linux-kernel - [PATCH v6 4/5] media: uvcvideo: Make power management granular

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Message-Id: <20250327-uvc-granpower-ng-v6-4-35a2357ff348@chromium.org>
Date: Thu, 27 Mar 2025 21:05:30 +0000
From: Ricardo Ribalda <ribalda@...omium.org>
To: Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Hans de Goede <hdegoede@...hat.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Guennadi Liakhovetski <guennadi.liakhovetski@...el.com>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Mauro Carvalho Chehab <mchehab+samsung@...nel.org>, 
 Ricardo Ribalda <ribalda@...omium.org>
Subject: [PATCH v6 4/5] media: uvcvideo: Make power management granular

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.

Reviewed-by: Hans de Goede <hdegoede@...hat.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 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 8bccf7e17528b62f2594c0dad99405034532973d..0f1ed0387b2611c8d21e211afe21a35101071d93 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -658,7 +658,6 @@ 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__);
@@ -668,12 +667,6 @@ 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;
@@ -707,7 +700,6 @@ static int uvc_v4l2_release(struct file *file)
 	kfree(handle);
 	file->private_data = NULL;
 
-	uvc_pm_put(stream->dev);
 	return 0;
 }
 

-- 
2.49.0.472.ge94155a9ec-goog