On 12/17/19 4:20 AM, Sergey Senozhatsky wrote:
> Set video buffer cache management flags corresponding to V4L2 cache
> flags.
>
> Both ->prepare() and ->finish() cache management hints should be
> passed during this stage (buffer preparation), because there is no
> other way for user-space to skip ->finish() cache flush.
>
> There are two possible alternative approaches:
> - The first one is to move cache sync from ->finish() to dqbuf().
> But this breaks some drivers, that need to fix-up buffers before
> dequeueing them.
>
> - The second one is to move ->finish() call from ->done() to dqbuf.
Please combine this patch with patch 13/15!
>
> Signed-off-by: Sergey Senozhatsky <[email protected]>
> ---
> .../media/common/videobuf2/videobuf2-v4l2.c | 22 +++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index e652f4318284..2fccfe2a57f8 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -337,6 +337,27 @@ static int vb2_fill_vb2_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b
> return 0;
> }
>
> +static void set_buffer_cache_hints(struct vb2_queue *q,
> + struct vb2_buffer *vb,
> + struct v4l2_buffer *b)
> +{
> + vb->need_cache_sync_on_prepare = 1;
> +
> + if (q->dma_dir != DMA_TO_DEVICE)
What should be done when dma_dir == DMA_BIDIRECTIONAL?
> + vb->need_cache_sync_on_finish = 1;
> + else
> + vb->need_cache_sync_on_finish = 0;
> +
> + if (!q->allow_cache_hints)
> + return;
> +
> + if (b->flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE)
> + vb->need_cache_sync_on_finish = 0;
> +
> + if (b->flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN)
> + vb->need_cache_sync_on_prepare = 0;
> +}
> +
> static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
> struct v4l2_buffer *b, bool is_prepare,
> struct media_request **p_req)
> @@ -381,6 +402,7 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
> }
>
> if (!vb->prepared) {
> + set_buffer_cache_hints(q, vb, b);
> /* Copy relevant information provided by the userspace */
> memset(vbuf->planes, 0,
> sizeof(vbuf->planes[0]) * vb->num_planes);
>
Regards,
Hans
Hi,
Sorry for the delayed.
On (20/01/10 11:24), Hans Verkuil wrote:
> On 12/17/19 4:20 AM, Sergey Senozhatsky wrote:
> > Set video buffer cache management flags corresponding to V4L2 cache
> > flags.
> >
> > Both ->prepare() and ->finish() cache management hints should be
> > passed during this stage (buffer preparation), because there is no
> > other way for user-space to skip ->finish() cache flush.
> >
> > There are two possible alternative approaches:
> > - The first one is to move cache sync from ->finish() to dqbuf().
> > But this breaks some drivers, that need to fix-up buffers before
> > dequeueing them.
> >
> > - The second one is to move ->finish() call from ->done() to dqbuf.
>
> Please combine this patch with patch 13/15!
OK.
[..]
> > }
> >
> > +static void set_buffer_cache_hints(struct vb2_queue *q,
> > + struct vb2_buffer *vb,
> > + struct v4l2_buffer *b)
> > +{
> > + vb->need_cache_sync_on_prepare = 1;
> > +
> > + if (q->dma_dir != DMA_TO_DEVICE)
>
> What should be done when dma_dir == DMA_BIDIRECTIONAL?
Well, ->need_cache_sync_on_prepare/->need_cache_sync_on_finish are set,
by default. If the queue supports user-space cache hints (driver has
set ->allow_cache_hints), then user-space can override cache behavior.
We probably cannot enforce any other behavior here. Am I missing
something?
> > + vb->need_cache_sync_on_finish = 1;
> > + else
> > + vb->need_cache_sync_on_finish = 0;
> > +
> > + if (!q->allow_cache_hints)
> > + return;
> > +
> > + if (b->flags & V4L2_BUF_FLAG_NO_CACHE_INVALIDATE)
> > + vb->need_cache_sync_on_finish = 0;
> > +
> > + if (b->flags & V4L2_BUF_FLAG_NO_CACHE_CLEAN)
> > + vb->need_cache_sync_on_prepare = 0;
> > +}
-ss
On (20/01/22 10:39), Sergey Senozhatsky wrote:
> [..]
> > > }
> > >
> > > +static void set_buffer_cache_hints(struct vb2_queue *q,
> > > + struct vb2_buffer *vb,
> > > + struct v4l2_buffer *b)
> > > +{
> > > + vb->need_cache_sync_on_prepare = 1;
> > > +
> > > + if (q->dma_dir != DMA_TO_DEVICE)
> >
> > What should be done when dma_dir == DMA_BIDIRECTIONAL?
>
[..]
> We probably cannot enforce any other behavior here. Am I missing
> something?
Never mind. I got your point.
-ss
On Wed, Jan 22, 2020 at 11:53 AM Sergey Senozhatsky
<[email protected]> wrote:
>
> On (20/01/22 10:39), Sergey Senozhatsky wrote:
> > [..]
> > > > }
> > > >
> > > > +static void set_buffer_cache_hints(struct vb2_queue *q,
> > > > + struct vb2_buffer *vb,
> > > > + struct v4l2_buffer *b)
> > > > +{
> > > > + vb->need_cache_sync_on_prepare = 1;
> > > > +
> > > > + if (q->dma_dir != DMA_TO_DEVICE)
> > >
> > > What should be done when dma_dir == DMA_BIDIRECTIONAL?
> >
>
> [..]
>
> > We probably cannot enforce any other behavior here. Am I missing
> > something?
>
> Never mind. I got your point.
DMA_BIDIRECTIONAL by default needs sync on both prepare and finish.
need_cache_sync_on_prepare is initialized to 1. Since
DMA_BIDIRECTIONAL != DMA_TO_DEVICE, need_cache_sync_on_finish would
also be set to 1. Is anything still missing?