Merge cherrypicks of [17180656, 17180657, 17180658, 17180659] into sc-d2-release.

Change-Id: I0d4485f0fd62aad0f110b0d22b22d07a0247e4bd

9 files changed, 348 insertions, 28 deletions

diff --git a/services/core/java/com/android/server/display/BrightnessTracker.java b/services/core/java/com/android/server/display/BrightnessTracker.java
index 2c2a2bf24cfd..17215e5ae4ad 100644
--- a/services/core/java/com/android/server/display/BrightnessTracker.java
+++ b/services/core/java/com/android/server/display/BrightnessTracker.java
@@ -131,6 +131,7 @@ public class BrightnessTracker {
     private static final int MSG_STOP_SENSOR_LISTENER = 2;
     private static final int MSG_START_SENSOR_LISTENER = 3;
     private static final int MSG_BRIGHTNESS_CONFIG_CHANGED = 4;
+    private static final int MSG_SENSOR_CHANGED = 5;
 
     private static final SimpleDateFormat FORMAT = new SimpleDateFormat("MM-dd HH:mm:ss.SSS");
 
@@ -158,6 +159,7 @@ public class BrightnessTracker {
     // These members should only be accessed on the mBgHandler thread.
     private BroadcastReceiver mBroadcastReceiver;
     private SensorListener mSensorListener;
+    private Sensor mLightSensor;
     private SettingsObserver mSettingsObserver;
     private DisplayListener mDisplayListener;
     private boolean mSensorRegistered;
@@ -327,6 +329,14 @@ public class BrightnessTracker {
         m.sendToTarget();
     }
 
+    /**
+     * Updates the light sensor to use.
+     */
+    public void setLightSensor(Sensor lightSensor) {
+        mBgHandler.obtainMessage(MSG_SENSOR_CHANGED, 0 /*unused*/, 0/*unused*/, lightSensor)
+                .sendToTarget();
+    }
+
     private void handleBrightnessChanged(float brightness, boolean userInitiated,
             float powerBrightnessFactor, boolean isUserSetBrightness,
             boolean isDefaultBrightnessConfig, long timestamp, String uniqueDisplayId) {
@@ -428,13 +438,28 @@ public class BrightnessTracker {
         }
     }
 
+    private void handleSensorChanged(Sensor lightSensor) {
+        if (mLightSensor != lightSensor) {
+            mLightSensor = lightSensor;
+            stopSensorListener();
+            synchronized (mDataCollectionLock) {
+                mLastSensorReadings.clear();
+            }
+            // Attempt to restart the sensor listener. It will check to see if it should be running
+            // so there is no need to also check here.
+            startSensorListener();
+        }
+    }
+
     private void startSensorListener() {
         if (!mSensorRegistered
+                && mLightSensor != null
+                && mAmbientBrightnessStatsTracker != null
                 && mInjector.isInteractive(mContext)
                 && mInjector.isBrightnessModeAutomatic(mContentResolver)) {
             mAmbientBrightnessStatsTracker.start();
             mSensorRegistered = true;
-            mInjector.registerSensorListener(mContext, mSensorListener,
+            mInjector.registerSensorListener(mContext, mSensorListener, mLightSensor,
                     mInjector.getBackgroundHandler());
         }
     }
@@ -736,6 +761,7 @@ public class BrightnessTracker {
         pw.println("BrightnessTracker state:");
         synchronized (mDataCollectionLock) {
             pw.println("  mStarted=" + mStarted);
+            pw.println("  mLightSensor=" + mLightSensor);
             pw.println("  mLastBatteryLevel=" + mLastBatteryLevel);
             pw.println("  mLastBrightness=" + mLastBrightness);
             pw.println("  mLastSensorReadings.size=" + mLastSensorReadings.size());
@@ -1017,6 +1043,9 @@ public class BrightnessTracker {
                         disableColorSampling();
                     }
                     break;
+                case MSG_SENSOR_CHANGED:
+                    handleSensorChanged((Sensor) msg.obj);
+                    break;
 
