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Date:   Mon, 26 Aug 2019 20:28:31 +0200
From:   Boris Brezillon <boris.brezillon@collabora.com>
To:     Jernej Skrabec <jernej.skrabec@siol.net>
Cc:     mchehab@kernel.org, hverkuil-cisco@xs4all.nl,
        paul.kocialkowski@bootlin.com, mripard@kernel.org,
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        kyungmin.park@samsung.com, tfiga@chromium.org, wens@csie.org,
        acourbot@chromium.org, gregkh@linuxfoundation.org,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        devel@driverdev.osuosl.org, linux-arm-kernel@lists.infradead.org,
        ezequiel@collabora.com, jonas@kwiboo.se
Subject: Re: [PATCH 5/8] media: cedrus: Detect first slice of a frame
Message-ID: <20190826202831.311c7c20@collabora.com>
In-Reply-To: <20190822194500.2071-6-jernej.skrabec@siol.net>
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        <20190822194500.2071-6-jernej.skrabec@siol.net>
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Hi Jernej,

On Thu, 22 Aug 2019 21:44:57 +0200
Jernej Skrabec <jernej.skrabec@siol.net> 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@siol.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;

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).

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