usb: gadget: uvc: only schedule stream in streaming state

This patch ensures that the video pump thread will only be scheduled if
the uvc is really in streaming state. This way the worker will not have
to run on an empty queue.
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20211017215017.18392-5-m.grzeschik@pengutronix.deSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/function/uvc_v4l2.c

@@ -169,6 +169,7 @@ uvc_v4l2_qbuf(struct file *file, void *fh, struct v4l2_buffer *b)
 	if (ret < 0)
 		return ret;
 
+	if (uvc->state == UVC_STATE_STREAMING)
 		schedule_work(&video->pump);
 
 	return ret;

drivers/usb/gadget/function/uvc_video.c

@@ -216,6 +216,7 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 	struct uvc_request *ureq = req->context;
 	struct uvc_video *video = ureq->video;
 	struct uvc_video_queue *queue = &video->queue;
+	struct uvc_device *uvc = video->uvc;
 	unsigned long flags;
 
 	switch (req->status) {
@@ -238,6 +239,7 @@ uvc_video_complete(struct usb_ep *ep, struct usb_request *req)
 	list_add_tail(&req->list, &video->req_free);
 	spin_unlock_irqrestore(&video->req_lock, flags);
 
+	if (uvc->state == UVC_STATE_STREAMING)
 		schedule_work(&video->pump);
 }