
Yes. If an application frees a buffer, the use count is still >0, since the driver
is still holding it. When the application queues the new buffer, userptr code
sees that the pointer has changed, releases the old memory and get()s the new one.
> I've always wondered if something nasty like this was handled correctly. I never
> had the time to dive into the mm core, though.
>
<snip>
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> +
>> + /* Fill buffer information for the userspace */
>> + __fill_v4l2_buffer(vb, b);
>> + /* Remove from videobuf queue */
>> + list_del(&vb->queued_entry);
>> +
>> + dprintk(1, "dqbuf of buffer %d, with state %d\n",
>> + vb->v4l2_buf.index, vb->state);
>> +
>> + vb->state = VB2_BUF_STATE_DEQUEUED;
>> +
>> +done:
>> + mutex_unlock(&q->vb_lock);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_dqbuf);
>> +
>> +/**
>> + * vb2_streamon - start streaming
>> + * @q: videobuf2 queue
>> + * @type: type argument passed from userspace to vidioc_streamon handler
>> + *
>> + * Should be called from vidioc_streamon handler of a driver.
>> + * This function:
>> + * 1) verifies current state
>> + * 2) starts streaming and passes any previously queued buffers to the driver
>> + *
>> + * The return values from this function are intended to be directly returned
>> + * from vidioc_streamon handler in the driver.
>> + */
>> +int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
>> +{
>> + struct vb2_buffer *vb;
>> + int ret = 0;
>> +
>> + mutex_lock(&q->vb_lock);
>> +
>> + if (type != q->type) {
>> + dprintk(1, "streamon: invalid stream type\n");
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> +
>> + if (q->streaming) {
>> + dprintk(1, "streamon: already streaming\n");
>> + ret = -EBUSY;
>> + goto done;
>> + }
>> +
>> + /*
>> + * Cannot start streaming on an OUTPUT device if no buffers have
>> + * been queued yet.
>> + */
>> + if (V4L2_TYPE_IS_OUTPUT(q->type)) {
>> + if (list_empty(&q->queued_list)) {
>> + dprintk(1, "streamon: no output buffers queued\n");
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> + }
>> +
>> + q->streaming = 1;
>> +
>> + /*
>> + * If any buffers were queued before streamon,
>> + * we can now pass them to driver for processing.
>> + */
>> + list_for_each_entry(vb,&q->queued_list, queued_entry)
>> + __enqueue_in_driver(vb);
>> +
>> + dprintk(3, "Streamon successful\n");
>> +done:
>> + mutex_unlock(&q->vb_lock);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_streamon);
>> +
>> +/**
>> + * __vb2_queue_cancel() - cancel and stop (pause) streaming
>> + *
>> + * Removes all queued buffers from driver's queue and all buffers queued by
>> + * userspace from videobuf's queue. Returns to state after reqbufs.
>> + */
>> +static void __vb2_queue_cancel(struct vb2_queue *q)
>> +{
>> + unsigned long flags = 0;
>> + int i;
>> +
>> + q->streaming = 0;
>> +
>> + /*
>> + * Remove buffers from driver's queue. If a hardware operation
>> + * is currently underway, drv_lock should be claimed and we will
>> + * have to wait for it to finish before taking back buffers.
>> + */
>> + spin_lock_irqsave(q->drv_lock, flags);
>> + for (i = 0; i< q->num_buffers; ++i) {
>> + if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
>> + list_del(&q->bufs[i]->drv_entry);
>> + q->bufs[i]->state = VB2_BUF_STATE_DEQUEUED;
>> + }
>> + spin_unlock_irqrestore(q->drv_lock, flags);
>
> I feel that this spinlock is too simplistic. I think we need a new op:
> stop_streaming() or something like that. The driver will stop any streaming
> and dequeue any active buffers. And if necessary it has to wait for any DMA
> in progress to finish first.
>
> That will also make it possible to remove the drv_lock altogether and make the
> driver responsible for proper locking in buf_queue and stop_streaming.
>
The purpose of drv_lock is basically to properly handle cancelling. So yes, if we
add such an op, it'd become obsolete. Drivers would have to manage that spinlock
themselves. I'm trying to see all the implications, I'll try reimplementing it
to get a better picture.
> Actually, it might also be an idea to implement a start_streaming op for symmetry.
>
There is actually another thing to consider here. We had a thorough discussion with
Laurent about this, which I'm afraid I don't recall well enough at the moment though.
When vidioc_streamon in driver is called and buffers were previously queued, videobuf
calls buffer_queue in driver as well, so it can begin processing immediately. The
problem is though that the driver has to actually activate the device somewhere during
that time as well. We have two main scenarios:
driver_vidioc_streamon()
{
activate_device();
vb2_streamon();
}
or
driver_vidioc_streamon()
{
vb2_streamon();
activate_device();
}
Now in case (1), the buffers will be passed to the driver by vb after the device
is activated. This might not be good, since some devices may require buffers to be
ready before they can be activated. In case (2) on the other hand, streamon will
call the buffer_queue callback which now needs to know whether it has been called
from streamon or from a later qbuf. There are also issues with buffer_queue being
called with a spinlock held. I'm probably missing something right now, but maybe
introducing that start_streaming callback and at the same time getting rid of the
driver spinlock might help, somehow.
>> +
>> + /*
>> + * Remove all buffers from videobuf's list...
>> + */
>> + INIT_LIST_HEAD(&q->queued_list);
>> + /*
>> + * ...and done list; userspace will not receive any buffers it
>> + * has not already dequeued before initiating cancel.
>> + */
>> + INIT_LIST_HEAD(&q->done_list);
>
> Is this correct? Shouldn't put_userptr be called for all queued and done buffers?
>
queue_cancel is used for pausing. Since we do not want to free memory on pause,
I thought that the symmetrical thing to do here in case of userptr is not put()ing
memory when pausing either. Put is called on close (release) or on reqbufs(0).
>> + wake_up_interruptible_all(&q->done_wq);
>> +}
>> +
>> +/**
>> + * vb2_streamoff - stop streaming
>> + * @q: videobuf2 queue
>> + * @type: type argument passed from userspace to vidioc_streamoff handler
>> + *
>> + * Should be called from vidioc_streamoff handler of a driver.
>> + * This function:
>> + * 1) verifies current state,
>> + * 2) stop streaming and dequeues any queued buffers, including those previously
>> + * passed to the driver (after waiting for the driver to finish).
>> + *
>> + * This call can be used for pausing playback.
>> + * The return values from this function are intended to be directly returned
>> + * from vidioc_streamoff handler in the driver
>> + */
>> +int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
>> +{
>> + int ret = 0;
>> +
>> + mutex_lock(&q->vb_lock);
>> +
>> + if (type != q->type) {
>> + dprintk(1, "streamoff: invalid stream type\n");
>> + ret = -EINVAL;
>> + goto end;
>> + }
>> +
>> + if (!q->streaming) {
>> + dprintk(1, "streamoff: not streaming\n");
>> + ret = -EINVAL;
>> + goto end;
>> + }
>> +
>> + /*
>> + * Cancel will pause streaming and remove all buffers from the driver
>> + * and videobuf, effectively returning control over them to userspace.
>> + */
>> + __vb2_queue_cancel(q);
>> +
>> + dprintk(3, "Streamoff successful\n");
>> +end:
>> + mutex_unlock(&q->vb_lock);
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_streamoff);
>
> <snip>
>
> Some general remarks:
>
> 1) It is probably useful to add a simply inline function like this:
>
> static inline bool vb2_is_streaming(struct vb2_queue *q)
> {
> return q->streaming;
> }
>
Yes, good point.
> 2) We need very clear documentation detailing:
>
> - where the struct vb2_queue has to be stored (it should be associated with the
> video_device struct or the v4l2_device struct if there is only one queue).
I don't think vb2 needs to be aware with what it is "associated" with. Does/should it
make any difference for vb2?
> - when to call vb2_queue_init (before registering the device node, I think).
No constraints on how early it can be called, basically yes.
> - when to call vb2_queue_release (after unregistering the device node? Does that
> also work well with USB devices after a disconnect? I think it is OK, but I'm
> not 100% certain.)
Not sure about how USB devices work in this matter...
> - how does it work if multiple file handles are open? If fh A calls REQBUFS, is fh
> B allowed to call it again? My feeling is that once a fh calls REQBUFS, the
> queue is associated with that fh until REQBUFS with count == 0 is called, or
> until the fh is closed. All the other streaming ioctls should be called from
> that fh. To implement this reqbufs should be passed a struct file (or a v4l2_fh?).
> And for the others we either need this as well or we add a simple inline function
> checking this that drivers can call.
Basically, if you call reqbufs multiple times, it will work as expected, i.e. will
free or reallocate memory.
vb2 doesn't have any notion of video devices, file handles, etc. Do you think it should?
It just does whatever driver passes to it, of course making sure everything stays in
a sane state (e.g. you can't allocate memory twice, or free memory when streaming).
