On Fri September 21 2012 18:13:20 Sylwester Nawrocki wrote:
> Hi Hans,
>
> On 09/19/2012 04:37 PM, Hans Verkuil wrote:
> > From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> >
> > length should be set to num_planes in __fill_v4l2_buffer(). That way the
> > caller knows how many planes there are in the buffer.
> >
> > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
>
> I think this would break VIDIOC_CREATE_BUFS. We need per buffer num_planes.
> Consider a use case where device is streaming with 2-planar pixel format
> and we invoke VIDIOC_CREATE_BUFS with single-planar format. On a single
> queue there will be buffers with different number of planes. The number of
> planes information must be attached to a buffer, otherwise VIDIOC_QUERYBUF
> won't work.
That's a very good point and one I need to meditate on.
However, your comment applies to patch 1/6, not to this one.
This patch is about whether or not the length field of v4l2_buffer should
be filled in with the actual number of planes used by that buffer or not.
Regards,
Hans
>
> > ---
> > drivers/media/v4l2-core/videobuf2-core.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> > index 929cc99..bbfe022 100644
> > --- a/drivers/media/v4l2-core/videobuf2-core.c
> > +++ b/drivers/media/v4l2-core/videobuf2-core.c
> > @@ -348,6 +348,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, struct v4l2_buffer *b)
> > * Fill in plane-related data if userspace provided an array
> > * for it. The memory and size is verified above.
> > */
> > + b->length = q->num_planes;
> > memcpy(b->m.planes, vb->v4l2_planes,
> > b->length * sizeof(struct v4l2_plane));
> > } else {
>
> Regards,
> Sylwester
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