diff mbox series

[PATCHv4,10/11] videobuf2: add begin/end cpu_access callbacks to dma-sg

Message ID 20200302041213.27662-11-senozhatsky@chromium.org (mailing list archive)
State Changes Requested, archived
Delegated to: Hans Verkuil
Headers
Series Implement V4L2_BUF_FLAG_NO_CACHE_* flags |

Commit Message

Sergey Senozhatsky March 2, 2020, 4:12 a.m. UTC 
  Provide begin_cpu_access() and end_cpu_access() dma_buf_ops
callbacks for cache synchronisation on exported buffers.

V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
dma-sg allocates memory using the page allocator directly, so
there is no memory consistency guarantee.

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 .../media/common/videobuf2/videobuf2-dma-sg.c | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)

Comments

Hans Verkuil March 6, 2020, 2:04 p.m. UTC | #1 
On 02/03/2020 05:12, Sergey Senozhatsky wrote:
> Provide begin_cpu_access() and end_cpu_access() dma_buf_ops
> callbacks for cache synchronisation on exported buffers.
> 
> V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
> dma-sg allocates memory using the page allocator directly, so
> there is no memory consistency guarantee.
> 
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> ---
>  .../media/common/videobuf2/videobuf2-dma-sg.c | 28 +++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> index 6db60e9d5183..ddc67c9aaedb 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
> @@ -120,6 +120,12 @@ static void *vb2_dma_sg_alloc(struct device *dev, unsigned long dma_attrs,
>  	buf->num_pages = size >> PAGE_SHIFT;
>  	buf->dma_sgt = &buf->sg_table;
>  
> +	/*
> +	 * NOTE: dma-sg allocates memory using the page allocator directly, so
> +	 * there is no memory consistency guarantee, hence dma-sg ignores DMA
> +	 * attributes passed from the upper layer. That means that
> +	 * V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
> +	 */
>  	buf->pages = kvmalloc_array(buf->num_pages, sizeof(struct page *),
>  				    GFP_KERNEL | __GFP_ZERO);
>  	if (!buf->pages)
> @@ -470,6 +476,26 @@ static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
>  	vb2_dma_sg_put(dbuf->priv);
>  }
>  
> +static int vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
> +					enum dma_data_direction direction)

I suggest you use this style to avoid checkpatch warnings:

static int
vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
				       enum dma_data_direction direction)

> +{
> +	struct vb2_dma_sg_buf *buf = dbuf->priv;
> +	struct sg_table *sgt = buf->dma_sgt;
> +
> +	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> +	return 0;
> +}
> +
> +static int vb2_dma_sg_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
> +					enum dma_data_direction direction)

Ditto.

Regards,

	Hans

> +{
> +	struct vb2_dma_sg_buf *buf = dbuf->priv;
> +	struct sg_table *sgt = buf->dma_sgt;
> +
> +	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
> +	return 0;
> +}
> +
>  static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
>  {
>  	struct vb2_dma_sg_buf *buf = dbuf->priv;
> @@ -488,6 +514,8 @@ static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
>  	.detach = vb2_dma_sg_dmabuf_ops_detach,
>  	.map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
>  	.unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
> +	.begin_cpu_access = vb2_dma_sg_dmabuf_ops_begin_cpu_access,
> +	.end_cpu_access = vb2_dma_sg_dmabuf_ops_end_cpu_access,
>  	.vmap = vb2_dma_sg_dmabuf_ops_vmap,
>  	.mmap = vb2_dma_sg_dmabuf_ops_mmap,
>  	.release = vb2_dma_sg_dmabuf_ops_release,
>
Sergey Senozhatsky March 7, 2020, 5:26 a.m. UTC | #2 
On (20/03/06 15:04), Hans Verkuil wrote:
[..]
> > +	/*
> > +	 * NOTE: dma-sg allocates memory using the page allocator directly, so
> > +	 * there is no memory consistency guarantee, hence dma-sg ignores DMA
> > +	 * attributes passed from the upper layer. That means that
> > +	 * V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
> > +	 */
> >  	buf->pages = kvmalloc_array(buf->num_pages, sizeof(struct page *),
> >  				    GFP_KERNEL | __GFP_ZERO);
> >  	if (!buf->pages)
> > @@ -470,6 +476,26 @@ static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
> >  	vb2_dma_sg_put(dbuf->priv);
> >  }
> >  
> > +static int vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
> > +					enum dma_data_direction direction)
> 
> I suggest you use this style to avoid checkpatch warnings:
> 
> static int
> vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
> 				       enum dma_data_direction direction)

OK, will do.

Just for information, my checkpatch doesn't warn me:

$ ./scripts/checkpatch.pl outgoing/0010-videobuf2-add-begin-end-cpu_access-callbacks-to-dma-.patch
total: 0 errors, 0 warnings, 46 lines checked

outgoing/0010-videobuf2-add-begin-end-cpu_access-callbacks-to-dma-.patch has no obvious style problems and is ready for submission.