I think the state machine in vb2 is complicated enough. If we need more advanced,
file handle-aware state machine, maybe a higher-level module should be introduced for that,
something that would build up on vb2, like mem2mem does?
I think you might be thinking of vb2 as of a more complicated framework that it really is.
I was trying to make it as compact as possible, so that it would provide fundamentals to
later built on if needed: e.g. if we needed a mem2mem-like capability, we'd use mem2mem
that would be adding additional constraints and features built on vb2, if we needed
something else, we'd have a different module for that, also utilizing the basic vb2
framework. What is your opinion on that?
>
> 3) Read/write will have its own issues: if the driver supports read/write, then
> some internal checks are needed: once reqbufs was called on a fh, read/write
> should not be allowed (until REQBUFS(0), that is). The same is true vice versa,
> except that once you've started reading or writing the only way to go back to
> streaming I/O is by closing the fh first.
>
Yes, that is basically it, to sum up:
REQBUFS(n) - ... - REQBUFS(0) - read/write allowed
REQBUFS(n) - ... - read/write disallowed
REQBUFS(n) - ... - close - open - read/write allowed
read/write - close - open - REQBUFS(0) - allowed
read/write - REQBUFS(0) - disallowed
> 4) If poll is called without a preceding reqbufs or read, then it should initiate
> streaming and mark the queue as being in read (or write) mode. It's the way poll
> is supposed to work for read or write.
>
Ok.
> 5) Allowing mixing of read/write and streaming I/O. I am very much opposed to this.
> First of all it will cause skipped frames since read will steal from dqbuf (or
> vice versa, depending on how you look at it). Once you start to read it will also
> be impossible to use REQBUFS(0), and the internal administration will be a nightmare.
> Frankly, I don't think there is a way to implement this in a way that makes sense.
> We should probably investigate those utilities that are supposed to do this.
> I understand that they are xawtv and xdtv.
>
I know Mauro would like to see this, but I'm not really keen on it either. But I'm thinking
of a different way to do that: introduce two videobuf queues and let driver multiplex among
them, which would basically mean initializing both queues on open, setting up formats on both
at the same time, etc., and passing read calls to one of the queues and streaming calls to
the other. Of course this would result in frame dropping...
@@ -48,6 +48,9 @@ config VIDEO_TUNER
config V4L2_MEM2MEM_DEV
tristate
depends on VIDEOBUF_GEN
+config VIDEOBUF2_CORE
+ tristate
+
#
# Multimedia Video device configuration
@@ -117,6 +117,8 @@ obj-$(CONFIG_VIDEOBUF_VMALLOC) += videobuf-vmalloc.o
obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
obj-$(CONFIG_VIDEO_BTCX) += btcx-risc.o
+obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
+
obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
obj-$(CONFIG_VIDEO_M32R_AR_M64278) += arv.o
new file mode 100644
@@ -0,0 +1,1457 @@
+/*
+ * videobuf2-core.c - V4L2 driver helper framework
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Pawel Osciak <p.osciak@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <linux/poll.h>
+
+#include <media/videobuf2-core.h>
+
+static int debug;
+module_param(debug, int, 0644);
+
+#define dprintk(level, fmt, arg...) \
+ do { \
+ if (debug >= level) \
+ printk(KERN_DEBUG "vb2: " fmt, ## arg); \
+ } while (0)
+
+#define mem_ops(q, plane) ((q)->alloc_ctx[plane]->mem_ops)
+
+#define call_memop(q, plane, op, args...) \
+ ((q)->alloc_ctx[plane]->mem_ops->op) ? \
+ ((q)->alloc_ctx[plane]->mem_ops->op(args)) : 0
+
+
+/**
+ * __vb2_buf_mem_alloc() - allocate video memory for the given buffer
+ */
+static int __vb2_buf_mem_alloc(struct vb2_buffer *vb,
+ unsigned long *plane_sizes)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ void *mem_priv;
+ int plane;
+
+ /* Allocate memory for all planes in this buffer */
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ mem_priv = call_memop(q, plane, alloc, q->alloc_ctx[plane],
+ plane_sizes[plane]);
+ if (!mem_priv)
+ goto free;
+
+ /* Associate allocator private data with this plane */
+ vb->planes[plane].mem_priv = mem_priv;
+ vb->v4l2_planes[plane].length = plane_sizes[plane];
+ }
+
+ return 0;
+free:
+ /* Free already allocated memory if one of the allocations failed */
+ for (; plane > 0; --plane)
+ call_memop(q, plane, put, vb->planes[plane - 1].mem_priv);
+
+ return -ENOMEM;
+}
+
+/**
+ * __vb2_buf_mem_free() - free memory of the given buffer
+ */
+static void __vb2_buf_mem_free(struct vb2_buffer *vb)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ unsigned int plane;
+
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ call_memop(q, plane, put, vb->planes[plane].mem_priv);
+ dprintk(3, "Freed plane %d of buffer %d\n",
+ plane, vb->v4l2_buf.index);
+ }
+}
+
+/**
+ * __vb2_buf_userptr_put() - release userspace memory associated associated
+ * with a USERPTR buffer
+ */
+static void __vb2_buf_userptr_put(struct vb2_buffer *vb)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ unsigned int plane;
+
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ call_memop(q, plane, put_userptr, vb->planes[plane].mem_priv);
+ vb->planes[plane].mem_priv = NULL;
+ }
+}
+
+/**
+ * __setup_offsets() - setup unique offsets ("cookies") for every plane in
+ * every buffer on the queue
+ */
+static void __setup_offsets(struct vb2_queue *q)
+{
+ unsigned int buffer, plane;
+ struct vb2_buffer *vb;
+ unsigned long off = 0;
+
+ for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+ vb = q->bufs[buffer];
+ if (!vb)
+ continue;
+
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ vb->v4l2_planes[plane].m.mem_offset = off;
+
+ dprintk(3, "Buffer %d, plane %d offset 0x%08lx\n",
+ buffer, plane, off);
+
+ off += vb->v4l2_planes[plane].length;
+ off = PAGE_ALIGN(off);
+ }
+ }
+}
+
+/**
+ * __vb2_queue_alloc() - allocate videobuf buffer structures and (for MMAP type)
+ * video buffer memory for all buffers/planes on the queue and initializes the
+ * queue
+ *
+ * Returns the number of buffers successfully allocated.
+ */
+static int __vb2_queue_alloc(struct vb2_queue *q, enum v4l2_memory memory,
+ unsigned int num_buffers, unsigned int num_planes)
+{
+ unsigned long plane_sizes[VIDEO_MAX_PLANES];
+ unsigned int buffer, plane;
+ struct vb2_buffer *vb;
+ int ret;
+
+ /* Get requested plane sizes from the driver */
+ for (plane = 0; plane < num_planes; ++plane) {
+ ret = q->ops->plane_setup(q, plane, &plane_sizes[plane]);
+ if (ret) {
+ dprintk(1, "Plane setup failed\n");
+ return ret;
+ }
+ }
+
+ for (buffer = 0; buffer < num_buffers; ++buffer) {
+ /* Allocate videobuf buffer structures */
+ vb = kzalloc(sizeof(struct vb2_buffer), GFP_KERNEL);
+ if (!vb) {
+ dprintk(1, "Memory alloc for buffer struct failed\n");
+ break;
+ }
+
+ /* Length stores number of planes for multiplanar buffers */
+ if (V4L2_TYPE_IS_MULTIPLANAR(q->type))
+ vb->v4l2_buf.length = num_planes;
+
+ vb->state = VB2_BUF_STATE_DEQUEUED;
+ vb->vb2_queue = q;
+ vb->num_planes = num_planes;
+ vb->v4l2_buf.index = buffer;
+ vb->v4l2_buf.type = q->type;
+ vb->v4l2_buf.memory = memory;
+
+ /* Allocate video buffer memory for the MMAP type */
+ if (memory == V4L2_MEMORY_MMAP) {
+ ret = __vb2_buf_mem_alloc(vb, plane_sizes);
+ if (ret) {
+ dprintk(1, "Failed allocating memory for "
+ "buffer %d\n", buffer);
+ kfree(vb);
+ break;
+ }
+ /*
+ * Call the driver-provided buffer initialization
+ * callback, if given. An error in initialization
+ * results in queue setup failure.
