DC states are disabled / re-enabled around each modeset, which may lead to a needless off->on->off toggling of the DC_off power well. This has some overhead as toggling DC states involves running a DMC firmware handler and also running a periodic firmware handler while DC states are enabled. The limit of when DC states have a benefit is at 30 FPS (using DC3co) and below 30 FPS (using DC5/6), where the firmware can actually disable clocks / power off power wells. Accordingly delay powering off the DC_off powerwell (which re-enables DC states) by 17 ms at the end of a modeset to avoid the above overhead at or above 60 FPS.
Signed-off-by: Imre Deak <[email protected]> --- drivers/gpu/drm/i915/display/intel_display.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c index dd52c689267f4..de77d130d6f9f 100644 --- a/drivers/gpu/drm/i915/display/intel_display.c +++ b/drivers/gpu/drm/i915/display/intel_display.c @@ -7148,7 +7148,11 @@ static void intel_atomic_commit_tail(struct intel_atomic_state *state) */ intel_uncore_arm_unclaimed_mmio_detection(&dev_priv->uncore); } - intel_display_power_put(dev_priv, POWER_DOMAIN_DC_OFF, wakeref); + /* + * Delay re-enabling DC states by 17 ms to avoid the off->on->off + * toggling overhead at and above 60 FPS. + */ + intel_display_power_put_async_delay(dev_priv, POWER_DOMAIN_DC_OFF, wakeref, 17); intel_runtime_pm_put(&dev_priv->runtime_pm, state->wakeref); /* -- 2.37.2
