linux-kernel - Re: [PATCH 1/4] media: mediatek: vcodec: Fix decoder v4l2 bus

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Date:   Thu, 9 Jun 2022 12:08:50 +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,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH 1/4] media: mediatek: vcodec: Fix decoder v4l2 bus_info
 not correctly

Hi Yunfei Dong,

On 5/26/22 11:57, Yunfei Dong wrote:
> Fix v4l2 capability bus_info value with correct chip name according to compatible.
> 
> Signed-off-by: Yunfei Dong <yunfei.dong@...iatek.com>
> ---
>  .../platform/mediatek/vcodec/mtk_vcodec_dec.c | 23 ++++++++++++++++++-
>  1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c
> index 52e5d36aa912..ccfa426a34ab 100644
> --- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c
> +++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec.c
> @@ -185,11 +185,32 @@ static int vidioc_vdec_dqbuf(struct file *file, void *priv,
>  	return v4l2_m2m_dqbuf(file, ctx->m2m_ctx, buf);
>  }
>  
> +static int mtk_vcodec_dec_get_chip_name(void *priv)
> +{
> +	struct mtk_vcodec_ctx *ctx = fh_to_ctx(priv);
> +	struct device *dev = &ctx->dev->plat_dev->dev;
> +
> +	if (of_device_is_compatible(dev->of_node, "mediatek,mt8173-vcodec-dec"))
> +		return 8173;
> +	else if (of_device_is_compatible(dev->of_node, "mediatek,mt8183-vcodec-dec"))
> +		return 8183;
> +	else if (of_device_is_compatible(dev->of_node, "mediatek,mt8192-vcodec-dec"))
> +		return 8192;
> +	else if (of_device_is_compatible(dev->of_node, "mediatek,mt8195-vcodec-dec"))
> +		return 8195;
> +	else if (of_device_is_compatible(dev->of_node, "mediatek,mt8186-vcodec-dec"))
> +		return 8186;
> +	else
> +		return 8173;
> +}

Nice, but...

> +
>  static int vidioc_vdec_querycap(struct file *file, void *priv,
>  				struct v4l2_capability *cap)
>  {
> +	int platform_name = mtk_vcodec_dec_get_chip_name(priv);
> +
>  	strscpy(cap->driver, MTK_VCODEC_DEC_NAME, sizeof(cap->driver));
> -	strscpy(cap->bus_info, MTK_PLATFORM_STR, sizeof(cap->bus_info));
> +	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:mt%d", platform_name);

...this will result in identical bus_info values for the decoder and encoder
video devices. The bus_info field is supposed to be unique, and that's now
no longer the case.

I suggest changing this to:

	snprintf(cap->bus_info, sizeof(cap->bus_info), "platform:mt%d-dec", platform_name);

(and '-enc' for the encoder patch).

Regards,

	Hans

>  	strscpy(cap->card, MTK_PLATFORM_STR, sizeof(cap->card));
>  
>  	return 0;