+ */
+ if (q->ops->buf_init) {
+ ret = q->ops->buf_init(vb);
+ if (ret) {
+ dprintk(1, "Buffer %d %p initialization"
+ " failed\n", buffer, vb);
+ __vb2_buf_mem_free(vb);
+ kfree(vb);
+ break;
+ }
+ }
+ }
+
+ q->bufs[buffer] = vb;
+ }
+
+ q->num_buffers = buffer;
+
+ __setup_offsets(q);
+
+ dprintk(1, "Allocated %d buffers, %d plane(s) each\n",
+ q->num_buffers, num_planes);
+
+ return buffer;
+}
+
+/**
+ * __vb2_free_mem() - release all video buffer memory for a given queue
+ */
+static void __vb2_free_mem(struct vb2_queue *q)
+{
+ unsigned int buffer;
+ struct vb2_buffer *vb;
+
+ for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+ vb = q->bufs[buffer];
+ if (!vb)
+ continue;
+
+ /* Free MMAP buffers or release USERPTR buffers */
+ if (q->memory == V4L2_MEMORY_MMAP)
+ __vb2_buf_mem_free(vb);
+ else
+ __vb2_buf_userptr_put(vb);
+ }
+}
+
+/**
+ * __vb2_queue_free() - free the queue - video memory and related information
+ * and return the queue to an uninitialized state
+ */
+static int __vb2_queue_free(struct vb2_queue *q)
+{
+ unsigned int buffer;
+
+ /* Call driver-provided cleanup function for each buffer, if provided */
+ if (q->ops->buf_cleanup) {
+ for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+ if (NULL == q->bufs[buffer])
+ continue;
+ q->ops->buf_cleanup(q->bufs[buffer]);
+ }
+ }
+
+ /* Release video buffer memory */
+ __vb2_free_mem(q);
+
+ /* Free videobuf buffers */
+ for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+ if (NULL == q->bufs[buffer])
+ continue;
+ kfree(q->bufs[buffer]);
+ q->bufs[buffer] = NULL;
+ }
+
+ q->num_buffers = 0;
+ q->memory = 0;
+
+ return 0;
+}
+
+/**
+ * __verify_planes_array() - verify that the planes array passed in struct
+ * v4l2_buffer from userspace can be safely used
+ */
+static int __verify_planes_array(struct vb2_buffer *vb, struct v4l2_buffer *b)
+{
+ /* Is memory for copying plane information present? */
+ if (NULL == b->m.planes) {
+ dprintk(1, "Multi-planar buffer passed but "
+ "planes array not provided\n");
+ return -EINVAL;
+ }
+
+ if (b->length < vb->num_planes || b->length > VIDEO_MAX_PLANES) {
+ dprintk(1, "Incorrect planes array length, "
+ "expected %d, got %d\n", vb->num_planes, b->length);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/**
+ * __fill_v4l2_buffer() - fill in a struct v4l2_buffer with information to be
+ * returned to userspace
+ */
+static int __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ int ret = 0;
+
+ /* Copy back data such as timestamp, input, etc. */
+ memcpy(b, &vb->v4l2_buf, offsetof(struct v4l2_buffer, m));
+ b->input = vb->v4l2_buf.input;
+ b->reserved = vb->v4l2_buf.reserved;
+
+ if (V4L2_TYPE_IS_MULTIPLANAR(q->type)) {
+ ret = __verify_planes_array(vb, b);
+ if (ret)
+ return ret;
+
+ /*
+ * Fill in plane-related data if userspace provided an array
+ * for it. The memory and size is verified above.
+ */
+ memcpy(b->m.planes, vb->v4l2_planes,
+ b->length * sizeof(struct v4l2_plane));
+ } else {
+ /*
+ * We use length and offset in v4l2_planes array even for
+ * single-planar buffers, but userspace does not.
+ */
+ b->length = vb->v4l2_planes[0].length;
+ if (q->memory == V4L2_MEMORY_MMAP)
+ b->m.offset = vb->v4l2_planes[0].m.mem_offset;
+ }
+
+ b->flags = 0;
+
+ switch (vb->state) {
+ case VB2_BUF_STATE_QUEUED:
+ case VB2_BUF_STATE_ACTIVE:
+ b->flags |= V4L2_BUF_FLAG_QUEUED;
+ break;
+ case VB2_BUF_STATE_ERROR:
+ b->flags |= V4L2_BUF_FLAG_ERROR;
+ /* fall through */
+ case VB2_BUF_STATE_DONE:
+ b->flags |= V4L2_BUF_FLAG_DONE;
+ break;
+ case VB2_BUF_STATE_DEQUEUED:
+ /* nothing */
+ break;
+ }
+
+ if (vb->num_planes_mapped == vb->num_planes)
+ b->flags |= V4L2_BUF_FLAG_MAPPED;
+
+ return ret;
+}
+
+/**
+ * vb2_querybuf() - query video buffer information
+ * @q: videobuf queue
+ * @b: buffer struct passed from userspace to vidioc_querybuf handler
+ * in driver
+ *
+ * Should be called from vidioc_querybuf ioctl handler in driver.
+ * This function will verify the passed v4l2_buffer structure and fill the
+ * relevant information for the userspace.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_querybuf handler in driver.
+ */
+int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
+{
+ struct vb2_buffer *vb;
+ int ret = -EINVAL;
+
+ mutex_lock(&q->vb_lock);
+
+ if (b->type != q->type) {
+ dprintk(1, "querybuf: wrong buffer type\n");
+ goto done;
+ }
+
+ if (b->index >= q->num_buffers) {
+ dprintk(1, "querybuf: buffer index out of range\n");
+ goto done;
+ }
+ vb = q->bufs[b->index];
+ if (NULL == vb) {
+ /* Should never happen */
+ dprintk(1, "querybuf: no such buffer\n");
+ goto done;
+ }
+
+ ret = __fill_v4l2_buffer(vb, b);
+done:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL(vb2_querybuf);
+
+/**
+ * __verify_userptr_ops() - verify that all memory operations required for
+ * USERPTR queue type have been provided
+ */
+static int __verify_userptr_ops(struct vb2_queue *q, unsigned int num_planes)
+{
+ unsigned int i;
+
+ for (i = 0; i < num_planes; ++i)
+ if (!mem_ops(q, i)->get_userptr || !mem_ops(q, i)->put_userptr)
+ return -EINVAL;
+
+ return 0;
+}
+
+/**
+ * __verify_mmap_ops() - verify that all memory operations required for
+ * MMAP queue type have been provided
+ */
+static int __verify_mmap_ops(struct vb2_queue *q, unsigned int num_planes)
+{
+ unsigned int i;
+
+ for (i = 0; i < num_planes; ++i)
+ if (!mem_ops(q, i)->alloc || !mem_ops(q, i)->put
+ || !mem_ops(q, i)->mmap)
+ return -EINVAL;
+
+ return 0;
+}
+
+/**
+ * __buffers_in_use() - return true if any buffers on the queue are in use and
+ * the queue cannot be freed (by the means of REQBUFS(0)) call
+ */
+static bool __buffers_in_use(struct vb2_queue *q)
+{
+ unsigned int buffer, plane;
+ struct vb2_buffer *vb;
+
+ for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+ vb = q->bufs[buffer];
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ /*
+ * If num_users() has not been provided, apparently
+ * nobody cares.
+ */
+ if (!mem_ops(q, plane)->num_users)
+ continue;
+
+ /*
+ * If num_users() returns more than 1, we are not the
+ * only user of the plane's memory.
+ */
+ if (call_memop(q, plane, num_users,
+ vb->planes[plane].mem_priv) > 1)
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/**
+ * vb2_reqbufs() - Initiate streaming
+ * @q: videobuf2 queue
+ * @req: struct passed from userspace to vidioc_reqbufs handler in driver
+ *
+ * Should be called from vidioc_reqbufs ioctl handler of a driver.
+ * This function:
+ * 1) verifies streaming parameters passed from the userspace,
+ * 2) sets up the queue,
+ * 3) negotiates number of buffers and planes per buffer with the driver
+ * to be used during streaming,
+ * 4) allocates internal buffer structures (struct vb2_buffer), according to
+ * the agreed parameters,
+ * 5) for MMAP memory type, allocates actual video memory, using the
+ * memory handling/allocation routines provided during queue initialization
+ *
+ * If req->count is 0, all the memory will be freed instead.
+ * If the queue has been allocated previously (by a previous vb2_reqbufs) call
+ * and the queue is not busy, memory will be reallocated.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_reqbufs handler in driver.
+ */
+int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
+{
+ unsigned int num_buffers, num_planes;
+ int ret = 0;
+
+ if (req->memory != V4L2_MEMORY_MMAP
+ && req->memory != V4L2_MEMORY_USERPTR) {
+ dprintk(1, "reqbufs: unsupported memory type\n");
+ return -EINVAL;
+ }
+
+ mutex_lock(&q->vb_lock);
+
+ if (req->type != q->type) {
+ dprintk(1, "reqbufs: queue type invalid\n");
+ ret = -EINVAL;
+ goto end;
+ }
+
+ if (q->streaming) {
+ dprintk(1, "reqbufs: streaming active\n");
+ ret = -EBUSY;
+ goto end;
+ }
+
+ if (req->count == 0) {
+ /* Free/release memory for count = 0, but only if unused */
+ if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) {
+ dprintk(1, "reqbufs: memory in use, cannot free\n");
+ ret = -EBUSY;
+ goto end;
+ }
+
+ ret = __vb2_queue_free(q);
+ goto end;
+ }
+
+ if (q->num_buffers != 0) {
+ /*
+ * We already have buffers allocated, so a reallocation is
+ * required, but only if the buffers are not in use.
