On Mon, Apr 7, 2014 at 10:11 PM, Hans Verkuil <hverkuil@xxxxxxxxx> wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> This is not allowed by the spec and does in fact not make any sense.
> Return -EINVAL if this is the case.
>
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Acked-by: Pawel Osciak <pawel@xxxxxxxxxx>
> ---
> drivers/media/v4l2-core/videobuf2-core.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index b7de6be..c662ad9 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -1511,6 +1511,19 @@ static int __buf_prepare(struct vb2_buffer *vb, const struct v4l2_buffer *b)
> dprintk(1, "plane parameters verification failed: %d\n", ret);
> return ret;
> }
> + if (b->field == V4L2_FIELD_ALTERNATE && V4L2_TYPE_IS_OUTPUT(q->type)) {
> + /*
> + * If the format's field is ALTERNATE, then the buffer's field
> + * should be either TOP or BOTTOM, not ALTERNATE since that
> + * makes no sense. The driver has to know whether the
> + * buffer represents a top or a bottom field in order to
> + * program any DMA correctly. Using ALTERNATE is wrong, since
> + * that just says that it is either a top or a bottom field,
> + * but not which of the two it is.
> + */
> + dprintk(1, "the field is incorrectly set to ALTERNATE for an output buffer\n");
> + return -EINVAL;
> + }
>
> vb->state = VB2_BUF_STATE_PREPARING;
> vb->v4l2_buf.timestamp.tv_sec = 0;
> --
> 1.9.1
>
--
Best regards,
Pawel Osciak
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