Hi,
On Wed, 2019-01-09 at 15:29 +0100, Hans Verkuil wrote:
> On 01/09/19 15:19, Paul Kocialkowski wrote:
> > It was reported that some cases of interleaved video decoding require
> > using the current destination buffer as a reference. However, this is
> > no longer possible after the move to vb2_find_timestamp because only
> > dequeued and done buffers are considered.
> >
> > Add a helper in our driver that also considers the current destination
> > buffer before resorting to vb2_find_timestamp and use it in MPEG-2.
>
> This patch looks good, but can you also add checks to handle the case
> when no buffer with the given timestamp was found? Probably should be done
> in a third patch.
>
> I suspect the driver will crash if an unknown timestamp is passed on to the
> driver. I would really like to see that corner case fixed.
You're totally right and I think that more generarlly, the current code
flow is rather fragile whenever something wrong happens in our setup()
codec op. I think we should at least have that op return an error code
and properly deal with it when that occurs.
I am planning on making a cleanup series to fix that.
Before using timestamps, reference buffer index validation was done in
std_validate and now it's fully up to the driver. I wonder if it would
be feasible to bring something back in there since all stateless
drivers will face the same issue. The conditions set in
cedrus_reference_index_find seem generic enough for that, but we should
check that std_validate is not called too early, when the queue is in a
different state (and the buffer might not be dequeud or done yet).
What do you think?
Cheers,
Paul
> > Signed-off-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx>
> > ---
> > drivers/staging/media/sunxi/cedrus/cedrus_dec.c | 13 +++++++++++++
> > drivers/staging/media/sunxi/cedrus/cedrus_dec.h | 2 ++
> > drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c | 10 ++++++----
> > 3 files changed, 21 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> > index 443fb037e1cf..2c295286766c 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c
> > @@ -22,6 +22,19 @@
> > #include "cedrus_dec.h"
> > #include "cedrus_hw.h"
> >
> > +int cedrus_reference_index_find(struct vb2_queue *queue,
> > + struct vb2_buffer *vb2_buf, u64 timestamp)
> > +{
> > + /*
> > + * Allow using the current capture buffer as reference, which can occur
> > + * for field-coded pictures.
> > + */
> > + if (vb2_buf->timestamp == timestamp)
> > + return vb2_buf->index;
> > + else
> > + return vb2_find_timestamp(queue, timestamp, 0);
> > +}
> > +
> > void cedrus_device_run(void *priv)
> > {
> > struct cedrus_ctx *ctx = priv;
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.h b/drivers/staging/media/sunxi/cedrus/cedrus_dec.h
> > index d1ae7903677b..8d0fc248220f 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.h
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.h
> > @@ -16,6 +16,8 @@
> > #ifndef _CEDRUS_DEC_H_
> > #define _CEDRUS_DEC_H_
> >
> > +int cedrus_reference_index_find(struct vb2_queue *queue,
> > + struct vb2_buffer *vb2_buf, u64 timestamp);
> > void cedrus_device_run(void *priv);
> >
> > #endif
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c b/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> > index cb45fda9aaeb..81c66a8aa1ac 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_mpeg2.c
> > @@ -10,6 +10,7 @@
> > #include <media/videobuf2-dma-contig.h>
> >
> > #include "cedrus.h"
> > +#include "cedrus_dec.h"
> > #include "cedrus_hw.h"
> > #include "cedrus_regs.h"
> >
> > @@ -159,8 +160,8 @@ static void cedrus_mpeg2_setup(struct cedrus_ctx *ctx, struct cedrus_run *run)
> > cedrus_write(dev, VE_DEC_MPEG_PICBOUNDSIZE, reg);
> >
> > /* Forward and backward prediction reference buffers. */
> > - forward_idx = vb2_find_timestamp(cap_q,
> > - slice_params->forward_ref_ts, 0);
> > + forward_idx = cedrus_reference_index_find(cap_q, &run->dst->vb2_buf,
> > + slice_params->forward_ref_ts);
> >
> > fwd_luma_addr = cedrus_dst_buf_addr(ctx, forward_idx, 0);
> > fwd_chroma_addr = cedrus_dst_buf_addr(ctx, forward_idx, 1);
> > @@ -168,8 +169,9 @@ static void cedrus_mpeg2_setup(struct cedrus_ctx *ctx, struct cedrus_run *run)
> > cedrus_write(dev, VE_DEC_MPEG_FWD_REF_LUMA_ADDR, fwd_luma_addr);
> > cedrus_write(dev, VE_DEC_MPEG_FWD_REF_CHROMA_ADDR, fwd_chroma_addr);
> >
> > - backward_idx = vb2_find_timestamp(cap_q,
> > - slice_params->backward_ref_ts, 0);
> > + backward_idx = cedrus_reference_index_find(cap_q, &run->dst->vb2_buf,
> > + slice_params->backward_ref_ts);
> > +
> > bwd_luma_addr = cedrus_dst_buf_addr(ctx, backward_idx, 0);
> > bwd_chroma_addr = cedrus_dst_buf_addr(ctx, backward_idx, 1);
> >
> >
--
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com
_______________________________________________
devel mailing list
devel@xxxxxxxxxxxxxxxxxxxxxx
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
