From d39da686c2f3b8518b6933951d53891aa83227d6 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 18 Dec 2019 09:35:04 +0000
Subject: drm/i915/gt: Ratelimit display power w/a
Git-commit: d39da686c2f3b8518b6933951d53891aa83227d6
Patch-mainline: v5.5-rc4
References: bsc#1152489

For very light workloads that frequently park, acquiring the display
power well (required to prevent the dmc from trashing the system) takes
longer than the execution. A good example is the igt_coherency selftest,
which is slowed down by an order of magnitude in the worst case with
powerwell cycling. To prevent frequent cycling, while keeping our fast
soft-rc6, use a timer to delay release of the display powerwell.

Fixes: 311770173fac ("drm/i915/gt: Schedule request retirement when timeline idles")
References: https://gitlab.freedesktop.org/drm/intel/issues/848
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191218093504.3477048-1-chris@chris-wilson.co.uk
(cherry picked from commit 81ff52b705775433a955b2746d37b87bdc89a3d0)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/i915/gt/intel_gt_pm.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -102,8 +102,9 @@ static int __gt_park(struct intel_wakere
 		intel_uncore_forcewake_put(&i915->uncore, FORCEWAKE_ALL);
 	}
 
+	/* Defer dropping the display power well for 100ms, it's slow! */
 	GEM_BUG_ON(!wakeref);
-	intel_display_power_put(i915, POWER_DOMAIN_GT_IRQ, wakeref);
+	intel_display_power_put_async(i915, POWER_DOMAIN_GT_IRQ, wakeref);
 
 	i915_globals_park();