Re: [PATCH v5 4/5] media: uvcvideo: Make power management granular

From: Laurent Pinchart
Date: Thu Mar 27 2025 - 13:56:44 EST


Hi Ricardo,

Thank you for the patch.

On Mon, Mar 03, 2025 at 07:13:41PM +0000, Ricardo Ribalda wrote:
> Now that every ioctl takes care of their power management we can remove
> the "global" power management.
>
> Despite its size, this is a relatively big change. We hope that there
> are no size effects of it. If there are some specific devices that
> miss-behave, we can add a small quirk for them.
>
> This patch introduces a behavioral change for the uvc "trigger" button.
> Before the "trigger" button would work as long as userspace has opened
> /dev/videoX. Now it only works when the camera is actually streaming. We
> consider that this the most common (if not the only) usecase and
> therefore we do not think of this as a regression.

We'll see :-)

> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>

Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>

> ---
> drivers/media/usb/uvc/uvc_v4l2.c | 8 --------
> 1 file changed, 8 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 1c9ac72be58a..6af93e00b304 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -652,7 +652,6 @@ static int uvc_v4l2_open(struct file *file)
> {
> struct uvc_streaming *stream;
> struct uvc_fh *handle;
> - int ret = 0;
>
> stream = video_drvdata(file);
> uvc_dbg(stream->dev, CALLS, "%s\n", __func__);
> @@ -662,12 +661,6 @@ static int uvc_v4l2_open(struct file *file)
> if (!handle)
> return -ENOMEM;
>
> - ret = uvc_pm_get(stream->dev);
> - if (ret) {
> - kfree(handle);
> - return ret;
> - }
> -
> v4l2_fh_init(&handle->vfh, &stream->vdev);
> v4l2_fh_add(&handle->vfh);
> handle->chain = stream->chain;
> @@ -701,7 +694,6 @@ static int uvc_v4l2_release(struct file *file)
> kfree(handle);
> file->private_data = NULL;
>
> - uvc_pm_put(stream->dev);
> return 0;
> }
>

--
Regards,

Laurent Pinchart