Commit 93e16472 authored Aug 21, 2019 by Santos Cordon

Hold Display suspend blocker until doze starts

When transitioning to DOZE, there is a race condition between the
release of the display suspend blocker and calling startDream. This
creates a gap where the device can suspend before the dream actually
starts.  In practice, this can cause gestures, which are nitialized
from the Dream Service, to not function until something else
temporarily wakes up the device enough for the CPU to run a few
cycles.

This change delays the release of the display suspend blocker if
there is a pending recalculation of the sleep/doze state.

Bug: 138828701
Test: Manual testing - was 1 in 5 chance of reproing.  Tested up to
0 out of 50 after the fix.
Test: atest PowerManagerServiceTest

Change-Id: Ic6df469972dc5765a8c4507404d1dc33f13ec0c3

parent 36da9bb9

services/core/java/com/android/server/power/PowerManagerService.java

+11 −0

Original line number	Diff line number	Diff line
		@@ -2735,6 +2735,17 @@ public final class PowerManagerService extends SystemService
		if (mScreenBrightnessBoostInProgress) {
		return true;
		}

		// Because summoning the sandman is asyncronous, there is a time-gap where
		// we release the display suspend blocker before the dream service acquires
		// their own wakelock. Within this gap, we can end up suspending before
		// dream service has a chance to start. To avoid this, we check if we want
		// to doze and the sandman is scheduled and if so, keep the display on until
		// that has passed.
		if (mWakefulness == WAKEFULNESS_DOZING && mSandmanScheduled) {
		return true;
		}

		// Let the system suspend if the screen is off or dozing.
		return false;
		}