[v5,4/4] media: videobuf2-core: attach once if multiple planes share the same dbuf
Commit Message
When multiple planes use the same dma buf, each plane will have its own dma
buf attachment and mapping. It is a waste of IOVA space.
This patch adds a dbuf_duplicated boolean in vb2_plane. If a plane's dbuf
is the same as an existing plane, do not create another attachment and
mapping.
Signed-off-by: Yunke Cao <yunkec@chromium.org>
Acked-by: Tomasz Figa <tfiga@chromium.org>
---
v5
- Fix typo in videobuf2-core.h comments.
v4
- Only set dbuf_duplicated when alloc_devs are equal.
v3
- Adjust the patch according to the previous patches to resolve conflicts.
- Add comment to explain the purpose of the change.
v2
- Separate out the refactor changes out to previous patches.
- Fix mem_priv check.
.../media/common/videobuf2/videobuf2-core.c | 30 ++++++++++++++++---
include/media/videobuf2-core.h | 3 ++
2 files changed, 29 insertions(+), 4 deletions(-)
@@ -303,10 +303,13 @@ static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb, struct vb2_plane *p)
if (!p->mem_priv)
return;
- if (p->dbuf_mapped)
- call_void_memop(vb, unmap_dmabuf, p->mem_priv);
+ if (!p->dbuf_duplicated) {
+ if (p->dbuf_mapped)
+ call_void_memop(vb, unmap_dmabuf, p->mem_priv);
+
+ call_void_memop(vb, detach_dmabuf, p->mem_priv);
+ }
- call_void_memop(vb, detach_dmabuf, p->mem_priv);
dma_buf_put(p->dbuf);
p->mem_priv = NULL;
p->dbuf = NULL;
@@ -315,6 +318,7 @@ static void __vb2_plane_dmabuf_put(struct vb2_buffer *vb, struct vb2_plane *p)
p->length = 0;
p->m.fd = 0;
p->data_offset = 0;
+ p->dbuf_duplicated = false;
}
/*
@@ -1379,7 +1383,7 @@ static int __prepare_dmabuf(struct vb2_buffer *vb)
struct vb2_plane planes[VB2_MAX_PLANES];
struct vb2_queue *q = vb->vb2_queue;
void *mem_priv;
- unsigned int plane;
+ unsigned int plane, i;
int ret = 0;
bool reacquired = vb->planes[0].mem_priv == NULL;
@@ -1432,6 +1436,24 @@ static int __prepare_dmabuf(struct vb2_buffer *vb)
}
for (plane = 0; plane < vb->num_planes; ++plane) {
+ /*
+ * This is an optimization to reduce dma_buf attachment/mapping.
+ * When the same dma_buf is used for multiple planes, there is no need
+ * to create duplicated attachments.
+ */
+ for (i = 0; i < plane; ++i) {
+ if (planes[plane].dbuf == vb->planes[i].dbuf &&
+ q->alloc_devs[plane] == q->alloc_devs[i]) {
+ vb->planes[plane].dbuf_duplicated = true;
+ vb->planes[plane].dbuf = vb->planes[i].dbuf;
+ vb->planes[plane].mem_priv = vb->planes[i].mem_priv;
+ break;
+ }
+ }
+
+ if (vb->planes[plane].dbuf_duplicated)
+ continue;
+
/* Acquire each plane's memory */
mem_priv = call_ptr_memop(attach_dmabuf,
vb,
@@ -154,6 +154,8 @@ struct vb2_mem_ops {
* @mem_priv: private data with this plane.
* @dbuf: dma_buf - shared buffer object.
* @dbuf_mapped: flag to show whether dbuf is mapped or not
+ * @dbuf_duplicated: boolean to show whether dbuf is duplicated with a
+ * previous plane of the buffer.
* @bytesused: number of bytes occupied by data in the plane (payload).
* @length: size of this plane (NOT the payload) in bytes. The maximum
* valid size is MAX_UINT - PAGE_SIZE.
@@ -179,6 +181,7 @@ struct vb2_plane {
void *mem_priv;
struct dma_buf *dbuf;
unsigned int dbuf_mapped;
+ bool dbuf_duplicated;
unsigned int bytesused;
unsigned int length;
unsigned int min_length;