From 81ff52b705775433a955b2746d37b87bdc89a3d0 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: [PATCH] drm/i915/gt: Ratelimit display power w/a
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
---
drivers/gpu/drm/i915/gt/intel_gt_pm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
index bb57e3443a504..f36ce36dabeb3 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -88,8 +88,9 @@ static int __gt_park(struct intel_wakeref *wf)
/* Everything switched off, flush any residual interrupt just in case */
intel_synchronize_irq(i915);
+ /* 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();
--
2.30.2