From e35e41b57624b9a8c0014420cdfb24454e4773c5 Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Mon, 7 Apr 2014 09:20:39 -0300 Subject: [PATCH] [media] vb2: reject output buffers with V4L2_FIELD_ALTERNATE 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 Acked-by: Pawel Osciak Acked-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab --- 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 07ab067..2eef5ef 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -1564,6 +1564,19 @@ 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; -- 2.7.4