             }
         }
@@ -1045,9 +1074,8 @@ public class BrightnessTracker {
     @VisibleForTesting
     static class Injector {
         public void registerSensorListener(Context context,
-                SensorEventListener sensorListener, Handler handler) {
+                SensorEventListener sensorListener, Sensor lightSensor, Handler handler) {
             SensorManager sensorManager = context.getSystemService(SensorManager.class);
-            Sensor lightSensor = sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
             sensorManager.registerListener(sensorListener,
                     lightSensor, SensorManager.SENSOR_DELAY_NORMAL, handler);
         }
diff --git a/services/core/java/com/android/server/display/BrightnessUtils.java b/services/core/java/com/android/server/display/BrightnessUtils.java
new file mode 100644
index 000000000000..84fa0cccbd10
--- /dev/null
+++ b/services/core/java/com/android/server/display/BrightnessUtils.java
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.display;
+
+import android.util.MathUtils;
+
+/**
+ * Utility class providing functions to convert between linear and perceptual gamma space.
+ *
+ * Internally, this implements the Hybrid Log Gamma electro-optical transfer function, which is a
+ * slight improvement to the typical gamma transfer function for displays whose max brightness
+ * exceeds the 120 nit reference point, but doesn't set a specific reference brightness like the PQ
+ * function does.
+ *
+ * Note that this transfer function is only valid if the display's backlight value is a linear
+ * control. If it's calibrated to be something non-linear, then a different transfer function
+ * should be used.
+ *
+ * Note: This code is based on the same class in the com.android.settingslib.display package.
+ */
+public class BrightnessUtils {
+
+    // Hybrid Log Gamma constant values
+    private static final float R = 0.5f;
+    private static final float A = 0.17883277f;
+    private static final float B = 0.28466892f;
+    private static final float C = 0.55991073f;
+
+    /**
+     * A function for converting from the gamma space into the linear space.
+     *
+     * @param val The value in the gamma space [0 .. 1.0]
+     * @return The corresponding value in the linear space [0 .. 1.0].
+     */
+    public static final float convertGammaToLinear(float val) {
+        final float ret;
+        if (val <= R) {
+            ret = MathUtils.sq(val / R);
+        } else {
+            ret = MathUtils.exp((val - C) / A) + B;
+        }
+
+        // HLG is normalized to the range [0, 12], ensure that value is within that range,
+        // it shouldn't be out of bounds.
+        final float normalizedRet = MathUtils.constrain(ret, 0, 12);
+
+        // Re-normalize to the range [0, 1]
+        // in order to derive the correct setting value.
+        return normalizedRet / 12;
+    }
+
+    /**
+     * A function for converting from the linear space into the gamma space.
+     *
+     * @param val The value in linear space [0 .. 1.0]
+     * @return The corresponding value in gamma space [0 .. 1.0]
+     */
+    public static final float convertLinearToGamma(float val) {
+        // For some reason, HLG normalizes to the range [0, 12] rather than [0, 1]
+        final float normalizedVal = val * 12;
+        final float ret;
+        if (normalizedVal <= 1f) {
+            ret = MathUtils.sqrt(normalizedVal) * R;
+        } else {
+            ret = A * MathUtils.log(normalizedVal - B) + C;
+        }
+        return ret;
+    }
+}
diff --git a/services/core/java/com/android/server/display/DisplayDeviceConfig.java b/services/core/java/com/android/server/display/DisplayDeviceConfig.java
index 2ae5cbbbf24b..255494f98667 100644
--- a/services/core/java/com/android/server/display/DisplayDeviceConfig.java
+++ b/services/core/java/com/android/server/display/DisplayDeviceConfig.java
@@ -31,6 +31,7 @@ import android.view.DisplayAddress;
 
 import com.android.internal.R;
 import com.android.internal.display.BrightnessSynchronizer;
+import com.android.server.display.config.BrightnessThresholds;
 import com.android.server.display.config.DisplayConfiguration;
 import com.android.server.display.config.DisplayQuirks;
 import com.android.server.display.config.HbmTiming;
@@ -40,6 +41,7 @@ import com.android.server.display.config.Point;
 import com.android.server.display.config.RefreshRateRange;
 import com.android.server.display.config.SensorDetails;
 import com.android.server.display.config.ThermalStatus;
+import com.android.server.display.config.Thresholds;
 import com.android.server.display.config.XmlParser;
 
 import org.xmlpull.v1.XmlPullParserException;
@@ -115,6 +117,10 @@ public class DisplayDeviceConfig {
     private float mBrightnessRampFastIncrease = Float.NaN;
     private float mBrightnessRampSlowDecrease = Float.NaN;
     private float mBrightnessRampSlowIncrease = Float.NaN;
+    private float mScreenBrighteningMinThreshold = 0.0f;     // Retain behaviour as though there is
+    private float mScreenDarkeningMinThreshold = 0.0f;       // no minimum threshold for change in
+    private float mAmbientLuxBrighteningMinThreshold = 0.0f; // screen brightness or ambient
+    private float mAmbientLuxDarkeningMinThreshold = 0.0f;   // brightness.
     private Spline mBrightnessToBacklightSpline;
     private Spline mBacklightToBrightnessSpline;
     private Spline mBacklightToNitsSpline;
@@ -282,6 +288,22 @@ public class DisplayDeviceConfig {
         return mBrightnessRampSlowIncrease;
     }
 
