[media] media: usb: uvc: use vb2_ops_wait_prepare/finish helper

This patch drops driver specific wait_prepare() and wait_finish()
callbacks from vb2_ops and instead uses the the helpers
vb2_ops_wait_prepare/finish() provided by the vb2 core, the lock member
of the queue needs to be initalized to a mutex so that vb2 helpers
vb2_ops_wait_prepare/finish() can make use of it.
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/uvc/uvc_queue.c

@@ -143,20 +143,6 @@ static void uvc_buffer_finish(struct vb2_buffer *vb)
 		uvc_video_clock_update(stream, &vb->v4l2_buf, buf);
 }
 
-static void uvc_wait_prepare(struct vb2_queue *vq)
-{
-	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
-
-	mutex_unlock(&queue->mutex);
-}
-
-static void uvc_wait_finish(struct vb2_queue *vq)
-{
-	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
-
-	mutex_lock(&queue->mutex);
-}
-
 static int uvc_start_streaming(struct vb2_queue *vq, unsigned int count)
 {
 	struct uvc_video_queue *queue = vb2_get_drv_priv(vq);
@@ -195,8 +181,8 @@ static struct vb2_ops uvc_queue_qops = {
 	.buf_prepare = uvc_buffer_prepare,
 	.buf_queue = uvc_buffer_queue,
 	.buf_finish = uvc_buffer_finish,
-	.wait_prepare = uvc_wait_prepare,
-	.wait_finish = uvc_wait_finish,
+	.wait_prepare = vb2_ops_wait_prepare,
+	.wait_finish = vb2_ops_wait_finish,
 	.start_streaming = uvc_start_streaming,
 	.stop_streaming = uvc_stop_streaming,
 };
@@ -214,6 +200,7 @@ int uvc_queue_init(struct uvc_video_queue *queue, enum v4l2_buf_type type,
 	queue->queue.mem_ops = &vb2_vmalloc_memops;
 	queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
 		| V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
+	queue->queue.lock = &queue->mutex;
 	ret = vb2_queue_init(&queue->queue);
 	if (ret)
 		return ret;