+ */
+ if (q->memory == V4L2_MEMORY_MMAP && __buffers_in_use(q)) {
+ dprintk(1, "reqbufs: memory in use, "
+ "cannot reallocate\n");
+ ret = -EBUSY;
+ goto end;
+ }
+
+ ret = __vb2_queue_free(q);
+ if (ret)
+ goto end;
+ }
+
+ num_buffers = min_t(unsigned int, req->count, VIDEO_MAX_FRAME);
+
+ /* Ask the driver how many buffers and planes per buffer it requires */
+ ret = q->ops->queue_negotiate(q, &num_buffers, &num_planes);
+ if (ret)
+ goto end;
+
+ /*
+ * Make sure all the required memory ops for given memory type
+ * are available.
+ */
+ if (req->memory == V4L2_MEMORY_MMAP
+ && __verify_mmap_ops(q, num_planes)) {
+ dprintk(1, "reqbufs: MMAP for current setup unsupported\n");
+ ret = -EINVAL;
+ goto end;
+ } else if (req->memory == V4L2_MEMORY_USERPTR
+ && __verify_userptr_ops(q, num_planes)) {
+ dprintk(1, "reqbufs: USERPTR for current setup unsupported\n");
+ ret = -EINVAL;
+ goto end;
+ }
+
+ /* Finally, allocate buffers and video memory */
+ ret = __vb2_queue_alloc(q, req->memory, num_buffers, num_planes);
+ if (ret < 0) {
+ dprintk(1, "Memory allocation failed with error: %d\n", ret);
+ } else {
+ /*
+ * Return the number of successfully allocated buffers
+ * to the userspace.
+ */
+ req->count = ret;
+ ret = 0;
+ }
+
+ q->memory = req->memory;
+
+end:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_reqbufs);
+
+/**
+ * vb2_plane_vaddr() - Return a kernel virtual address of a given plane
+ * @vb: vb2_buffer to which the plane in question belongs to
+ * @plane_no: plane number for which the address is to be returned
+ *
+ * This function returns a kernel virtual address of a given plane if
+ * such a mapping exist, NULL otherwise.
+ */
+void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+
+ if (plane_no > vb->num_planes)
+ return NULL;
+
+ return call_memop(q, plane_no, vaddr, vb->planes[plane_no].mem_priv);
+
+}
+EXPORT_SYMBOL_GPL(vb2_plane_vaddr);
+
+/**
+ * vb2_plane_paddr() - Return the physical address of a given plane
+ * @vb: vb2_buffer to which the plane in question belongs to
+ * @plane_no: plane number for which the address is to be returned
+ *
+ * This function returns a physical address of a given plane if available,
+ * NULL otherwise.
+ */
+unsigned long vb2_plane_paddr(struct vb2_buffer *vb, unsigned int plane_no)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+
+ if (plane_no > vb->num_planes)
+ return 0UL;
+
+ return call_memop(q, plane_no, paddr, vb->planes[plane_no].mem_priv);
+}
+EXPORT_SYMBOL_GPL(vb2_plane_paddr);
+
+/**
+ * vb2_buffer_done() - inform videobuf that an operation on a buffer is finished
+ * @vb: vb2_buffer returned from the driver
+ * @state: either VB2_BUF_STATE_DONE if the operation finished successfully
+ * or VB2_BUF_STATE_ERROR if the operation finished with an error
+ *
+ * This function should be called by the driver after a hardware operation on
+ * a buffer is finished and the buffer may be returned to userspace. The driver
+ * cannot use this buffer anymore until it is queued back to it by videobuf
+ * by the means of buf_queue callback. Only buffers previously queued to the
+ * driver by buf_queue can be passed to this function.
+ */
+void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ unsigned long flags;
+
+ if (vb->state != VB2_BUF_STATE_ACTIVE)
+ return;
+
+ if (state != VB2_BUF_STATE_DONE && state != VB2_BUF_STATE_ERROR)
+ return;
+
+ dprintk(4, "Done processing on buffer %d, state: %d\n",
+ vb->v4l2_buf.index, vb->state);
+
+ /* Add the buffer to the done buffers list */
+ spin_lock_irqsave(&q->done_lock, flags);
+ vb->state = state;
+ list_add_tail(&vb->done_entry, &q->done_list);
+ spin_unlock_irqrestore(&q->done_lock, flags);
+
+ /* Inform any processes that may be waiting for buffers */
+ wake_up_interruptible(&q->done_wq);
+}
+EXPORT_SYMBOL_GPL(vb2_buffer_done);
+
+/**
+ * __fill_vb2_buffer() - fill a vb2_buffer with information provided in
+ * a v4l2_buffer by the userspace
+ */
+static int __fill_vb2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b,
+ struct v4l2_plane *v4l2_planes)
+{
+ unsigned int plane;
+ int ret;
+
+ if (V4L2_TYPE_IS_MULTIPLANAR(b->type)) {
+ /*
+ * Verify that the userspace gave us a valid array for
+ * plane information.
+ */
+ ret = __verify_planes_array(vb, b);
+ if (ret)
+ return ret;
+
+ /* Fill in driver-provided information for OUTPUT types */
+ if (V4L2_TYPE_IS_OUTPUT(b->type)) {
+ /*
+ * Will have to go up to b->length when API starts
+ * accepting variable number of planes.
+ */
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ v4l2_planes[plane].bytesused =
+ b->m.planes[plane].bytesused;
+ v4l2_planes[plane].data_offset =
+ b->m.planes[plane].data_offset;
+ }
+ }
+
+ if (b->memory == V4L2_MEMORY_USERPTR) {
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ v4l2_planes[plane].m.userptr =
+ b->m.planes[plane].m.userptr;
+ v4l2_planes[plane].length =
+ b->m.planes[plane].length;
+ }
+ }
+ } else {
+ /*
+ * Single-planar buffers do not use planes array,
+ * so fill in relevant v4l2_buffer struct fields instead.
+ * In videobuf we use our internal V4l2_planes struct for
+ * single-planar buffers as well, for simplicity.
+ */
+ if (V4L2_TYPE_IS_OUTPUT(b->type))
+ v4l2_planes[0].bytesused = b->bytesused;
+
+ if (b->memory == V4L2_MEMORY_USERPTR) {
+ v4l2_planes[0].m.userptr = b->m.userptr;
+ v4l2_planes[0].length = b->length;
+ }
+ }
+
+ vb->v4l2_buf.field = b->field;
+ vb->v4l2_buf.timestamp = b->timestamp;
+
+ return 0;
+}
+
+/**
+ * __qbuf_userptr() - handle qbuf of a USERPTR buffer
+ */
+static int __qbuf_userptr(struct vb2_buffer *vb, struct v4l2_buffer *b)
+{
+ struct v4l2_plane planes[VIDEO_MAX_PLANES];
+ struct vb2_queue *q = vb->vb2_queue;
+ void *mem_priv = NULL;
+ unsigned int plane;
+ int ret;
+
+ /* Verify and copy relevant information provided by the userspace */
+ ret = __fill_vb2_buffer(vb, b, planes);
+ if (ret)
+ return ret;
+
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ /* Skip the plane if already verified */
+ if (vb->v4l2_planes[plane].m.userptr == planes[plane].m.userptr
+ && vb->v4l2_planes[plane].length == planes[plane].length)
+ continue;
+
+ dprintk(3, "qbuf: userspace address for plane %d changed, "
+ "reacquiring memory\n", plane);
+
+ /* Release previously acquired memory if present */
+ if (vb->planes[plane].mem_priv)
+ call_memop(q, plane, put_userptr,
+ vb->planes[plane].mem_priv);
+
+ vb->planes[plane].mem_priv = NULL;
+
+ /* Acquire each plane's memory */
+ if (mem_ops(q, plane)->get_userptr) {
+ mem_priv = mem_ops(q, plane)->get_userptr(
+ planes[plane].m.userptr,
+ planes[plane].length);
+ if (IS_ERR(mem_priv)) {
+ dprintk(1, "qbuf: failed acquiring userspace "
+ "memory for plane %d\n", plane);
+ goto err;
+ }
+
+ vb->planes[plane].mem_priv = mem_priv;
+ }
+ }
+
+ /*
+ * Call driver-specific initialization on the newly acquired buffer,
+ * if provided.
+ */
+ if (q->ops->buf_init) {
+ ret = q->ops->buf_init(vb);
+ if (ret) {
+ dprintk(1, "qbuf: buffer initialization failed\n");
+ goto err;
+ }
+ }
+
+ /*
+ * Now that everything is in order, copy relevant information
+ * provided by userspace.
