linux-kernel - [PATCH v6 1/5] media: uvcvideo: Keep streaming state in the file handle

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Message-Id: <20250327-uvc-granpower-ng-v6-1-35a2357ff348@chromium.org>
Date: Thu, 27 Mar 2025 21:05:27 +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 1/5] media: uvcvideo: Keep streaming state in the file
 handle

Add a variable in the file handle state to figure out if a camera is in
the streaming state or not. This variable will be used in the future for
power management policies.

Now that we are at it, make use of guards to simplify the code.

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
Reviewed-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/usb/uvc/uvc_v4l2.c | 18 +++++++++++++-----
 drivers/media/usb/uvc/uvcvideo.h |  1 +
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 39065db44e864b8d107659197dac9ac33b01cf46..22886b47d81c2cfd0a744f34a50d296d606e54e8 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -841,11 +841,18 @@ static int uvc_ioctl_streamon(struct file *file, void *fh,
 	if (!uvc_has_privileges(handle))
 		return -EBUSY;
 
-	mutex_lock(&stream->mutex);
+	guard(mutex)(&stream->mutex);
+
+	if (handle->is_streaming)
+		return 0;
+
 	ret = uvc_queue_streamon(&stream->queue, type);
-	mutex_unlock(&stream->mutex);
+	if (ret)
+		return ret;
 
-	return ret;
+	handle->is_streaming = true;
+
+	return 0;
 }
 
 static int uvc_ioctl_streamoff(struct file *file, void *fh,
@@ -857,9 +864,10 @@ static int uvc_ioctl_streamoff(struct file *file, void *fh,
 	if (!uvc_has_privileges(handle))
 		return -EBUSY;
 
-	mutex_lock(&stream->mutex);
+	guard(mutex)(&stream->mutex);
+
 	uvc_queue_streamoff(&stream->queue, type);
-	mutex_unlock(&stream->mutex);
+	handle->is_streaming = false;
 
 	return 0;
 }
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index b4ee701835fc016474d2cd2a0b67b2aa915c1c60..5ceb01e7831a83507550e1d3313e63da7494b2e4 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -630,6 +630,7 @@ struct uvc_fh {
 	struct uvc_streaming *stream;
 	enum uvc_handle_state state;
 	unsigned int pending_async_ctrls;
+	bool is_streaming;
 };
 
 /* ------------------------------------------------------------------------

-- 
2.49.0.472.ge94155a9ec-goog