[media] v4l2: vb2: one more fix for REQBUFS()

Return immediately if the target number of buffers is the same as
the current one and memory access type doesn't change.
Signed-off-by: NMarek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/videobuf2-core.c

@@ -488,6 +488,13 @@ int vb2_reqbufs(struct vb2_queue *q, struct v4l2_requestbuffers *req)
 		return -EINVAL;
 	}
 
+	/*
+	 * If the same number of buffers and memory access method is requested
+	 * then return immediately.
+	 */
+	if (q->memory == req->memory && req->count == q->num_buffers)
+		return 0;
+
 	if (req->count == 0 || q->num_buffers != 0 || q->memory != req->memory) {
 		/*
 		 * We already have buffers allocated, so first check if they