+ */
+ for (plane = 0; plane < vb->num_planes; ++plane)
+ vb->v4l2_planes[plane] = planes[plane];
+
+ return 0;
+err:
+ /* In case of errors, release planes that were already acquired */
+ for (; plane > 0; --plane) {
+ call_memop(q, plane, put_userptr,
+ vb->planes[plane - 1].mem_priv);
+ vb->planes[plane - 1].mem_priv = NULL;
+ }
+
+ return ret;
+}
+
+/**
+ * __qbuf_mmap() - handle qbuf of an MMAP buffer
+ */
+static int __qbuf_mmap(struct vb2_buffer *vb, struct v4l2_buffer *b)
+{
+ return __fill_vb2_buffer(vb, b, vb->v4l2_planes);
+}
+
+/**
+ * __enqueue_in_driver() - enqueue a vb2_buffer in driver for processing
+ */
+static void __enqueue_in_driver(struct vb2_buffer *vb)
+{
+ struct vb2_queue *q = vb->vb2_queue;
+ unsigned long flags;
+
+ spin_lock_irqsave(q->drv_lock, flags);
+ vb->state = VB2_BUF_STATE_ACTIVE;
+ q->ops->buf_queue(vb);
+ spin_unlock_irqrestore(q->drv_lock, flags);
+}
+
+/**
+ * vb2_qbuf() - Queue a buffer from userspace
+ * @q: videobuf2 queue
+ * @b: buffer structure passed from userspace to vidioc_qbuf handler
+ * in driver
+ *
+ * Should be called from vidioc_qbuf ioctl handler of a driver.
+ * This function:
+ * 1) verifies the passed buffer,
+ * 2) calls buf_prepare callback in the driver (if provided), in which
+ * driver-specific buffer initialization can be performed,
+ * 3) if streaming is on, queues the buffer in driver by the means of buf_queue
+ * callback for processing.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_qbuf handler in driver.
+ */
+int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b)
+{
+ struct vb2_buffer *vb;
+ int ret;
+
+ mutex_lock(&q->vb_lock);
+
+ ret = -EINVAL;
+ if (b->type != q->type) {
+ dprintk(1, "qbuf: invalid buffer type\n");
+ goto done;
+ }
+ if (b->index >= q->num_buffers) {
+ dprintk(1, "qbuf: buffer index out of range\n");
+ goto done;
+ }
+
+ vb = q->bufs[b->index];
+ if (NULL == vb) {
+ /* Should never happen */
+ dprintk(1, "qbuf: buffer is NULL\n");
+ goto done;
+ }
+
+ if (b->memory != q->memory) {
+ dprintk(1, "qbuf: invalid memory type\n");
+ goto done;
+ }
+
+ if (vb->state != VB2_BUF_STATE_DEQUEUED) {
+ dprintk(1, "qbuf: buffer already in use\n");
+ goto done;
+ }
+
+ if (q->memory == V4L2_MEMORY_MMAP)
+ ret = __qbuf_mmap(vb, b);
+ else if (q->memory == V4L2_MEMORY_USERPTR)
+ ret = __qbuf_userptr(vb, b);
+ if (ret)
+ goto done;
+
+ if (q->ops->buf_prepare) {
+ ret = q->ops->buf_prepare(vb);
+ if (ret) {
+ dprintk(1, "qbuf: buffer preparation failed\n");
+ goto done;
+ }
+ }
+
+ /*
+ * Add to the queued buffers list, a buffer will stay on it until
+ * dequeued in dqbuf.
+ */
+ list_add_tail(&vb->queued_entry, &q->queued_list);
+ vb->state = VB2_BUF_STATE_QUEUED;
+
+ /*
+ * If already streaming, give the buffer to driver for processing.
+ * If not, the buffer will be given to driver on next streamon.
+ */
+ if (q->streaming)
+ __enqueue_in_driver(vb);
+
+ dprintk(1, "qbuf of buffer %d succeeded\n", vb->v4l2_buf.index);
+ ret = 0;
+done:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_qbuf);
+
+/**
+ * __vb2_wait_for_done_vb() - wait for a buffer to become available
+ * for dequeuing
+ *
+ * Will sleep if required for nonblocking == false.
+ */
+static int __vb2_wait_for_done_vb(struct vb2_queue *q, int nonblocking)
+{
+ int retval = 0;
+
+checks:
+ if (!q->streaming) {
+ dprintk(1, "Streaming off, will not wait for buffers\n");
+ retval = -EINVAL;
+ goto end;
+ }
+
+ /*
+ * Buffers may be added to vb_done_list without holding the vb_lock,
+ * but removal is performed only while holding both vb_lock and the
+ * vb_done_lock spinlock. Thus we can be sure that as long as we hold
+ * vb_lock, the list will remain not empty if this check succeeds.
+ */
+ if (list_empty(&q->done_list)) {
+ if (nonblocking) {
+ dprintk(1, "Nonblocking and no buffers to dequeue, "
+ "will not wait\n");
+ retval = -EAGAIN;
+ goto end;
+ }
+
+ /*
+ * We are streaming and nonblocking, wait for another buffer to
+ * become ready or for streamoff. vb_lock is released to allow
+ * streamoff or qbuf to be called while waiting.
+ */
+ mutex_unlock(&q->vb_lock);
+ /*
+ * Although the mutex is released here, we will be reevaluating
+ * both conditions again after reacquiring it.
+ */
+ dprintk(3, "Will sleep waiting for buffers\n");
+ retval = wait_event_interruptible(q->done_wq,
+ !list_empty(&q->done_list) || !q->streaming);
+ mutex_lock(&q->vb_lock);
+
+ if (retval)
+ goto end;
+
+ goto checks;
+ }
+
+end:
+ return retval;
+}
+
+/**
+ * __vb2_get_done_vb() - get a buffer ready for dequeuing
+ *
+ * Will sleep if required for nonblocking == false.
+ */
+static int __vb2_get_done_vb(struct vb2_queue *q, struct vb2_buffer **vb,
+ int nonblocking)
+{
+ unsigned long flags;
+ int ret = 0;
+
+ /*
+ * Wait for at least one buffer to become available on the done_list.
+ */
+ ret = __vb2_wait_for_done_vb(q, nonblocking);
+ if (ret)
+ goto end;
+
+ /*
+ * vb_lock has been held since we last verified that done_list is
+ * not empty, so no need for another list_empty(done_list) check.
+ */
+ spin_lock_irqsave(&q->done_lock, flags);
+ *vb = list_first_entry(&q->done_list, struct vb2_buffer, done_entry);
+ list_del(&(*vb)->done_entry);
+ spin_unlock_irqrestore(&q->done_lock, flags);
+
+end:
+ return ret;
+}
+
+
+/**
+ * vb2_dqbuf() - Dequeue a buffer to the userspace
+ * @q: videobuf2 queue
+ * @b: buffer structure passed from userspace to vidioc_dqbuf handler
+ * in driver
+ * @nonblocking: if true, this call will not sleep waiting for a buffer if no
+ * buffers ready for dequeuing are present. Normally the driver
+ * would be passing (file->f_flags & O_NONBLOCK) here
+ *
+ * Should be called from vidioc_dqbuf ioctl handler of a driver.
+ * This function:
+ * 1) verifies the passed buffer,
+ * 2) calls buf_finish callback in the driver (if provided), in which
+ * driver can perform any additional operations that may be required before
+ * returning the buffer to userspace, such as cache sync,
+ * 3) the buffer struct members are filled with relevant information for
+ * the userspace.
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_dqbuf handler in driver.
+ */
+int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking)
+{
+ struct vb2_buffer *vb = NULL;
+ int ret;
+
+ mutex_lock(&q->vb_lock);
+
+ if (b->type != q->type) {
+ dprintk(1, "dqbuf: invalid buffer type\n");
+ ret = -EINVAL;
+ goto done;
+ }
+
+ ret = __vb2_get_done_vb(q, &vb, nonblocking);
+ if (ret < 0) {
+ dprintk(1, "dqbuf: error getting next done buffer\n");
+ goto done;
+ }
+
+ if (q->ops->buf_finish) {
+ ret = q->ops->buf_finish(vb);
+ if (ret) {
+ dprintk(1, "dqbuf: buffer finish failed\n");
+ goto done;
+ }
+ }
+
+ switch (vb->state) {
+ case VB2_BUF_STATE_DONE:
+ dprintk(3, "dqbuf: Returning done buffer\n");
+ break;
+ case VB2_BUF_STATE_ERROR:
+ dprintk(3, "dqbuf: Returning done buffer with errors\n");
+ break;
+ default:
+ dprintk(1, "dqbuf: Invalid buffer state\n");
+ ret = -EINVAL;
+ goto done;
+ }
+
+ /* Fill buffer information for the userspace */
+ __fill_v4l2_buffer(vb, b);
+ /* Remove from videobuf queue */
+ list_del(&vb->queued_entry);
+
+ dprintk(1, "dqbuf of buffer %d, with state %d\n",
+ vb->v4l2_buf.index, vb->state);
+
+ vb->state = VB2_BUF_STATE_DEQUEUED;
+
+done:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_dqbuf);
+
+/**
+ * vb2_streamon - start streaming
+ * @q: videobuf2 queue
+ * @type: type argument passed from userspace to vidioc_streamon handler
+ *
+ * Should be called from vidioc_streamon handler of a driver.
