linux-kernel - Re: [PATCH v2 9/9] media: uvcvideo: Support granular power saving for compat syscalls

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Message-ID: <2310d445-e288-424c-a295-4e5ac4507012@jjverkuil.nl>
Date: Mon, 30 Jun 2025 15:39:36 +0200
From: hans@...erkuil.nl
To: Ricardo Ribalda <ribalda@...omium.org>,
 Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Hans de Goede <hdegoede@...hat.com>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil <hverkuil@...all.nl>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 9/9] media: uvcvideo: Support granular power saving for
 compat syscalls

On 02/06/2025 15:06, Ricardo Ribalda wrote:
> Right now we cannot support granular power saving on compat syscalls
> because the VIDIOC_*32 NRs defines are not accessible to drivers.
> 
> Use the v4l2_compat_translate_cmd  helper to convert the compat syscall
> NRs into syscall NRs.

As mentioned, this should just be combined with patch 7/9. It's silly
and confusing to do this in two steps.

Regards,

	Hans

> 
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
>  drivers/media/usb/uvc/uvc_v4l2.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 13388879091c46ff74582226146521b5b5eb3d10..8358ca54b248dd1cf7c984b206b8e550cd883e54 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -1237,15 +1237,13 @@ static long uvc_v4l2_pm_ioctl(struct file *file,
>  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.
> -	 */
> +	unsigned int converted_cmd = cmd;
> +
>  	if (in_compat_syscall())
> -		return uvc_v4l2_pm_ioctl(file, cmd, arg);
> +		converted_cmd = v4l2_compat_translate_cmd(cmd);
>  
>  	/* The following IOCTLs do need to turn on the camera. */
> -	switch (cmd) {
> +	switch (converted_cmd) {
>  	case UVCIOC_CTRL_QUERY:
>  	case VIDIOC_G_CTRL:
>  	case VIDIOC_G_EXT_CTRLS:
>