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

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Date:   Fri, 30 Aug 2019 09:28:08 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Jernej Skrabec <jernej.skrabec@...l.net>, mchehab@...nel.org,
        paul.kocialkowski@...tlin.com, mripard@...nel.org
Cc:     pawel@...iak.com, m.szyprowski@...sung.com,
        kyungmin.park@...sung.com, tfiga@...omium.org, wens@...e.org,
        acourbot@...omium.org, gregkh@...uxfoundation.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devel@...verdev.osuosl.org, linux-arm-kernel@...ts.infradead.org,
        ezequiel@...labora.com, jonas@...boo.se
Subject: Re: [PATCH 5/8] media: cedrus: Detect first slice of a frame

On 8/22/19 9:44 PM, Jernej Skrabec 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@...l.net>
> ---
>  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;

This is almost correct. To handle the corner case where no timestamp
was ever copied to run.dst->vb2_buf you need this check:

	run.first_slice = !run.dst->vb2_buf.copied_timestamp ||
		run.src->vb2_buf.timestamp != run.dst->vb2_buf.timestamp;

Regards,

	Hans

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