+    public float getScreenBrighteningMinThreshold() {
+        return mScreenBrighteningMinThreshold;
+    }
+
+    public float getScreenDarkeningMinThreshold() {
+        return mScreenDarkeningMinThreshold;
+    }
+
+    public float getAmbientLuxBrighteningMinThreshold() {
+        return mAmbientLuxBrighteningMinThreshold;
+    }
+
+    public float getAmbientLuxDarkeningMinThreshold() {
+        return mAmbientLuxDarkeningMinThreshold;
+    }
+
     SensorData getAmbientLightSensor() {
         return mAmbientLightSensor;
     }
@@ -337,6 +359,10 @@ public class DisplayDeviceConfig {
                 + ", mBrightnessRampFastIncrease=" + mBrightnessRampFastIncrease
                 + ", mBrightnessRampSlowDecrease=" + mBrightnessRampSlowDecrease
                 + ", mBrightnessRampSlowIncrease=" + mBrightnessRampSlowIncrease
+                + ", mScreenDarkeningMinThreshold=" + mScreenDarkeningMinThreshold
+                + ", mScreenBrighteningMinThreshold=" + mScreenBrighteningMinThreshold
+                + ", mAmbientLuxDarkeningMinThreshold=" + mAmbientLuxDarkeningMinThreshold
+                + ", mAmbientLuxBrighteningMinThreshold=" + mAmbientLuxBrighteningMinThreshold
                 + ", mAmbientLightSensor=" + mAmbientLightSensor
                 + ", mProximitySensor=" + mProximitySensor
                 + ", mRefreshRateLimitations= " + Arrays.toString(mRefreshRateLimitations.toArray())
@@ -392,6 +418,7 @@ public class DisplayDeviceConfig {
                 loadBrightnessRamps(config);
                 loadAmbientLightSensorFromDdc(config);
                 loadProxSensorFromDdc(config);
+                loadBrightnessChangeThresholds(config);
             } else {
                 Slog.w(TAG, "DisplayDeviceConfig file is null");
             }
@@ -746,6 +773,45 @@ public class DisplayDeviceConfig {
         }
     }
 
+    private void loadBrightnessChangeThresholds(DisplayConfiguration config) {
+        Thresholds displayBrightnessThresholds = config.getDisplayBrightnessChangeThresholds();
+        Thresholds ambientBrightnessThresholds = config.getAmbientBrightnessChangeThresholds();
+
+        if (displayBrightnessThresholds != null) {
+            BrightnessThresholds brighteningScreen =
+                    displayBrightnessThresholds.getBrighteningThresholds();
+            BrightnessThresholds darkeningScreen =
+                    displayBrightnessThresholds.getDarkeningThresholds();
+
+            final BigDecimal screenBrighteningThreshold = brighteningScreen.getMinimum();
+            final BigDecimal screenDarkeningThreshold = darkeningScreen.getMinimum();
+
+            if (screenBrighteningThreshold != null) {
+                mScreenBrighteningMinThreshold = screenBrighteningThreshold.floatValue();
+            }
+            if (screenDarkeningThreshold != null) {
+                mScreenDarkeningMinThreshold = screenDarkeningThreshold.floatValue();
+            }
+        }
+
+        if (ambientBrightnessThresholds != null) {
+            BrightnessThresholds brighteningAmbientLux =
+                    ambientBrightnessThresholds.getBrighteningThresholds();
+            BrightnessThresholds darkeningAmbientLux =
+                    ambientBrightnessThresholds.getDarkeningThresholds();
+
+            final BigDecimal ambientBrighteningThreshold = brighteningAmbientLux.getMinimum();
+            final BigDecimal ambientDarkeningThreshold =  darkeningAmbientLux.getMinimum();
+
+            if (ambientBrighteningThreshold != null) {
+                mAmbientLuxBrighteningMinThreshold = ambientBrighteningThreshold.floatValue();
+            }
+            if (ambientDarkeningThreshold != null) {
+                mAmbientLuxDarkeningMinThreshold = ambientDarkeningThreshold.floatValue();
+            }
+        }
+    }
+
     private @PowerManager.ThermalStatus int convertThermalStatus(ThermalStatus value) {
         if (value == null) {
             return PowerManager.THERMAL_STATUS_NONE;
diff --git a/services/core/java/com/android/server/display/DisplayPowerController.java b/services/core/java/com/android/server/display/DisplayPowerController.java
index 22dd2c05c157..77c1fc031598 100644
--- a/services/core/java/com/android/server/display/DisplayPowerController.java
+++ b/services/core/java/com/android/server/display/DisplayPowerController.java
@@ -795,7 +795,6 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
     private void loadFromDisplayDeviceConfig(IBinder token, DisplayDeviceInfo info) {
         // All properties that depend on the associated DisplayDevice and the DDC must be
         // updated here.
-        loadAmbientLightSensor();
         loadBrightnessRampRates();
         loadProximitySensor();
         loadNitsRange(mContext.getResources());
@@ -880,9 +879,14 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
                     com.android.internal.R.array.config_ambientDarkeningThresholds);
             int[] ambientThresholdLevels = resources.getIntArray(
                     com.android.internal.R.array.config_ambientThresholdLevels);
+            float ambientDarkeningMinThreshold =
+                    mDisplayDeviceConfig.getAmbientLuxDarkeningMinThreshold();
+            float ambientBrighteningMinThreshold =
+                    mDisplayDeviceConfig.getAmbientLuxBrighteningMinThreshold();
             HysteresisLevels ambientBrightnessThresholds = new HysteresisLevels(
                     ambientBrighteningThresholds, ambientDarkeningThresholds,
-                    ambientThresholdLevels);
+                    ambientThresholdLevels, ambientDarkeningMinThreshold,
+                    ambientBrighteningMinThreshold);
 
