[PATCHv4.1 5/5] vb2: check that buf_out_validate is present

[Hans Verkuil <hverkuil-cisco@xs4all.nl>]

The buf_out_validate is required for output queues in combination
with requests. Check this.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
---
Changes since v4:

- Check for VIDEO_OUTPUT types instead of q->is_output since this is not
  relevant for e.g. VBI outputs.
---
 drivers/media/common/videobuf2/videobuf2-v4l2.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 2f3b3ca5bde6..3aeaea3af42a 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -409,6 +409,15 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
 	 */
 	if (WARN_ON(!q->ops->buf_request_complete))
 		return -EINVAL;
+	/*
+	 * Make sure this op is implemented by the driver for the output queue.
+	 * It's easy to forget this callback, but is it important to correctly
+	 * validate the 'field' value at QBUF time.
+	 */
+	if (WARN_ON((q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT ||
+		     q->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) &&
+		    !q->ops->buf_out_validate))
+		return -EINVAL;

 	if (vb->state != VB2_BUF_STATE_DEQUEUED) {
 		dprintk(1, "%s: buffer is not in dequeued state\n", opname);
-- 
2.20.1