On Wed, 26 Jun 2019 13:44:23 +0200, Hans Verkuil wrote:
> On 6/25/19 4:11 PM, Michael Tretter wrote:
> > When reaching the end of stream, V4L2 m2m clients may expect the
> > V4L2_EOS_EVENT. Although the V4L2_EOS_EVENT is deprecated behavior,
> > drivers must signal that event before dequeuing the buffer that has the
> > V4L2_BUF_FLAG_LAST flag set.
> >
> > If a driver queues the V4L2_EOS_EVENT event and returns the buffer after
> > the check for events but before the check for buffers, vb2_m2m_poll()
> > will signal that the buffer with V4L2_BUF_FLAG_LAST can be read but not
> > that the V4L2_EOS_EVENT is available.
> >
> > Split the check for buffers into a separate function and check for
> > available buffers before checking for events. This ensures that if
> > vb2_m2m_poll() signals POLLIN | POLLRDNORM for the V4L2_BUF_FLAG_LAST
> > buffer, it signals POLLPRI for the V4L2_EOS_EVENT, too.
> >
> > Signed-off-by: Michael Tretter <m.tretter@xxxxxxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-mem2mem.c | 47 +++++++++++++++-----------
> > 1 file changed, 27 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-mem2mem.c b/drivers/media/v4l2-core/v4l2-mem2mem.c
> > index 4f5176702937..f18fdce31d6f 100644
> > --- a/drivers/media/v4l2-core/v4l2-mem2mem.c
> > +++ b/drivers/media/v4l2-core/v4l2-mem2mem.c
> > @@ -603,11 +603,10 @@ int v4l2_m2m_streamoff(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > }
> > EXPORT_SYMBOL_GPL(v4l2_m2m_streamoff);
> >
> > -__poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > - struct poll_table_struct *wait)
> > +static __poll_t __v4l2_m2m_poll(struct file *file,
> > + struct v4l2_m2m_ctx *m2m_ctx,
> > + struct poll_table_struct *wait)
>
> I agree with the patch, except for this function name.
>
> How about: v4l2_m2m_poll_for_data() or something along those lines?
I don't have a strong opinion regarding the function name. I will send
a v2 with v4l2_m2m_poll_for_data().
Michael
>
> Regards,
>
> Hans
>
> > {
> > - struct video_device *vfd = video_devdata(file);
> > - __poll_t req_events = poll_requested_events(wait);
> > struct vb2_queue *src_q, *dst_q;
> > struct vb2_buffer *src_vb = NULL, *dst_vb = NULL;
> > __poll_t rc = 0;
> > @@ -619,16 +618,6 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > poll_wait(file, &src_q->done_wq, wait);
> > poll_wait(file, &dst_q->done_wq, wait);
> >
> > - if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags)) {
> > - struct v4l2_fh *fh = file->private_data;
> > -
> > - poll_wait(file, &fh->wait, wait);
> > - if (v4l2_event_pending(fh))
> > - rc = EPOLLPRI;
> > - if (!(req_events & (EPOLLOUT | EPOLLWRNORM | EPOLLIN | EPOLLRDNORM)))
> > - return rc;
> > - }
> > -
> > /*
> > * There has to be at least one buffer queued on each queued_list, which
> > * means either in driver already or waiting for driver to claim it
> > @@ -637,10 +626,8 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > if ((!src_q->streaming || src_q->error ||
> > list_empty(&src_q->queued_list)) &&
> > (!dst_q->streaming || dst_q->error ||
> > - list_empty(&dst_q->queued_list))) {
> > - rc |= EPOLLERR;
> > - goto end;
> > - }
> > + list_empty(&dst_q->queued_list)))
> > + return EPOLLERR;
> >
> > spin_lock_irqsave(&dst_q->done_lock, flags);
> > if (list_empty(&dst_q->done_list)) {
> > @@ -650,7 +637,7 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > */
> > if (dst_q->last_buffer_dequeued) {
> > spin_unlock_irqrestore(&dst_q->done_lock, flags);
> > - return rc | EPOLLIN | EPOLLRDNORM;
> > + return EPOLLIN | EPOLLRDNORM;
> > }
> > }
> > spin_unlock_irqrestore(&dst_q->done_lock, flags);
> > @@ -673,7 +660,27 @@ __poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > rc |= EPOLLIN | EPOLLRDNORM;
> > spin_unlock_irqrestore(&dst_q->done_lock, flags);
> >
> > -end:
> > + return rc;
> > +}
> > +
> > +__poll_t v4l2_m2m_poll(struct file *file, struct v4l2_m2m_ctx *m2m_ctx,
> > + struct poll_table_struct *wait)
> > +{
> > + struct video_device *vfd = video_devdata(file);
> > + __poll_t req_events = poll_requested_events(wait);
> > + __poll_t rc = 0;
> > +
> > + if (req_events & (EPOLLOUT | EPOLLWRNORM | EPOLLIN | EPOLLRDNORM))
> > + rc = __v4l2_m2m_poll(file, m2m_ctx, wait);
> > +
> > + if (test_bit(V4L2_FL_USES_V4L2_FH, &vfd->flags)) {
> > + struct v4l2_fh *fh = file->private_data;
> > +
> > + poll_wait(file, &fh->wait, wait);
> > + if (v4l2_event_pending(fh))
> > + rc |= EPOLLPRI;
> > + }
> > +
> > return rc;
> > }
> > EXPORT_SYMBOL_GPL(v4l2_m2m_poll);
> >
>
>
