On Wed, 27 Apr 2011 16:10:57 +1000
christopher.halse.rogers@xxxxxxxxxxxxx wrote:
> From: Christopher James Halse Rogers <christopher.halse.rogers@xxxxxxxxxxxxx>
>
> This is the least-bad behaviour. It means that we signal the
> vblank event before it actually happens, but since we're disabling
> vblanks there's no guarantee that it will *ever* happen otherwise.
>
> This prevents GL applications which use WaitMSC from hanging
> indefinitely.
>
> Signed-off-by: Christopher James Halse Rogers <christopher.halse.rogers@xxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_irq.c | 23 +++++++++++++++++++++++
> 1 files changed, 23 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
> index 741457b..a1f12cb 100644
> --- a/drivers/gpu/drm/drm_irq.c
> +++ b/drivers/gpu/drm/drm_irq.c
> @@ -932,11 +932,34 @@ EXPORT_SYMBOL(drm_vblank_put);
>
> void drm_vblank_off(struct drm_device *dev, int crtc)
> {
> + struct drm_pending_vblank_event *e, *t;
> + struct timeval now;
> unsigned long irqflags;
> + unsigned int seq;
>
> spin_lock_irqsave(&dev->vbl_lock, irqflags);
> vblank_disable_and_save(dev, crtc);
> DRM_WAKEUP(&dev->vbl_queue[crtc]);
> +
> + /* Send any queued vblank events, lest the natives grow disquiet */
> + seq = drm_vblank_count_and_time(dev, crtc, &now);
> + list_for_each_entry_safe(e, t, &dev->vblank_event_list, base.link) {
> + if (e->pipe != crtc)
> + continue;
> + DRM_DEBUG("Sending premature vblank event on disable: \
> + wanted %d, current %d\n",
> + e->event.sequence, seq);
> +
> + e->event.sequence = seq;
> + e->event.tv_sec = now.tv_sec;
> + e->event.tv_usec = now.tv_usec;
> + drm_vblank_put(dev, e->pipe);
> + list_move_tail(&e->base.link, &e->base.file_priv->event_list);
> + wake_up_interruptible(&e->base.file_priv->event_wait);
> + trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
> + e->event.sequence);
> + }
> +
> spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
> }
> EXPORT_SYMBOL(drm_vblank_off);
Yeah, this matches what we do for the blocking waits, and it's probably
a good idea. Userspace can decide what to do with apps running against
a disabled CRTC.
Would be nice to share the code with drm_handle_vblank_events though
somehow. Looks like
e->event.sequence = seq;
e->event.tv_sec = now.tv_sec;
e->event.tv_usec = now.tv_usec;
drm_vblank_put(dev, e->pipe);
list_move_tail(&e->base.link, &e->base.file_priv->event_list);
wake_up_interruptible(&e->base.file_priv->event_wait);
trace_drm_vblank_event_delivered(e->base.pid, e->pipe,
e->event.sequence);
could be pulled out into a separate function for both to use.
--
Jesse Barnes, Intel Open Source Technology Center
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