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

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Message-ID: <6f6c7a57-7d51-4902-8ece-c661427f2290@kernel.org>
Date: Mon, 30 Jun 2025 15:21:54 +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 16-Jun-25 4:14 PM, Hans de Goede wrote:
> 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/

Actually this review-remark belongs to when this comment is re-added
below ...

>> -	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. */

So the 's/do need/need/' should be done here. I can fix this
up while merging. All that is necessary to merge this is an
ack from Hans V for merging the EXPORT in the core through
the UVC git tree.

Regards,

Hans



>> +	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,
>>
>