[Intel-gfx] [PATCH] drm/i915: Shut down displays gracefully on reboot

[Chris Wilson]

On Sat, Aug 06, 2016 at 10:09:16AM +0200, Lukas Wunner wrote:
> On Wed, Aug 03, 2016 at 04:36:18PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Dell UP2414Q doesn't like it when we're driving it in MST mode, and then
> > reboot the machine. After reboot, the monitor is somehow confused and
> > refuses to do the payload allocation:
> >  [drm:drm_dp_mst_allocate_vcpi] initing vcpi for 282 8
> >  [drm:drm_dp_dpcd_write_payload] status not set after read payload table status 0
> > and thus we're left with a black screen until the monitor power is
> > toggled.
> > 
> > It seems that if we shut down things gracefully prior to rebooting, the
> > monitor doesn't get confused like this. So let's try to shut down all
> > the displays gracefully on reboot. The downside is that we will
> > introduce the reboot notifier to all the modesetl locks. So if there's
> > a locking bug around, we might not be able to reboot the machine
> > gracefully. sysrq reboot will still work though, as it will not
> > call the notifiers.
> 
> struct pci_driver has a ->shutdown hook which is currently not defined
> in i915_pci_driver. How about using that instead of reboot_notifier
> to avoid potential locking issues?

Interestingly that is also called prior to kexec. Doing a
i915_gem_suspend at that point I think would stop some of the GPU faults
we get across kexec.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre