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