On Fri, Nov 21, 2014 at 11:10:31PM +0200, Ville Syrjälä wrote:
> On Fri, Nov 21, 2014 at 09:49:21PM +0100, Daniel Vetter wrote:
> > On Fri, Nov 21, 2014 at 09:54:29PM +0200, ville.syrjala@xxxxxxxxxxxxxxx wrote:
> > > +
> > > + /*
> > > + * Flips in the rings will be nuked by the reset,
> > > + * so complete all pending flips so that user space
> > > + * will get its events and not get stuck.
> > > + *
> > > + * Old platforms will also reset the display, so we
> > > + * need to grab the modeset locks around the reset.
> > > + * But in order to do that we must let any pending
> > > + * page flip wait complete since the waiters may be
> > > + * holding some modeset locks.
> > > + */
> > > + intel_complete_page_flips(dev);
> >
> > Is this really required? We complete them afterwards, and all the pageflip
> > waiters I've found do check for gpu hangs and abort the pageflip wait.
> > That's already required since the mmio flip might go missing, and thus far
> > we've only completed the flip _after_ having reset the gpu and gem state
> > (and grabbed dev->struct_mutex).
>
> Hmm. Yeah, just waking them up ought to be sufficient to dislodge
> things. And we already do that before scheduling the error work, but
> after setting the reset_in_progress flag, which is very much critical
> here. So I guess I could just move the complete pending flips bit to
> intel_finish_reset().
>
> But then I do wonder a bit why I originally needed to add the unlocked
> page flip complete before the locked .update_plane() call. Did we miss
> a wakeup somewhere or did we not abort pending flip waits on reset?
gpu hang vs. pending flip deadlocks should have been fixed with
commit 17e1df07df0fbc77696a1e1b6ccf9f2e5af70e40
Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
Date: Sun Sep 8 21:57:13 2013 +0200
drm/i915: fix wait_for_pending_flips vs gpu hang deadlock
Maybe it's been broken meanwhile but it should have worked since quite a
while. Or are these gen3/4 reset patches really this old?
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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