+ * This function:
+ * 1) verifies current state
+ * 2) starts streaming and passes any previously queued buffers to the driver
+ *
+ * The return values from this function are intended to be directly returned
+ * from vidioc_streamon handler in the driver.
+ */
+int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type)
+{
+ struct vb2_buffer *vb;
+ int ret = 0;
+
+ mutex_lock(&q->vb_lock);
+
+ if (type != q->type) {
+ dprintk(1, "streamon: invalid stream type\n");
+ ret = -EINVAL;
+ goto done;
+ }
+
+ if (q->streaming) {
+ dprintk(1, "streamon: already streaming\n");
+ ret = -EBUSY;
+ goto done;
+ }
+
+ /*
+ * Cannot start streaming on an OUTPUT device if no buffers have
+ * been queued yet.
+ */
+ if (V4L2_TYPE_IS_OUTPUT(q->type)) {
+ if (list_empty(&q->queued_list)) {
+ dprintk(1, "streamon: no output buffers queued\n");
+ ret = -EINVAL;
+ goto done;
+ }
+ }
+
+ q->streaming = 1;
+
+ /*
+ * If any buffers were queued before streamon,
+ * we can now pass them to driver for processing.
+ */
+ list_for_each_entry(vb, &q->queued_list, queued_entry)
+ __enqueue_in_driver(vb);
+
+ dprintk(3, "Streamon successful\n");
+done:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_streamon);
+
+/**
+ * __vb2_queue_cancel() - cancel and stop (pause) streaming
+ *
+ * Removes all queued buffers from driver's queue and all buffers queued by
+ * userspace from videobuf's queue. Returns to state after reqbufs.
+ */
+static void __vb2_queue_cancel(struct vb2_queue *q)
+{
+ unsigned long flags = 0;
+ int i;
+
+ q->streaming = 0;
+
+ /*
+ * Remove buffers from driver's queue. If a hardware operation
+ * is currently underway, drv_lock should be claimed and we will
+ * have to wait for it to finish before taking back buffers.
+ */
+ spin_lock_irqsave(q->drv_lock, flags);
+ for (i = 0; i < q->num_buffers; ++i) {
+ if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE)
+ list_del(&q->bufs[i]->drv_entry);
+ q->bufs[i]->state = VB2_BUF_STATE_DEQUEUED;
+ }
+ spin_unlock_irqrestore(q->drv_lock, flags);
+
+ /*
+ * Remove all buffers from videobuf's list...
+ */
+ INIT_LIST_HEAD(&q->queued_list);
+ /*
+ * ...and done list; userspace will not receive any buffers it
+ * has not already dequeued before initiating cancel.
+ */
+ INIT_LIST_HEAD(&q->done_list);
+ wake_up_interruptible_all(&q->done_wq);
+}
+
+/**
+ * vb2_streamoff - stop streaming
+ * @q: videobuf2 queue
+ * @type: type argument passed from userspace to vidioc_streamoff handler
+ *
+ * Should be called from vidioc_streamoff handler of a driver.
+ * This function:
+ * 1) verifies current state,
+ * 2) stop streaming and dequeues any queued buffers, including those previously
+ * passed to the driver (after waiting for the driver to finish).
+ *
+ * This call can be used for pausing playback.
+ * The return values from this function are intended to be directly returned
+ * from vidioc_streamoff handler in the driver
+ */
+int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type)
+{
+ int ret = 0;
+
+ mutex_lock(&q->vb_lock);
+
+ if (type != q->type) {
+ dprintk(1, "streamoff: invalid stream type\n");
+ ret = -EINVAL;
+ goto end;
+ }
+
+ if (!q->streaming) {
+ dprintk(1, "streamoff: not streaming\n");
+ ret = -EINVAL;
+ goto end;
+ }
+
+ /*
+ * Cancel will pause streaming and remove all buffers from the driver
+ * and videobuf, effectively returning control over them to userspace.
+ */
+ __vb2_queue_cancel(q);
+
+ dprintk(3, "Streamoff successful\n");
+end:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_streamoff);
+
+/**
+ * __find_plane_by_off() - find plane associated with the given offset off
+ */
+int __find_plane_by_off(struct vb2_queue *q, unsigned long off,
+ unsigned int *_buffer, unsigned int *_plane)
+{
+ struct vb2_buffer *vb;
+ unsigned int buffer, plane;
+
+ /*
+ * Go over all buffers and their planes, comparing the given offset
+ * with an offset assigned to each plane. If a match is found,
+ * return its buffer and plane numbers.
+ */
+ for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+ vb = q->bufs[buffer];
+
+ for (plane = 0; plane < vb->num_planes; ++plane) {
+ if (vb->v4l2_planes[plane].m.mem_offset == off) {
+ *_buffer = buffer;
+ *_plane = plane;
+ return 0;
+ }
+ }
+ }
+
+ return -EINVAL;
+}
+
+/**
+ * vb2_mmap() - map video buffers into application address space
+ * @q: videobuf2 queue
+ * @vma: vma passed to the mmap file operation handler in the driver
+ *
+ * Should be called from mmap file operation handler of a driver.
+ * This function maps one plane of one of the available video buffers to
+ * userspace. To map whole video memory allocated on reqbufs, this function
+ * has to be called once per each plane per each buffer previously allocated.
+ *
+ * When the userspace application calls mmap, it passes to it an offset returned
+ * to it earlier by the means of vidioc_querybuf handler. That offset acts as
+ * a "cookie", which is then used to identify the plane to be mapped.
+ * This function finds a plane with a matching offset and a mapping is performed
+ * by the means of a provided memory operation.
+ *
+ * The return values from this function are intended to be directly returned
+ * from the mmap handler in driver.
+ */
+int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma)
+{
+ unsigned long off = vma->vm_pgoff << PAGE_SHIFT;
+ struct vb2_plane *vb_plane;
+ struct vb2_buffer *vb;
+ unsigned int buffer, plane;
+ int ret = -EINVAL;
+
+ if (q->memory != V4L2_MEMORY_MMAP) {
+ dprintk(1, "Queue is not currently set up for mmap\n");
+ return ret;
+ }
+
+ if (!(vma->vm_flags & VM_WRITE) || !(vma->vm_flags & VM_SHARED)) {
+ dprintk(1, "Invalid vma flags (need VM_WRITE | VM_SHARED)\n");
+ return ret;
+ }
+
+ mutex_lock(&q->vb_lock);
+
+ /*
+ * Find the plane corresponding to the offset passed by userspace.
+ */
+ ret = __find_plane_by_off(q, off, &buffer, &plane);
+ if (ret)
+ goto end;
+
+ vb = q->bufs[buffer];
+ vb_plane = &vb->planes[plane];
+
+ if (vb_plane->mapped) {
+ dprintk(1, "Plane already mapped\n");
+ goto end;
+ }
+
+ if (!mem_ops(q, plane)->mmap) {
+ dprintk(1, "mmap not supported\n");
+ goto end;
+ }
+
+ ret = mem_ops(q, plane)->mmap(vb_plane->mem_priv, vma);
+ if (ret)
+ goto end;
+
+ vb_plane->mapped = 1;
+ vb->num_planes_mapped++;
+
+ dprintk(3, "Buffer %d, plane %d successfully mapped\n", buffer, plane);
+end:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_mmap);
+
+/**
+ * vb2_has_consumers() - return true if the userspace is waiting for a buffer
+ * @q: videobuf2 queue
+ *
+ * This function returns true if a userspace application is waiting for a buffer
+ * to be ready to dequeue (on which a hardware operation has been finished).
+ */
+bool vb2_has_consumers(struct vb2_queue *q)
+{
+ return waitqueue_active(&q->done_wq);
+}
+EXPORT_SYMBOL_GPL(vb2_has_consumers);
+
+/**
+ * vb2_poll() - implements poll userspace operation
+ * @q: videobuf2 queue
+ * @file: file argument passed to the poll file operation handler
+ * @wait: wait argument passed to the poll file operation handler
+ *
+ * This function implements poll file operation handler for a driver.
+ * For CAPTURE queues, if a buffer is ready to be dequeued, the userspace will
+ * be informed that the file descriptor of a video device is available for
+ * reading.
+ * For OUTPUT queues, if a buffer is ready to be dequeued, the file descriptor
+ * will be reported as available for writing.
+ *
+ * The return values from this function are intended to be directly returned
+ * from poll handler in driver.
+ */
+unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait)
+{
+ unsigned long flags = 0;
+ unsigned int ret = 0;
+ struct vb2_buffer *vb = NULL;
+
+ mutex_lock(&q->vb_lock);
+
+ /*
+ * There is nothing to wait for if no buffers have already been queued.
