linux-kernel - Re: [PATCH v3 8/8] media: uvcvideo: uvc_v4l2_unlocked

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Message-ID: <20250630222546.GC15184@pendragon.ideasonboard.com>
Date: Tue, 1 Jul 2025 01:25:46 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Ricardo Ribalda <ribalda@...omium.org>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
	Hans Verkuil <hverkuil@...all.nl>, Hans de Goede <hansg@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	Hans Verkuil <hans@...erkuil.nl>
Subject: Re: [PATCH v3 8/8] media: uvcvideo: uvc_v4l2_unlocked_ioctl: Invert
 PM logic

Hi Ricardo,

On Mon, Jun 30, 2025 at 02:20:33PM +0000, Ricardo Ribalda wrote:
> Instead of listing the IOCTLs that do not need to turn on the camera,
> list the IOCTLs that need to turn it on. This makes the code more
> maintainable.
> 
> This patch changes the behaviour for unsupported IOCTLs. Those IOCTLs
> will not turn on the camera.

The idea is good, but you'll have to add UVCIOC_CTRL_MAP back (see 6/8).

> Suggested-by: Hans Verkuil <hans@...erkuil.nl>
> Reviewed-by: Hans de Goede <hansg@...nel.org>
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/usb/uvc/uvc_v4l2.c | 52 +++++++++++++++++++---------------------
>  1 file changed, 25 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 350cd2cc88f872d2e8bd19e2b8fb067894916364..94dc97448446d36a85a1b36d16c29f22af89c640 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -1222,37 +1222,35 @@ static long uvc_v4l2_unlocked_ioctl(struct file *file,
>  				    unsigned int cmd, unsigned long arg)
>  {
>  	struct uvc_fh *handle = file->private_data;
> +	unsigned int converted_cmd = v4l2_translate_cmd(cmd);
>  	int ret;
>  
> -	/* The following IOCTLs do not need to turn on the camera. */
> -	switch (cmd) {
> -	case UVCIOC_CTRL_MAP:
> -	case VIDIOC_CREATE_BUFS:
> -	case VIDIOC_DQBUF:
> -	case VIDIOC_ENUM_FMT:
> -	case VIDIOC_ENUM_FRAMEINTERVALS:
> -	case VIDIOC_ENUM_FRAMESIZES:
> -	case VIDIOC_ENUMINPUT:
> -	case VIDIOC_EXPBUF:
> -	case VIDIOC_G_FMT:
> -	case VIDIOC_G_PARM:
> -	case VIDIOC_G_SELECTION:
> -	case VIDIOC_QBUF:
> -	case VIDIOC_QUERYCAP:
> -	case VIDIOC_REQBUFS:
> -	case VIDIOC_SUBSCRIBE_EVENT:
> -	case VIDIOC_UNSUBSCRIBE_EVENT:
> -		return video_ioctl2(file, cmd, arg);
> -	}
> -
> -	ret = uvc_pm_get(handle->stream->dev);
> -	if (ret)
> +	/* The following IOCTLs need to turn on the camera. */
> +	switch (converted_cmd) {
> +	case UVCIOC_CTRL_QUERY:
> +	case VIDIOC_G_CTRL:
> +	case VIDIOC_G_EXT_CTRLS:
> +	case VIDIOC_G_INPUT:
> +	case VIDIOC_QUERYCTRL:
> +	case VIDIOC_QUERYMENU:
> +	case VIDIOC_QUERY_EXT_CTRL:
> +	case VIDIOC_S_CTRL:
> +	case VIDIOC_S_EXT_CTRLS:
> +	case VIDIOC_S_FMT:
> +	case VIDIOC_S_INPUT:
> +	case VIDIOC_S_PARM:
> +	case VIDIOC_TRY_EXT_CTRLS:
> +	case VIDIOC_TRY_FMT:
> +		ret = uvc_pm_get(handle->stream->dev);
> +		if (ret)
> +			return ret;
> +		ret = video_ioctl2(file, cmd, arg);
> +		uvc_pm_put(handle->stream->dev);
>  		return ret;
> +	}
>  
> -	ret = video_ioctl2(file, cmd, arg);
> -
> -	uvc_pm_put(handle->stream->dev);
> -	return ret;
> +	/* The other IOCTLs can run with the camera off. */
> +	return video_ioctl2(file, cmd, arg);
>  }
>  
>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {

-- 
Regards,

Laurent Pinchart