Re: [PATCH 5/8] media: cedrus: Detect first slice of a frame

From: Jernej Åkrabec
Date: Mon Aug 26 2019 - 14:48:10 EST


Dne ponedeljek, 26. avgust 2019 ob 20:28:31 CEST je Boris Brezillon
napisal(a):
> Hi Jernej,
>
> On Thu, 22 Aug 2019 21:44:57 +0200
>
> Jernej Skrabec <jernej.skrabec@xxxxxxxx> wrote:
> > When codec supports multiple slices in one frame, VPU has to know when
> > first slice of each frame is being processed, presumably to correctly
> > clear/set data in auxiliary buffers.
> >
> > Add first_slice field to cedrus_run structure and set it according to
> > timestamps of capture and output buffers. If timestamps are different,
> > it's first slice and viceversa.
> >
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxx>
> > ---
> >
> > drivers/staging/media/sunxi/cedrus/cedrus.h | 1 +
> > drivers/staging/media/sunxi/cedrus/cedrus_dec.c | 2 ++
> > 2 files changed, 3 insertions(+)
> >
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.h
> > b/drivers/staging/media/sunxi/cedrus/cedrus.h index
> > 2f017a651848..32cb38e541c6 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus.h
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus.h
> > @@ -70,6 +70,7 @@ struct cedrus_mpeg2_run {
> >
> > struct cedrus_run {
> >
> > struct vb2_v4l2_buffer *src;
> > struct vb2_v4l2_buffer *dst;
> >
> > + bool first_slice;
> >
> > union {
> >
> > struct cedrus_h264_run h264;
> >
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> > b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c index
> > 56ca4c9ad01c..d7b54accfe83 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> > @@ -31,6 +31,8 @@ void cedrus_device_run(void *priv)
> >
> > run.src = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
> > run.dst = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
> >
> > + run.first_slice =
> > + run.src->vb2_buf.timestamp != run.dst-
>vb2_buf.timestamp;
>
> Can't we use slice->first_mb_in_slice to determine if a slice is the
> first? I'd expect ->first_mb_in_slice to be 0 (unless we decide to
> support ASO).

I'm not sure if that is always the case, I would have to check the standard.
Anyway, this method of comparing timestamps was suggested to me a while ago
when we were discussing details on a way forward for multi-slice decoding. I
highly doubt someone would decode slices in mixed order (from different frames)
in same instance.

I can change that in next version if ->first_mb_in_slice == 0 is always true
for the first slice.

Best regards,
Jernej

>
> > /* Apply request(s) controls if needed. */
> > src_req = run.src->vb2_buf.req_obj.req;