[Intel-gfx] [PATCH 5/5] drm/i915: Only sanitize GEM from late suspend

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-05-30 17:56:20)
> 
> On 29/05/2018 14:29, Chris Wilson wrote:
> > During testing we encounter a conflict between SUSPEND_TEST_DEVICES and
> > disabling reset (gem_eio/suspend). This results in the device continuing
> > on without being reset, but since it has gone through HW sanitization to
> 
> Has some test been failing because of this and since when? gem_eio/suspend?

Yes. It will fail in the future because we'll remove all mmio from the
process_csb(); it fails right now because we lose track of what
interrupts we process across the suspend and may double handle CSB events.
E.g. https://bugs.freedesktop.org/show_bug.cgi?id=106702
 
> > account for the suspend/resume cycle, we have to assume the device has
> > been reset to its defaults. A simple way around this is to skip the
> > sanitize phase for SUSPEND_TEST_DEVICES by moving it to suspend-late.
> 
> So suspend_late is not called when suspending via SUSPEND_TEST_DEVICES? 
> Sounds weird to me that core allows a "half-way" suspend mode. But I am 
> not familiar with that code so don't know.

Yes, weird is one way to describe it.
 
> Either way, if we skip it, that only skips the reset which is skipped 
> anyway in gem_eio/suspend so I did not figure out the difference.

We then also skip the call to reset->reset which we need after a real
resume (when the device is powered up) and/or after the reset in
sanitization. It's fiddly.
-Chris