Re: [PATCH] media: rkvdec: set ctx->image_fmt in rkvdec_s_capture_fmt

[Jonas Karlman <jonas@kwiboo.se>]

Hi,

On 12/12/2025 4:41 PM, Jianfeng Liu wrote:
> ctx->image_fmt is initialized as RKVDEC_IMG_FMT_ANY at
> rkvdec_s_output_fmt, and get set at rkvdec_s_ctrl when userspace sends
> SPS info via VIDIOC_S_EXT_CTRLS. This works fine with gstreamer because
> it sends SPS info to kernel driver before requesting capture queue bufs.
> 
> But chromium requests capture queue bufs first and then sends SPS info
> to kernel, then rkvdec_s_ctrl will return -EBUSY, and the video is
> displayed green.
> 
> Chromium calls VIDIOC_S_FMT to capture queue instead before requesting
> capture queue bufs, so setting ctx->image_fmt in rkvdec_s_capture_fmt
> will make rkvdec_s_ctrl return 0 when the first SPS info sent to driver.
> 
> Signed-off-by: Jianfeng Liu <liujianfeng1994@gmail.com>
> Fixes: d35c64eccf3b1 ("media: rkvdec: Add get_image_fmt ops")
> ---
> 
>  drivers/media/platform/rockchip/rkvdec/rkvdec.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/media/platform/rockchip/rkvdec/rkvdec.c b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> index 5af9aa5ab353..e7939d604f64 100644
> --- a/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> +++ b/drivers/media/platform/rockchip/rkvdec/rkvdec.c
> @@ -537,6 +537,18 @@ static int rkvdec_s_capture_fmt(struct file *file, void *priv,
>  		return ret;
>  
>  	ctx->decoded_fmt = *f;
> +
> +	u32 fourcc = f->fmt.pix_mp.pixelformat;
> +
> +	if (fourcc == V4L2_PIX_FMT_NV12)
> +		ctx->image_fmt = RKVDEC_IMG_FMT_420_8BIT;
> +	else if (fourcc == V4L2_PIX_FMT_NV15)
> +		ctx->image_fmt = RKVDEC_IMG_FMT_420_10BIT;
> +	else if (fourcc == V4L2_PIX_FMT_NV16)
> +		ctx->image_fmt = RKVDEC_IMG_FMT_422_8BIT;
> +	else if (fourcc == V4L2_PIX_FMT_NV20)
> +		ctx->image_fmt = RKVDEC_IMG_FMT_422_10BIT;

ctx->image_fmt is used to limit what CAPTURE pixel format can be set and
forcing it here violates this.

Chromium should be fixed to follow spec at 4.5.3.2. Initialization [1]:

  1. Set the coded format on the OUTPUT queue via VIDIOC_S_FMT().
  2. Call VIDIOC_S_EXT_CTRLS() to set all the controls (parsed headers,
     etc.) required by the OUTPUT format to enumerate the CAPTURE formats.
  ...
  5. [optional] Choose a different CAPTURE format than suggested via
     VIDIOC_S_FMT() on CAPTURE queue.

Regards,
Jonas

[1] https://docs.kernel.org/userspace-api/media/v4l/dev-stateless-decoder.html

> +
>  	return 0;
>  }
>