             int[] screenBrighteningThresholds = resources.getIntArray(
                     com.android.internal.R.array.config_screenBrighteningThresholds);
@@ -890,8 +894,13 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
                     com.android.internal.R.array.config_screenDarkeningThresholds);
             int[] screenThresholdLevels = resources.getIntArray(
                     com.android.internal.R.array.config_screenThresholdLevels);
+            float screenDarkeningMinThreshold =
+                    mDisplayDeviceConfig.getScreenDarkeningMinThreshold();
+            float screenBrighteningMinThreshold =
+                    mDisplayDeviceConfig.getScreenBrighteningMinThreshold();
             HysteresisLevels screenBrightnessThresholds = new HysteresisLevels(
-                    screenBrighteningThresholds, screenDarkeningThresholds, screenThresholdLevels);
+                    screenBrighteningThresholds, screenDarkeningThresholds, screenThresholdLevels,
+                    screenDarkeningMinThreshold, screenBrighteningMinThreshold);
 
             long brighteningLightDebounce = resources.getInteger(
                     com.android.internal.R.integer.config_autoBrightnessBrighteningLightDebounce);
@@ -915,6 +924,9 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
             }
 
             loadAmbientLightSensor();
+            if (mBrightnessTracker != null) {
+                mBrightnessTracker.setLightSensor(mLightSensor);
+            }
 
             if (mAutomaticBrightnessController != null) {
                 mAutomaticBrightnessController.stop();
diff --git a/services/core/java/com/android/server/display/HysteresisLevels.java b/services/core/java/com/android/server/display/HysteresisLevels.java
index 2b565698ff8c..7a932ce6d7cf 100644
--- a/services/core/java/com/android/server/display/HysteresisLevels.java
+++ b/services/core/java/com/android/server/display/HysteresisLevels.java
@@ -30,17 +30,13 @@ import java.util.Arrays;
 public class HysteresisLevels {
     private static final String TAG = "HysteresisLevels";
 
-    // Default hysteresis constraints for brightening or darkening.
-    // The recent value must have changed by at least this fraction relative to the
-    // current value before a change will be considered.
-    private static final float DEFAULT_BRIGHTENING_HYSTERESIS = 0.10f;
-    private static final float DEFAULT_DARKENING_HYSTERESIS = 0.20f;
-
     private static final boolean DEBUG = false;
 
     private final float[] mBrighteningThresholds;
     private final float[] mDarkeningThresholds;
     private final float[] mThresholdLevels;
+    private final float mMinDarkening;
+    private final float mMinBrightening;
 
