[Intel-gfx] [PATCH 7/7] drm/i915/uc: Don't forget to prepare GuC for the reset

[Chris Wilson]

Quoting Michal Wajdeczko (2019-05-17 17:54:53)
> On Fri, 17 May 2019 18:27:44 +0200, Chris Wilson  
> <chris at chris-wilson.co.uk> wrote:
> 
> > Quoting Michal Wajdeczko (2019-05-17 17:22:27)
> >> When we reset engines using ALL_ENGINES mask, we will do
> >> full GPU reset and GuC will be also affected. Let GuC be
> >> prepared for upcoming reset.
> >>
> >> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> >> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> >> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> >> ---
> >>  drivers/gpu/drm/i915/gt/intel_reset.c | 4 ++++
> >>  1 file changed, 4 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c  
> >> b/drivers/gpu/drm/i915/gt/intel_reset.c
> >> index 464369bc55ad..ca6e40b6b4e2 100644
> >> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> >> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> >> @@ -564,6 +564,10 @@ static int gen8_reset_engines(struct  
> >> drm_i915_private *i915,
> >>                  */
> >>         }
> >>
> >> +       /* We are about to do full GPU reset, don't forget about GuC */
> >> +       if (engine_mask == ALL_ENGINES)
> >> +               intel_uc_reset_prepare(i915);
> >
> > Eh, this is done in reset_prepare already. The only other path to call
> > intel_gpu_reset() directly is along sanitization, which should also have
> > already sanitized the guc as well. No?
> 
> There is igt_atomic_reset selftest which does not call reset_prepare.
> And since we lost GuC in gen6_reset_engines due to GEN6_GRDOM_FULL,
> our later graceful goodbye with GuC was not working.

Ok, the intent there was to avoid letting any sleeps slip into the
device reset itself (should we need to put it inside a heavy hammer like
stop_machine() to serialise it with direct user access to the hw). I
think it is fair to put that under reset_prepare / reset_finish. Would
also mean moving it out of selftest_hangcheck and into selftest_reset.
-Chris