+ */
+ if (list_empty(&q->queued_list)) {
+ ret = POLLERR;
+ goto end;
+ }
+
+ poll_wait(file, &q->done_wq, wait);
+
+ /*
+ * Take first buffer available for dequeuing.
+ */
+ spin_lock_irqsave(&q->done_lock, flags);
+ if (!list_empty(&q->done_list))
+ vb = list_first_entry(&q->done_list, struct vb2_buffer,
+ done_entry);
+ spin_unlock_irqrestore(&q->done_lock, flags);
+
+ if (!vb)
+ goto end;
+
+ if (vb->state == VB2_BUF_STATE_DONE
+ || vb->state == VB2_BUF_STATE_ERROR) {
+ if (V4L2_TYPE_IS_OUTPUT(q->type))
+ ret = POLLOUT | POLLWRNORM;
+ else
+ ret = POLLIN | POLLRDNORM;
+ }
+end:
+ mutex_unlock(&q->vb_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(vb2_poll);
+
+/**
+ * vb2_queue_init() - initialize a videobuf2 queue
+ * @q: videobuf2 queue; this structure should be allocated in driver
+ * @ops: driver-specific callbacks
+ * @alloc_ctx: memory handler/allocator-specific context to be used;
+ * the given context will be used for memory allocation on all
+ * planes and buffers; it is possible to assign different contexts
+ * per plane, use vb2_set_alloc_ctx() for that
+ * @drv_lock: a lock for synchronization between the driver and videobuf,
+ * it should be locked by driver whenever an operation is being
+ * performed on a video buffer; this prevents videobuf from
+ * forcefully taking back a buffer from a driver in the middle
+ * of a hardware operation in case of an unexpected application
+ * close or queue cancellation
+ * @type: queue type
+ * @drv_priv: driver private data, may be NULL; it can be used by driver in
+ * driver-specific callbacks when issued
+ */
+int vb2_queue_init(struct vb2_queue *q, const struct vb2_ops *ops,
+ const struct vb2_alloc_ctx *alloc_ctx,
+ spinlock_t *drv_lock, enum v4l2_buf_type type,
+ void *drv_priv)
+{
+ unsigned int i;
+
+ BUG_ON(!q);
+ BUG_ON(!ops);
+ BUG_ON(!ops->queue_negotiate);
+ BUG_ON(!ops->plane_setup);
+ BUG_ON(!ops->buf_queue);
+
+ BUG_ON(!alloc_ctx);
+ BUG_ON(!alloc_ctx->mem_ops);
+
+ memset(q, 0, sizeof *q);
+ q->ops = ops;
+
+ for (i = 0; i < VIDEO_MAX_PLANES; ++i)
+ q->alloc_ctx[i] = alloc_ctx;
+
+ q->drv_lock = drv_lock;
+ q->type = type;
+ q->drv_priv = drv_priv;
+
+ mutex_init(&q->vb_lock);
+ INIT_LIST_HEAD(&q->queued_list);
+ INIT_LIST_HEAD(&q->done_list);
+ spin_lock_init(&q->done_lock);
+ init_waitqueue_head(&q->done_wq);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(vb2_queue_init);
+
+/**
+ * vb2_queue_release() - stop streaming, release the queue and free memory
+ * @q: videobuf2 queue
+ *
+ * This function stops streaming and performs necessary clean ups, including
+ * freeing video buffer memory. The driver is responsible for freeing
+ * the vb2_queue structure itself.
+ */
+void vb2_queue_release(struct vb2_queue *q)
+{
+ mutex_lock(&q->vb_lock);
+
+ __vb2_queue_cancel(q);
+ __vb2_queue_free(q);
+
+ mutex_unlock(&q->vb_lock);
+}
+EXPORT_SYMBOL_GPL(vb2_queue_release);
+
+MODULE_DESCRIPTION("Driver helper framework for Video for Linux 2");
+MODULE_AUTHOR("Pawel Osciak");
+MODULE_LICENSE("GPL");
new file mode 100644
@@ -0,0 +1,337 @@
+/*
+ * videobuf2-core.h - V4L2 driver helper framework
+ *
+ * Copyright (C) 2010 Samsung Electronics
+ *
+ * Author: Pawel Osciak <p.osciak@samsung.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+#ifndef _MEDIA_VIDEOBUF2_CORE_H
+#define _MEDIA_VIDEOBUF2_CORE_H
+
+#include <linux/mutex.h>
+#include <linux/mm_types.h>
+#include <linux/videodev2.h>
+#include <linux/poll.h>
+
+/**
+ * enum vb2_buffer_state - current video buffer state
+ * @VB2_BUF_STATE_DEQUEUED: buffer under userspace control
+ * @VB2_BUF_STATE_QUEUED: buffer queued in videobuf, but not in driver
+ * @VB2_BUF_STATE_ACTIVE: buffer queued in driver and possibly used
+ * in a hardware operation
+ * @VB2_BUF_STATE_DONE: buffer returned from driver to videobuf, but
+ * not yet dequeued to userspace
+ * @VB2_BUF_STATE_ERROR: same as above, but the operation on the buffer
+ * has ended with an error, which will be reported
+ * to the userspace when it is dequeued
+ */
+enum vb2_buffer_state {
+ VB2_BUF_STATE_DEQUEUED,
+ VB2_BUF_STATE_QUEUED,
+ VB2_BUF_STATE_ACTIVE,
+ VB2_BUF_STATE_DONE,
+ VB2_BUF_STATE_ERROR,
+};
+
+/**
+ * struct vb2_plane - private videobuf per-plane info
+ * @mem_priv: allocator-specific, per-memory buffer private structure
+ * @mapped: set if the plane is mapped
+ */
+struct vb2_plane {
+ void *mem_priv;
+ int mapped:1;
+};
+
+/**
+ * struct vb2_buffer - represents a video buffer
+ * @v4l2_buf: struct v4l2_buffer associated with this buffer; can
+ * be read by the driver and relevant entries can be
+ * changed by the driver in case of CAPTURE types
+ * (such as timestamp)
+ * @v4l2_planes: struct v4l2_planes associated with this buffer; can
+ * be read by the driver and relevant entries can be
+ * changed by the driver in case of CAPTURE types
+ * (such as bytesused); NOTE that even for single-planar
+ * types, the v4l2_planes[0] struct should be used
+ * instead of v4l2_buf for filling bytesused - drivers
+ * should use the vb2_set_plane_payload() function for that
+ * @vb2_queue: the queue to which this driver belongs
+ * @drv_entry: list entry to be used by driver for storing the buffer
+ * @num_planes: number of planes in the buffer
+ * on an internal driver queue
+ * @state: current buffer state; do not change
+ * @queued_entry: entry on the queued buffers list, which holds all
+ * buffers queued from userspace
+ * @done_entry: entry on the list that stores all buffers ready to
+ * be dequeued to userspace
+ * @planes: private per-plane information; do not change
+ * @num_planes_mapped: number of mapped planes; do not change
+ */
+struct vb2_buffer {
+ struct v4l2_buffer v4l2_buf;
+ struct v4l2_plane v4l2_planes[VIDEO_MAX_PLANES];
+
+ struct vb2_queue *vb2_queue;
+
+ struct list_head drv_entry;
+ unsigned int num_planes;
+
+/* Private: internal use only */
+ enum vb2_buffer_state state;
+
+ struct list_head queued_entry;
+ struct list_head done_entry;
+
+ struct vb2_plane planes[VIDEO_MAX_PLANES];
+ unsigned int num_planes_mapped;
+};
+
+/**
+ * struct vb2_ops - driver-specific callbacks
+ * @queue_negotiate: called from a VIDIOC_REQBUFS handler, before
+ * memory allocation; driver should return the required
+ * number of buffers in num_buffers and the required number
+ * of planes per buffer in num_planes
+ * @plane_setup: called before memory allocation num_planes times;
+ * driver should return the required size of plane number
+ * plane_no
+ * @buf_queue: passes buffer vb to the driver; driver may use the
+ * vb->drv_entry member to store the buffer on its internal
+ * queue and start hardware operation on this buffer;
+ * @buf_init: called once after allocating a buffer (in MMAP case)
+ * or after acquiring a new USERPTR buffer; drivers may
+ * perform additional buffer-related initialization;
+ * initialization failure (return != 0) will prevent
+ * queue setup from completing successfully; optional
+ * @buf_prepare: called every time the buffer is queued from userspace;
+ * drivers may perform any initialization required before
+ * each hardware operation in this callback;
+ * if an error is returned, the buffer will not be queued
+ * in driver; optional
+ * @buf_finish: called before every dequeue of the buffer back to
+ * userspace; drivers may perform any operations required
+ * before userspace accesses the buffer; optional
+ * @buf_cleanup: called once before the buffer is freed; drivers may
+ * perform any additional cleanup; optional
+ */
+struct vb2_ops {
+ int (*queue_negotiate)(struct vb2_queue *q, unsigned int *num_buffers,
+ unsigned int *num_planes);
+ int (*plane_setup)(struct vb2_queue *q,
+ unsigned int plane_no, unsigned long *plane_size);
+ void (*buf_queue)(struct vb2_buffer *vb);
+
+ int (*buf_init)(struct vb2_buffer *vb);
