linux-kernel - Re: [PATCH 2/3] media: cedrus: h264: Properly configure reference field

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Date:   Fri, 05 Jun 2020 13:16:35 -0400
From:   Nicolas Dufresne <nicolas@...fresne.ca>
To:     Jernej Skrabec <jernej.skrabec@...l.net>,
        paul.kocialkowski@...tlin.com, mripard@...nel.org
Cc:     mchehab@...nel.org, wens@...e.org, hverkuil-cisco@...all.nl,
        gregkh@...uxfoundation.org, jonas@...boo.se,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devel@...verdev.osuosl.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 2/3] media: cedrus: h264: Properly configure reference
 field

Le jeudi 04 juin 2020 à 20:57 +0200, Jernej Skrabec a écrit :
> When interlaced H264 content is being decoded, references must indicate
> which field is being referenced. Currently this was done by checking
> capture buffer flags. However, that is not correct because capture
> buffer may hold both fields.
> 
> Fix this by checking newly introduced flags in reference lists.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>

Perhaps an additional patch could cleanup the miss-leading comment in
v4l2_h264_dpb_entry definition.

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>

> ---
>  drivers/staging/media/sunxi/cedrus/cedrus_h264.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> index cce527bbdf86..c87717d17ec5 100644
> --- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> @@ -183,7 +183,6 @@ static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
>  	for (i = 0; i < num_ref; i++) {
>  		const struct v4l2_h264_dpb_entry *dpb;
>  		const struct cedrus_buffer *cedrus_buf;
> -		const struct vb2_v4l2_buffer *ref_buf;
>  		unsigned int position;
>  		int buf_idx;
>  		u8 dpb_idx;
> @@ -198,12 +197,11 @@ static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
>  		if (buf_idx < 0)
>  			continue;
>  
> -		ref_buf = to_vb2_v4l2_buffer(cap_q->bufs[buf_idx]);
> -		cedrus_buf = vb2_v4l2_to_cedrus_buffer(ref_buf);
> +		cedrus_buf = vb2_to_cedrus_buffer(cap_q->bufs[buf_idx]);
>  		position = cedrus_buf->codec.h264.position;
>  
>  		sram_array[i] |= position << 1;
> -		if (ref_buf->field == V4L2_FIELD_BOTTOM)
> +		if (ref_list[i].flags & V4L2_H264_REFERENCE_FLAG_BOTTOM_FIELD)
>  			sram_array[i] |= BIT(0);
>  	}
>