[Intel-gfx] [PATCH 6/7] drm/i915/uc: Stop GuC submission during reset prepare

[Chris Wilson]

Quoting Michal Wajdeczko (2019-05-17 17:22:26)
> +void intel_guc_submission_stop(struct intel_guc *guc)
> +{
> +       struct drm_i915_private *i915 = guc_to_i915(guc);
> +
> +       GEM_BUG_ON(i915->gt.awake); /* GT should be parked first */

How is this true for reset? Note, it's an unlocked read, so READ_ONCE()
or something along GEM_BUG_ON(intel_wakeref_active(&i915->gt.wakeref))

Though I think this is wrong!

i915_reset or i915_gem_set_wedged
 -> reset_prepare
    -> intel_uc_reset_prepare
       -> intel_guc_submission_stop

No locks, no parking. So how does this survive selftests? :(
-Chris