Re: [PATCH v17 8/8] media: verisilicon: Support deleting buffers on capture queue

[Benjamin Gaignard]

Le 24/01/2024 à 13:52, Hans Verkuil a écrit :
> On 19/01/2024 10:49, Benjamin Gaignard wrote:
> > Allow to delete buffers on capture queue because it the one which
> > own the decoded buffers. After a dynamic resolution change lot of
> > them could remain allocated but won't be used anymore so deleting
> > them save memory.
> > Do not add this feature on output queue because the buffers are
> > smaller, fewer and always recycled even after a dynamic resolution
> > change.
> >
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > ---
> >   drivers/media/platform/verisilicon/hantro_drv.c  | 1 +
> >   drivers/media/platform/verisilicon/hantro_v4l2.c | 1 +
> >   2 files changed, 2 insertions(+)
> >
> > diff --git a/drivers/media/platform/verisilicon/hantro_drv.c b/drivers/media/platform/verisilicon/hantro_drv.c
> > index db3df6cc4513..f6b0a676a740 100644
> > --- a/drivers/media/platform/verisilicon/hantro_drv.c
> > +++ b/drivers/media/platform/verisilicon/hantro_drv.c
> > @@ -248,6 +248,7 @@ queue_init(void *priv, struct vb2_queue *src_vq, struct vb2_queue *dst_vq)
> >   	dst_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> >   	dst_vq->lock = &ctx->dev->vpu_mutex;
> >   	dst_vq->dev = ctx->dev->v4l2_dev.dev;
> > +	src_vq->supports_delete_bufs = true;
> As I mentioned, I remain unconvinced by this. It is just making the API inconsistent
> since if you support delete_bufs, then why support it for one queue only and not both?

Because the both queues don't handle the same type of data.
For example for a stateless decoder, for me, it makes sense to allow delete decoded frames
if they won't be used anymore but that won't makes sense for bitstream buffers.

> >   
> >   	return vb2_queue_init(dst_vq);
> >   }
> > diff --git a/drivers/media/platform/verisilicon/hantro_v4l2.c b/drivers/media/platform/verisilicon/hantro_v4l2.c
> > index 941fa23c211a..34eab90e8a42 100644
> > --- a/drivers/media/platform/verisilicon/hantro_v4l2.c
> > +++ b/drivers/media/platform/verisilicon/hantro_v4l2.c
> > @@ -756,6 +756,7 @@ const struct v4l2_ioctl_ops hantro_ioctl_ops = {
> >   	.vidioc_dqbuf = v4l2_m2m_ioctl_dqbuf,
> >   	.vidioc_prepare_buf = v4l2_m2m_ioctl_prepare_buf,
> >   	.vidioc_create_bufs = v4l2_m2m_ioctl_create_bufs,
> > +	.vidioc_delete_bufs = v4l2_m2m_ioctl_delete_bufs,
> >   	.vidioc_expbuf = v4l2_m2m_ioctl_expbuf,
> >   
> >   	.vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
> In my view setting vidioc_delete_bufs should enable this feature, and if
> for some strange reason only one queue support it, then make a wrapper
> callback that returns an error when used with the wrong queue.
>
> Also note that patch 6/8 never checks for q->supports_delete_bufs in
> vb2_core_delete_bufs(), which is wrong!

I will fix that in next version.
Regards,
Benjamin

> Regards,
>
> 	Hans