[Intel-gfx] [PATCH] drm/i915/guc: Keep guc submission permanently engaged

[Chris Wilson]

Quoting Chris Wilson (2018-07-17 21:29:32)
> We make a decision at module load whether to use the GuC backend or not,
> but lose that setup across set-wedge. Currently, the guc doesn't
> override the engine->set_default_submission hook letting execlists sneak
> back in temporarily on unwedging leading to an unbalanced park/unpark.
> 
> v2: Remove comment about switching back temporarily to execlists on
> guc_submission_disable(). We currently only call disable on shutdown,
> and plan to also call disable before suspend and reset, in which case we
> will either restore guc submission or mark the driver as wedged, making
> the reset back to execlists pointless.
> v3: Move reset.prepare across

Fixes: 63572937cebf ("drm/i915/execlists: Flush pending preemption events during reset")
> Testcase: igt/drv_module_reload/basic-reload-inject
> Testcase: igt/gem_eio
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Michał Winiarski <michal.winiarski at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>

Pretty please? I know there are series incorporating it, but this should
help clear some regressing incompletes from the board.
-Chris