+ int (*buf_prepare)(struct vb2_buffer *vb);
+ int (*buf_finish)(struct vb2_buffer *vb);
+ void (*buf_cleanup)(struct vb2_buffer *vb);
+};
+
+/**
+ * struct vb2_queue - a videobuf queue
+ *
+ * @type: current queue type
+ * @memory: current memory type used
+ * @drv_priv: driver private data, passed on vb2_queue_init
+ * @bufs: videobuf buffer structures
+ * @num_buffers: number of allocated/used buffers
+ * @vb_lock: for ioctl handler and queue state changes synchronization
+ * @queued_list: list of buffers currently queued from userspace
+ * @done_list: list of buffers ready to be dequeued to userspace
+ * @done_lock: lock to protect done_list list
+ * @done_wq: waitqueue for processes waiting for buffers ready to be dequeued
+ * @drv_lock: driver lock for synchronization between driver and videobuf,
+ * passed on vb2_queue_init
+ * @ops: driver-specific callbacks
+ * @alloc_ctx: memory type/allocator-specific callbacks
+ * @streaming: current streaming state
+ * @userptr_supported: true if queue supports USERPTR types
+ * @mmap_supported: true if queue supports MMAP types
+ */
+struct vb2_queue {
+ enum v4l2_buf_type type;
+ enum v4l2_memory memory;
+ void *drv_priv;
+
+/* private: internal use only */
+ struct vb2_buffer *bufs[VIDEO_MAX_FRAME];
+ unsigned int num_buffers;
+
+ struct mutex vb_lock;
+ struct list_head queued_list;
+
+ struct list_head done_list;
+ spinlock_t done_lock;
+ wait_queue_head_t done_wq;
+
+ spinlock_t *drv_lock;
+
+ const struct vb2_ops *ops;
+ const struct vb2_alloc_ctx *alloc_ctx[VIDEO_MAX_PLANES];
+
+ int streaming:1;
+ int userptr_supported:1;
+ int mmap_supported:1;
+};
+
+/* The below functions are documented in videobuf2-core.c */
+void *vb2_plane_vaddr(struct vb2_buffer *vb, unsigned int plane_no);
+unsigned long vb2_plane_paddr(struct vb2_buffer *vb, unsigned int plane_no);
+void vb2_buffer_done(struct vb2_buffer *vb, enum vb2_buffer_state state);
+bool vb2_has_consumers(struct vb2_queue *q);
+
+int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b);
+int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req);
+
+int vb2_queue_init(struct vb2_queue *q, const struct vb2_ops *ops,
+ const struct vb2_alloc_ctx *alloc_ctx,
+ spinlock_t *drv_lock, enum v4l2_buf_type type,
+ void *drv_priv);
+void vb2_queue_release(struct vb2_queue *q);
+
+int vb2_qbuf(struct vb2_queue *q, struct v4l2_buffer *b);
+int vb2_dqbuf(struct vb2_queue *q, struct v4l2_buffer *b, bool nonblocking);
+
+int vb2_streamon(struct vb2_queue *q, enum v4l2_buf_type type);
+int vb2_streamoff(struct vb2_queue *q, enum v4l2_buf_type type);
+
+int vb2_mmap(struct vb2_queue *q, struct vm_area_struct *vma);
+unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait);
+
+/**
+ * vb2_get_drv_priv() - return driver private data associated with the queue
+ * @q: videobuf queue
+ */
+static inline void *vb2_get_drv_priv(struct vb2_queue *q)
+{
+ return q->drv_priv;
+}
+
+/**
+ * vb2_set_plane_payload() - set bytesused for the plane plane_no
+ * @vb: buffer for which plane payload should be set
+ * @plane_no: plane number for which payload should be set
+ * @size: payload in bytes
+ */
+static inline void vb2_set_plane_payload(struct vb2_buffer *vb,
+ unsigned int plane_no, unsigned long size)
+{
+ if (!V4L2_TYPE_IS_MULTIPLANAR(vb->vb2_queue->type) && plane_no == 0)
+ vb->v4l2_buf.bytesused = size;
+ else
+ vb->v4l2_planes[plane_no].bytesused = size;
+}
+
+/**
+ * vb2_plane_size() - return plane size in bytes
+ * @vb: buffer for which plane size should be returned
+ * @plane_no: plane number for which size should be returned
+ */
+static inline unsigned long
+vb2_plane_size(struct vb2_buffer *vb, unsigned int plane_no)
+{
+ if (plane_no < vb->num_planes)
+ return vb->v4l2_planes[plane_no].length;
+ else
+ return 0;
+}
+
+/**
+ * vb2_set_alloc_ctx() - use to assign a allocator context for a plane
+ * @q: videobuf queue
+ * @alloc_ctx: allocator context to be assigned
+ * @plane_no: plane number to which the context is to be assigned
+ *
+ * This function can be used to assign additional allocator contexts
+ * on a per-plane basis, if a driver requires such feature.
+ * When a driver passes an allocator context to the vb2_queue_init call,
+ * it is initially assigned to all planes. Driver can then use this call
+ * to selectively assign additional contexts to particular planes.
+ * A context assigned to plane_no will be used for memory operations
+ * on plane number plane_no for all buffers.
+ */
+static inline void
+vb2_set_alloc_ctx(struct vb2_queue *q, struct vb2_alloc_ctx *alloc_ctx,
+ unsigned int plane_no)
+{
+ if (plane_no < VIDEO_MAX_PLANES)
+ q->alloc_ctx[plane_no] = alloc_ctx;
+}
+struct vb2_mem_ops;
+
+/**
+ * struct vb2_alloc_ctx - allocator/memory handler-specific context
+ * @mem_ops: memory operations used by the current context
+ *
+ * This structure is passed to the alloc() call and can be used to store
+ * additional allocator private data. In such case it can be embedded in
+ * a allocator private structure as its first member.
+ * In more complicated cases, separate contexts can be assigned to each plane,
+ * if required. This would allow separate memory allocation/handling strategies
+ * for each plane, which is useful for drivers requiring different memory types
+ * and/or handling for each plane.
+ *
+ * See videobuf2-vmalloc.c and videobuf2-dma-coherent.c for example usage.
+ */
+struct vb2_alloc_ctx {
+ const struct vb2_mem_ops *mem_ops;
+};
+
+/**
+ * struct vb2_mem_ops - memory handling/memory allocator operations
+ * @alloc: allocate video memory and, optionally, allocator private data,
+ * return NULL on failure or a pointer to allocator private,
+ * per-buffer data on success, NULL on failure; the returned
+ * private structure will then be passed as buf_priv argument
+ * to other ops in this structure
+ * @put: inform the allocator that the buffer will no longer be used;
+ * usually will result in the allocator freeing the buffer (if
+ * no other users of this buffer are present); the buf_priv
+ * argument is the allocator private per-buffer structure
+ * previously returned from the alloc callback
+ * @get_userptr: acquire userspace memory for a hardware operation; used for
+ * USERPTR memory types; vaddr is the address passed to the
+ * videobuf layer when queuing a video buffer of USERPTR type;
+ * should return an allocator private per-buffer structure
+ * associated with the buffer on success, NULL on failure;
+ * the returned private structure will then be passed as buf_priv
+ * argument to other ops in this structure
+ * @put_userptr: inform the allocator that a USERPTR buffer will no longer
+ * be used
+ * @vaddr: return a kernel virtual address to a given memory buffer
+ * associated with the passed private structure or NULL if no
+ * such mapping exists
+ * @paddr: return a physical address to a given memory buffer associated
+ * with the passed private structure or NULL if not available
+ * @num_users: return the current number of users of a memory buffer;
+ * return 1 if the videobuf layer (or actually the driver using
+ * it) is the only user
+ * @mmap: setup a userspace mapping for a given memory buffer under
+ * the provided virtual memory region
+ *
+ * Required ops for USERPTR types: get_userptr, put_userptr.
+ * Required ops for MMAP types: alloc, put, num_users, mmap.
+ */
+struct vb2_mem_ops {
+ void *(*alloc)(const struct vb2_alloc_ctx *alloc_ctx,
+ unsigned long size);
+ void (*put)(void *buf_priv);
+
+ void *(*get_userptr)(unsigned long vaddr,
+ unsigned long size);
+ void (*put_userptr)(void *buf_priv);
+
+ void *(*vaddr)(void *buf_priv);
+ unsigned long (*paddr)(void *buf_priv);
+ unsigned int (*num_users)(void *buf_priv);
+
+ int (*mmap)(void *buf_priv, struct vm_area_struct *vma);
+};
+
+
+#endif /* _MEDIA_VIDEOBUF2_CORE_H */