Messages in this thread | | | Subject | Re: [PATCH] vb2: V4L2_BUF_FLAG_DONE is set after DQBUF | From | Hans Verkuil <> | Date | Mon, 20 Jun 2016 11:53:51 +0200 |
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On 06/20/2016 11:01 AM, Ricardo Ribalda Delgado wrote: > According to the doc, V4L2_BUF_FLAG_DONE is cleared after DQBUF: > > V4L2_BUF_FLAG_DONE 0x00000004 ... After calling the VIDIOC_QBUF or > VIDIOC_DQBUF it is always cleared ... > > Unfortunately, it seems that videobuf2 keeps it set after DQBUF. This > can be tested with vivid and dev_debug: > > [257604.338082] video1: VIDIOC_DQBUF: 71:33:25.00260479 index=3, > type=vid-cap, flags=0x00002004, field=none, sequence=163, > memory=userptr, bytesused=460800, offset/userptr=0x344b000, > length=460800 > > This patch changes the order when fill_user_buffer() is called, > to follow the documentation. > > Reported-by: Dimitrios Katsaros <patcherwork@gmail.com> > Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Sorry, this won't work. Calling __vb2_dqbuf will overwrite the state VB2_BUF_STATE_ERROR and so the V4L2_BUF_FLAG_ERROR flag will never be set. The same is true for the last 'if' in the __fill_v4l2_buffer() function.
I think it might be better to keep this code and instead change the vb2_internal_dqbuf function to just clear the DONE flag after calling vb2_core_dqbuf.
It would be nice to have a v4l2_compliance check for this as well.
Regards,
Hans
> --- > drivers/media/v4l2-core/videobuf2-core.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 633fc1ab1d7a..63981f28075e 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -1771,10 +1771,6 @@ int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb, > if (pindex) > *pindex = vb->index; > > - /* Fill buffer information for the userspace */ > - if (pb) > - call_void_bufop(q, fill_user_buffer, vb, pb); > - > /* Remove from videobuf queue */ > list_del(&vb->queued_entry); > q->queued_count--; > @@ -1784,6 +1780,10 @@ int vb2_core_dqbuf(struct vb2_queue *q, unsigned int *pindex, void *pb, > /* go back to dequeued state */ > __vb2_dqbuf(vb); > > + /* Fill buffer information for the userspace */ > + if (pb) > + call_void_bufop(q, fill_user_buffer, vb, pb); > + > dprintk(1, "dqbuf of buffer %d, with state %d\n", > vb->index, vb->state); > >
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