linux-kernel - Re: [PATCH] media: mediatek: vcodec: Fix v4l2 compliance decoder cmd test fail

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Date:   Thu, 21 Apr 2022 12:47:58 +0200
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Yunfei Dong <yunfei.dong@...iatek.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Nicolas Dufresne <nicolas@...fresne.ca>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Benjamin Gaignard <benjamin.gaignard@...labora.com>,
        Tiffany Lin <tiffany.lin@...iatek.com>,
        Andrew-CT Chen <andrew-ct.chen@...iatek.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Tomasz Figa <tfiga@...gle.com>
Cc:     George Sun <george.sun@...iatek.com>,
        Xiaoyong Lu <xiaoyong.lu@...iatek.com>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Fritz Koenig <frkoenig@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Irui Wang <irui.wang@...iatek.com>,
        Steve Cho <stevecho@...omium.org>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, srv_heupstream@...iatek.com,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH] media: mediatek: vcodec: Fix v4l2 compliance decoder cmd
 test fail

On 06/04/2022 03:20, Yunfei Dong wrote:
> Will return -EINVAL using standard framework api when test stateless
> decoder with cmd VIDIOC_(TRY)DECODER_CMD.
> 
> Using another return value to adjust v4l2 compliance test for user
> driver(GStreamer/Chrome) won't use decoder cmd.
> 
> Fixes: 8cdc3794b2e3 ("media: mtk-vcodec: vdec: support stateless API")
> Signed-off-by: Yunfei Dong <yunfei.dong@...iatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
> ---
> changes compared with v2:
> - add reviewed-by tag
> changes compared with v1:
> - add Fixes: tag
> ---
>  drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c
> index 3859e4c651c6..69b0e797d342 100644
> --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c
> +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c
> @@ -51,8 +51,7 @@ static int vidioc_try_decoder_cmd(struct file *file, void *priv,
>  
>  	/* Use M2M stateless helper if relevant */
>  	if (ctx->dev->vdec_pdata->uses_stateless_api)
> -		return v4l2_m2m_ioctl_stateless_try_decoder_cmd(file, priv,
> -								cmd);
> +		return -ENOTTY;
>  	else
>  		return v4l2_m2m_ioctl_try_decoder_cmd(file, priv, cmd);
>  }

So in other words, if the stateless api is used, then (TRY_)DECODER_CMD
is not implemented. And that's because this driver doesn't set the
V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF capability as that's not needed.
And so there is no need for (TRY_)DECODER_CMD to be implemented.

If that's the case, then it is much better to just disable these two
ioctls with v4l2_disable_ioctl() if the stateless API is used.

And just drop the uses_stateless_api checks in both vidioc_try_decoder_cmd
and vidioc_decoder_cmd. This patch only changed vidioc_try_decoder_cmd,
but of course vidioc_decoder_cmd needs to be modified as well.

Regards,

	Hans