From 05e76fe38fa797c12507ad26719797b3fe2a1308 Mon Sep 17 00:00:00 2001
From: Michael Wright <michaelwr@google.com>
Date: Thu, 20 Jul 2017 18:18:33 +0100
Subject: [PATCH] Add config to force display to transition to off after doze

Some display hardware can't do the transition from doze display states
to the on display state cleanly, so in order to hide any janky-ness of
the transition we force the display off and cover the screen with a
black surface. This lets us keep the screen black until SystemUI and the
display are both ready.

Bug: 63531607
Test: manual
Change-Id: I66bd483e5f01e1dbd5069465aa122828af5f1903
---
 core/java/android/view/Display.java           |  9 +++++
 core/res/res/values/config.xml                |  5 +++
 core/res/res/values/symbols.xml               |  1 +
 .../display/DisplayPowerController.java       | 36 +++++++++++++++++--
 4 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/core/java/android/view/Display.java b/core/java/android/view/Display.java
index 7346a215ed8ea..263d3ff423c5b 100644
--- a/core/java/android/view/Display.java
+++ b/core/java/android/view/Display.java
@@ -1132,6 +1132,15 @@ public final class Display {
         return state == STATE_OFF || state == STATE_DOZE_SUSPEND;
     }
 
+    /**
+     * Returns true if the display may be in a reduced operating mode while in the
+     * specified display power state.
+     * @hide
+     */
+    public static boolean isDozeState(int state) {
+        return state == STATE_DOZE || state == STATE_DOZE_SUSPEND;
+    }
+
     /**
      * A mode supported by a given display.
      *
diff --git a/core/res/res/values/config.xml b/core/res/res/values/config.xml
index 60db8ca5633cc..f817ab39bf6c1 100644
--- a/core/res/res/values/config.xml
+++ b/core/res/res/values/config.xml
@@ -1862,6 +1862,11 @@
          states. -->
     <bool name="config_dozeAlwaysOnDisplayAvailable">false</bool>
 
+    <!-- Whether the display hardware requires we go to the off state before transitioning
+         out of any doze states. -->
+    <bool name="config_displayTransitionOffAfterDoze">false</bool>
+
+
     <!-- Power Management: Specifies whether to decouple the auto-suspend state of the
          device from the display on/off state.
 
diff --git a/core/res/res/values/symbols.xml b/core/res/res/values/symbols.xml
index c49763fc63e7b..7670c7ba4086b 100644
--- a/core/res/res/values/symbols.xml
+++ b/core/res/res/values/symbols.xml
@@ -3064,6 +3064,7 @@
   <java-symbol type="bool" name="config_handleVolumeKeysInWindowManager" />
   <java-symbol type="integer" name="config_inCallNotificationVolumeRelative" />
   <java-symbol type="bool" name="config_dozeAlwaysOnDisplayAvailable" />
+  <java-symbol type="bool" name="config_displayTransitionOffAfterDoze" />
   <java-symbol type="integer" name="config_storageManagerDaystoRetainDefault" />
   <java-symbol type="string" name="config_headlineFontFamily" />
   <java-symbol type="string" name="config_headlineFontFamilyLight" />
diff --git a/services/core/java/com/android/server/display/DisplayPowerController.java b/services/core/java/com/android/server/display/DisplayPowerController.java
index e82724db27f75..cbd02acd7d86d 100644
--- a/services/core/java/com/android/server/display/DisplayPowerController.java
+++ b/services/core/java/com/android/server/display/DisplayPowerController.java
@@ -165,6 +165,12 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
     // a stylish color fade animation instead.
     private boolean mColorFadeFadesConfig;
 
+    // True if we need to transition to the off state when coming out of a doze state.
+    // Some display hardware will show artifacts (flickers, etc) when transitioning from a doze
+    // to a fully on state. In order to hide these, we first transition to off to let the system
+    // animate the screen on as it normally would, which is a much smoother experience.
+    private boolean mTransitionOffAfterDozeConfig;
+
     // The pending power request.
     // Initially null until the first call to requestPowerState.
     // Guarded by mLock.
@@ -410,6 +416,9 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
         mColorFadeFadesConfig = resources.getBoolean(
                 com.android.internal.R.bool.config_animateScreenLights);
 
+        mTransitionOffAfterDozeConfig = resources.getBoolean(
+                com.android.internal.R.bool.config_displayTransitionOffAfterDoze);
+
         if (!DEBUG_PRETEND_PROXIMITY_SENSOR_ABSENT) {
             mProximitySensor = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);
             if (mProximitySensor != null) {
@@ -877,6 +886,10 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
     }
 
     private boolean setScreenState(int state) {
+        return setScreenState(state, false /*force*/);
+    }
+
+    private boolean setScreenState(int state, boolean force) {
         final boolean isOff = (state == Display.STATE_OFF);
         if (mPowerState.getScreenState() != state) {
 
@@ -887,9 +900,17 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
                     mReportedScreenStateToPolicy = REPORTED_TO_POLICY_SCREEN_TURNING_OFF;
                     blockScreenOff();
                     mWindowManagerPolicy.screenTurningOff(mPendingScreenOffUnblocker);
-                    return false;
+                    if (force) {
+                        // If we're forcing the power state transition then immediately
+                        // unblock the screen off event. This keeps the lifecycle consistent,
+                        // so WindowManagerPolicy will always see screenTurningOff before
+                        // screenTurnedOff, but we don't actually block on them for the state
+                        // change.
+                        unblockScreenOff();
+                    } else {
+                        return false;
+                    }
                 } else if (mPendingScreenOffUnblocker != null) {
-
                     // Abort doing the state change until screen off is unblocked.
                     return false;
                 }
@@ -968,6 +989,17 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
             mPendingScreenOff = false;
         }
 
+        if (mTransitionOffAfterDozeConfig &&
+                Display.isDozeState(mPowerState.getScreenState())
+                && !Display.isDozeState(target)) {
+            setScreenState(Display.STATE_OFF, true /*force*/);
+            // Skip the screen off animation and add a black surface to hide the
+            // contents of the screen. This will also trigger another power state update so that we
+            // end up converging on the target state.
+            mColorFadeOffAnimator.end();
+            return;
+        }
+
         // If we were in the process of turning off the screen but didn't quite
         // finish.  Then finish up now to prevent a jarring transition back
         // to screen on if we skipped blocking screen on as usual.