On Mon, Nov 24, 2014 at 10:34:42AM +0100, Daniel Vetter wrote: > 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? Nah. But I was actually wondering why the unlocked flip complete prior to .update_plane() was supposedly necessary at all. But yeah the missing wake_up before that commit explains it. I'll see about respinning the patch with the flip complete moved back after the reset. I guess I could actually move it occur even after .update_plane() now. -- Ville Syrjälä Intel OTC _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