	-ss
Hans Verkuil March 7, 2020, 9:32 a.m. UTC | #3 
On 07/03/2020 06:26, Sergey Senozhatsky wrote:
> On (20/03/06 15:04), Hans Verkuil wrote:
> [..]
>>> +	/*
>>> +	 * NOTE: dma-sg allocates memory using the page allocator directly, so
>>> +	 * there is no memory consistency guarantee, hence dma-sg ignores DMA
>>> +	 * attributes passed from the upper layer. That means that
>>> +	 * V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
>>> +	 */
>>>  	buf->pages = kvmalloc_array(buf->num_pages, sizeof(struct page *),
>>>  				    GFP_KERNEL | __GFP_ZERO);
>>>  	if (!buf->pages)
>>> @@ -470,6 +476,26 @@ static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
>>>  	vb2_dma_sg_put(dbuf->priv);
>>>  }
>>>  
>>> +static int vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
>>> +					enum dma_data_direction direction)
>>
>> I suggest you use this style to avoid checkpatch warnings:
>>
>> static int
>> vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
>> 				       enum dma_data_direction direction)
> 
> OK, will do.
> 
> Just for information, my checkpatch doesn't warn me:
> 
> $ ./scripts/checkpatch.pl outgoing/0010-videobuf2-add-begin-end-cpu_access-callbacks-to-dma-.patch

We use the --strict option to checkpatch.

Regards,

	Hans

> total: 0 errors, 0 warnings, 46 lines checked
> 
> outgoing/0010-videobuf2-add-begin-end-cpu_access-callbacks-to-dma-.patch has no obvious style problems and is ready for submission.
> 
> 	-ss
>
Sergey Senozhatsky March 7, 2020, 9:39 a.m. UTC | #4 
On (20/03/07 10:32), Hans Verkuil wrote:
> >>> +static int vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
> >>> +					enum dma_data_direction direction)
> >>
> >> I suggest you use this style to avoid checkpatch warnings:
> >>
> >> static int
> >> vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
> >> 				       enum dma_data_direction direction)
> > 
> > OK, will do.
> > 
> > Just for information, my checkpatch doesn't warn me:
> > 
> > $ ./scripts/checkpatch.pl outgoing/0010-videobuf2-add-begin-end-cpu_access-callbacks-to-dma-.patch
> 
> We use the --strict option to checkpatch.

Got it.

	-ss
diff mbox series

Patch

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
index 6db60e9d5183..ddc67c9aaedb 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c
@@ -120,6 +120,12 @@  static void *vb2_dma_sg_alloc(struct device *dev, unsigned long dma_attrs,
 	buf->num_pages = size >> PAGE_SHIFT;
 	buf->dma_sgt = &buf->sg_table;
 
+	/*
+	 * NOTE: dma-sg allocates memory using the page allocator directly, so
+	 * there is no memory consistency guarantee, hence dma-sg ignores DMA
+	 * attributes passed from the upper layer. That means that
+	 * V4L2_FLAG_MEMORY_NON_CONSISTENT has no effect on dma-sg buffers.
+	 */
 	buf->pages = kvmalloc_array(buf->num_pages, sizeof(struct page *),
 				    GFP_KERNEL | __GFP_ZERO);
 	if (!buf->pages)
@@ -470,6 +476,26 @@  static void vb2_dma_sg_dmabuf_ops_release(struct dma_buf *dbuf)
 	vb2_dma_sg_put(dbuf->priv);
 }
 
+static int vb2_dma_sg_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
+					enum dma_data_direction direction)
+{
+	struct vb2_dma_sg_buf *buf = dbuf->priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+	return 0;
+}
+
+static int vb2_dma_sg_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
+					enum dma_data_direction direction)
+{
+	struct vb2_dma_sg_buf *buf = dbuf->priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
+	return 0;
+}
+
 static void *vb2_dma_sg_dmabuf_ops_vmap(struct dma_buf *dbuf)
 {
 	struct vb2_dma_sg_buf *buf = dbuf->priv;
@@ -488,6 +514,8 @@  static const struct dma_buf_ops vb2_dma_sg_dmabuf_ops = {
 	.detach = vb2_dma_sg_dmabuf_ops_detach,
 	.map_dma_buf = vb2_dma_sg_dmabuf_ops_map,
 	.unmap_dma_buf = vb2_dma_sg_dmabuf_ops_unmap,
+	.begin_cpu_access = vb2_dma_sg_dmabuf_ops_begin_cpu_access,
+	.end_cpu_access = vb2_dma_sg_dmabuf_ops_end_cpu_access,
 	.vmap = vb2_dma_sg_dmabuf_ops_vmap,
 	.mmap = vb2_dma_sg_dmabuf_ops_mmap,
 	.release = vb2_dma_sg_dmabuf_ops_release,