linux-kernel - Re: [PATCH v2 7/9] media: uvcvideo: uvc_v4l2_unlocked

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Message-ID: <ba461646-c639-4e66-9f6d-c34f59d39f82@kernel.org>
Date: Mon, 16 Jun 2025 16:14:15 +0200
From: Hans de Goede <hansg@...nel.org>
To: Ricardo Ribalda <ribalda@...omium.org>,
 Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil <hverkuil@...all.nl>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
 Hans Verkuil <hans@...erkuil.nl>
Subject: Re: [PATCH v2 7/9] media: uvcvideo: uvc_v4l2_unlocked_ioctl: Invert
 PM logic

Hi,

On 2-Jun-25 15:06, 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.
> 
> Suggested-by: Hans Verkuil <hans@...erkuil.nl>
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/usb/uvc/uvc_v4l2.c | 61 ++++++++++++++++++++++++----------------
>  1 file changed, 36 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 020def11b60e00ca2875dd96f23ef9591fed11d9..13388879091c46ff74582226146521b5b5eb3d10 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -1219,43 +1219,54 @@ static long uvc_v4l2_compat_ioctl32(struct file *file,
>  }
>  #endif
>  
> -static long uvc_v4l2_unlocked_ioctl(struct file *file,
> -				    unsigned int cmd, unsigned long arg)
> +static long uvc_v4l2_pm_ioctl(struct file *file,
> +			      unsigned int cmd, unsigned long arg)
>  {
>  	struct uvc_fh *handle = file->private_data;
>  	int ret;
>  
> -	/* The following IOCTLs do not need to turn on the camera. */

s/do need/need/

otherwise this looks good to me:

Reviewed-by: Hans de Goede <hansg@...nel.org>

Regards,

Hans


> -	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)
>  		return ret;
> -
>  	ret = video_ioctl2(file, cmd, arg);
> -
>  	uvc_pm_put(handle->stream->dev);
> +
>  	return ret;
>  }
>  
> +static long uvc_v4l2_unlocked_ioctl(struct file *file,
> +				    unsigned int cmd, unsigned long arg)
> +{
> +	/*
> +	 * For now, we do not support granular power saving for compat
> +	 * syscalls.
> +	 */
> +	if (in_compat_syscall())
> +		return uvc_v4l2_pm_ioctl(file, cmd, arg);
> +
> +	/* The following IOCTLs do need to turn on the camera. */
> +	switch (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:
> +		return uvc_v4l2_pm_ioctl(file, cmd, arg);
> +	}
> +
> +	/* The other IOCTLs can run with the camera off. */
> +	return video_ioctl2(file, cmd, arg);
> +}
> +
>  const struct v4l2_ioctl_ops uvc_ioctl_ops = {
>  	.vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
>  	.vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
>