     /**
      * Creates a {@code HysteresisLevels} object with the given equal-length
@@ -48,9 +44,12 @@ public class HysteresisLevels {
      * @param brighteningThresholds an array of brightening hysteresis constraint constants.
      * @param darkeningThresholds an array of darkening hysteresis constraint constants.
      * @param thresholdLevels a monotonically increasing array of threshold levels.
+     * @param minBrighteningThreshold the minimum value for which the brightening value needs to
+     *                                return.
+     * @param minDarkeningThreshold the minimum value for which the darkening value needs to return.
     */
     HysteresisLevels(int[] brighteningThresholds, int[] darkeningThresholds,
-            int[] thresholdLevels) {
+            int[] thresholdLevels, float minDarkeningThreshold, float minBrighteningThreshold) {
         if (brighteningThresholds.length != darkeningThresholds.length
                 || darkeningThresholds.length != thresholdLevels.length + 1) {
             throw new IllegalArgumentException("Mismatch between hysteresis array lengths.");
@@ -58,6 +57,8 @@ public class HysteresisLevels {
         mBrighteningThresholds = setArrayFormat(brighteningThresholds, 1000.0f);
         mDarkeningThresholds = setArrayFormat(darkeningThresholds, 1000.0f);
         mThresholdLevels = setArrayFormat(thresholdLevels, 1.0f);
+        mMinDarkening = minDarkeningThreshold;
+        mMinBrightening = minBrighteningThreshold;
     }
 
     /**
@@ -65,11 +66,13 @@ public class HysteresisLevels {
      */
     public float getBrighteningThreshold(float value) {
         final float brightConstant = getReferenceLevel(value, mBrighteningThresholds);
-        final float brightThreshold = value * (1.0f + brightConstant);
+        float brightThreshold = value * (1.0f + brightConstant);
         if (DEBUG) {
             Slog.d(TAG, "bright hysteresis constant=" + brightConstant + ", threshold="
                     + brightThreshold + ", value=" + value);
         }
+
+        brightThreshold = Math.max(brightThreshold, value + mMinBrightening);
         return brightThreshold;
     }
 
@@ -78,12 +81,13 @@ public class HysteresisLevels {
      */
     public float getDarkeningThreshold(float value) {
         final float darkConstant = getReferenceLevel(value, mDarkeningThresholds);
-        final float darkThreshold = value * (1.0f - darkConstant);
+        float darkThreshold = value * (1.0f - darkConstant);
         if (DEBUG) {
             Slog.d(TAG, "dark hysteresis constant=: " + darkConstant + ", threshold="
                     + darkThreshold + ", value=" + value);
         }
-        return darkThreshold;
+        darkThreshold = Math.min(darkThreshold, value - mMinDarkening);
+        return Math.max(darkThreshold, 0.0f);
     }
 
     /**
diff --git a/services/core/java/com/android/server/display/RampAnimator.java b/services/core/java/com/android/server/display/RampAnimator.java
index ed3b15fb2661..d8672fc07619 100644
--- a/services/core/java/com/android/server/display/RampAnimator.java
+++ b/services/core/java/com/android/server/display/RampAnimator.java
@@ -23,6 +23,8 @@ import android.view.Choreographer;
 /**
  * A custom animator that progressively updates a property value at
  * a given variable rate until it reaches a particular target value.
+ * The ramping at the given rate is done in the perceptual space using
+ * the HLG transfer functions.
  */
 class RampAnimator<T> {
     private final T mObject;
@@ -57,7 +59,9 @@ class RampAnimator<T> {
      * @param rate The convergence rate in units per second, or 0 to set the value immediately.
      * @return True if the target differs from the previous target.
      */
-    public boolean animateTo(float target, float rate) {
+    public boolean animateTo(float targetLinear, float rate) {
+        // Convert the target from the linear into the HLG space.
+        final float target = BrightnessUtils.convertLinearToGamma(targetLinear);
 
         // Immediately jump to the target the first time.
         if (mFirstTime || rate <= 0) {
@@ -66,7 +70,7 @@ class RampAnimator<T> {
                 mRate = 0;
                 mTargetValue = target;
                 mCurrentValue = target;
-                mProperty.setValue(mObject, target);
+                setPropertyValue(target);
                 if (mAnimating) {
                     mAnimating = false;
                     cancelAnimationCallback();
@@ -121,6 +125,15 @@ class RampAnimator<T> {
         mListener = listener;
     }
 
