v4l2: v4l2_camera_proxy: noop if streamon when stream is already on

If VIDIOC_STREMAON is called when the stream is already on, do a noop.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/v4l2/v4l2_camera_proxy.cpp

@@ -623,6 +623,9 @@ int V4L2CameraProxy::vidioc_streamon(V4L2CameraFile *file, int *arg)
 	if (!hasOwnership(file))
 		return -EBUSY;
 
+	if (vcam_->isRunning())
+		return 0;
+
 	currentBuf_ = 0;
 
 	return vcam_->streamOn();