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@xxxxxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
---
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 bb57e3443a50..f36ce36dabeb 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();
--
2.24.1
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