Em Tue, 16 Sep 2014 11:28:16 +0200 Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > (My proposal to fix this. Note that it is untested, I plan to do that this > evening) > > Commit 9241650d62f7 broke vbi capture applications that expect POLLERR to be > returned if STREAMON wasn't called. > > Rather than checking whether buffers were queued AND vb2 was not yet streaming, > just check whether streaming is in progress and return POLLERR if not. > > This change makes it impossible to poll in one thread and call STREAMON in > another, but doing that breaks existing applications and is also not according > to the spec. So be it. > > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c > index 7e6aff6..0452fb2 100644 > --- a/drivers/media/v4l2-core/videobuf2-core.c > +++ b/drivers/media/v4l2-core/videobuf2-core.c > @@ -2583,10 +2583,10 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) > } > > /* > - * There is nothing to wait for if no buffer has been queued and the > - * queue isn't streaming, or if the error flag is set. > + * There is nothing to wait for if the queue isn't streaming, or if > + * the error flag is set. > */ > - if ((list_empty(&q->queued_list) && !vb2_is_streaming(q)) || q->error) > + if (!vb2_is_streaming(q) || q->error) > return res | POLLERR; This makes the code even more different than what VB1 does. I suspect that this will likely cause even more regressions. The following (untested) patch seems to be what matches best what VB1 does, and are likely to cause less harm, but needs test of course. diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c index 5b808e25fc09..0d86526cbcb0 100644 --- a/drivers/media/v4l2-core/videobuf2-core.c +++ b/drivers/media/v4l2-core/videobuf2-core.c @@ -2586,6 +2586,9 @@ unsigned int vb2_poll(struct vb2_queue *q, struct file *file, poll_table *wait) * There is nothing to wait for if no buffer has been queued and the * queue isn't streaming, or if the error flag is set. */ + if (!vb2_is_streaming(q)) + vb2_internal_streamon(q, q->type); + if ((list_empty(&q->queued_list) && !vb2_is_streaming(q)) || q->error) return res | POLLERR; -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
