media: videobuf2-v4l2: refuse qbuf if queue uses requests or vv.

Check if the vb2 queue uses requests, and if so refuse to
add buffers that are not part of a request. Also check for
the reverse: a vb2 queue did not use requests, and an attempt
was made to queue a buffer to a request.

We might relax this in the future, but for now just return
-EPERM in that case.
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/common/videobuf2/videobuf2-v4l2.c

@@ -378,8 +378,16 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
 			return ret;
 	}
 
-	if (!(b->flags & V4L2_BUF_FLAG_REQUEST_FD))
+	if (!(b->flags & V4L2_BUF_FLAG_REQUEST_FD)) {
+		if (q->uses_requests) {
+			dprintk(1, "%s: queue uses requests\n", opname);
+			return -EPERM;
+		}
 		return 0;
+	} else if (q->uses_qbuf) {
+		dprintk(1, "%s: queue does not use requests\n", opname);
+		return -EPERM;
+	}
 
 	/*
 	 * For proper locking when queueing a request you need to be able