+    /**
+     * Sets the brightness property by converting the given value from HLG space
+     * into linear space.
+     */
+    private void setPropertyValue(float val) {
+        final float linearVal = BrightnessUtils.convertGammaToLinear(val);
+        mProperty.setValue(mObject, linearVal);
+    }
+
     private void postAnimationCallback() {
         mChoreographer.postCallback(Choreographer.CALLBACK_ANIMATION, mAnimationCallback, null);
     }
@@ -156,7 +169,7 @@ class RampAnimator<T> {
             final float oldCurrentValue = mCurrentValue;
             mCurrentValue = mAnimatedValue;
             if (oldCurrentValue != mCurrentValue) {
-                mProperty.setValue(mObject, mCurrentValue);
+                setPropertyValue(mCurrentValue);
             }
             if (mTargetValue != mCurrentValue) {
                 postAnimationCallback();
@@ -201,14 +214,14 @@ class RampAnimator<T> {
          * If this is the first time the property is being set or if the rate is 0,
          * the value jumps directly to the target.
          *
-         * @param firstTarget The first target value.
-         * @param secondTarget The second target value.
+         * @param linearFirstTarget The first target value in linear space.
+         * @param linearSecondTarget The second target value in linear space.
          * @param rate The convergence rate in units per second, or 0 to set the value immediately.
          * @return True if either target differs from the previous target.
          */
-        public boolean animateTo(float firstTarget, float secondTarget, float rate) {
-            final boolean firstRetval = mFirst.animateTo(firstTarget, rate);
-            final boolean secondRetval = mSecond.animateTo(secondTarget, rate);
+        public boolean animateTo(float linearFirstTarget, float linearSecondTarget, float rate) {
+            final boolean firstRetval = mFirst.animateTo(linearFirstTarget, rate);
+            final boolean secondRetval = mSecond.animateTo(linearSecondTarget, rate);
             return firstRetval && secondRetval;
         }
 
diff --git a/services/core/xsd/display-device-config/display-device-config.xsd b/services/core/xsd/display-device-config/display-device-config.xsd
index 429edf175be4..a98483c6d03b 100644
--- a/services/core/xsd/display-device-config/display-device-config.xsd
+++ b/services/core/xsd/display-device-config/display-device-config.xsd
@@ -34,7 +34,8 @@
                     <xs:annotation name="nonnull"/>
                     <xs:annotation name="final"/>
                 </xs:element>
-                <xs:element type="highBrightnessMode" name="highBrightnessMode" minOccurs="0" maxOccurs="1"/>
+                <xs:element type="highBrightnessMode" name="highBrightnessMode" minOccurs="0"
+                            maxOccurs="1"/>
                 <xs:element type="displayQuirks" name="quirks" minOccurs="0" maxOccurs="1" />
                 <xs:element type="nonNegativeDecimal" name="screenBrightnessRampFastDecrease">
                     <xs:annotation name="final"/>
@@ -54,6 +55,19 @@
                 <xs:element type="sensorDetails" name="proxSensor">
                     <xs:annotation name="final"/>
                 </xs:element>
+
+                <!-- Set of thresholds that dictate the change needed for screen brightness
+                adaptations -->
+                <xs:element type="thresholds" name="displayBrightnessChangeThresholds">
+                    <xs:annotation name="nonnull"/>
+                    <xs:annotation name="final"/>
+                </xs:element>
+                <!-- Set of thresholds that dictate the change needed for ambient brightness
+                adaptations -->
+                <xs:element type="thresholds" name="ambientBrightnessChangeThresholds">
+                    <xs:annotation name="nonnull"/>
+                    <xs:annotation name="final"/>
+                </xs:element>
             </xs:sequence>
         </xs:complexType>
     </xs:element>
@@ -68,7 +82,8 @@
 
     <xs:complexType name="highBrightnessMode">
         <xs:all>
-            <xs:element name="transitionPoint" type="nonNegativeDecimal" minOccurs="1" maxOccurs="1">
+            <xs:element name="transitionPoint" type="nonNegativeDecimal" minOccurs="1"
+                        maxOccurs="1">
                 <xs:annotation name="nonnull"/>
                 <xs:annotation name="final"/>
             </xs:element>
@@ -97,7 +112,8 @@
 
     <xs:complexType name="hbmTiming">
         <xs:all>
-            <xs:element name="timeWindowSecs" type="xs:nonNegativeInteger" minOccurs="1" maxOccurs="1">
+            <xs:element name="timeWindowSecs" type="xs:nonNegativeInteger" minOccurs="1"
+                        maxOccurs="1">
                 <xs:annotation name="nonnull"/>
                 <xs:annotation name="final"/>
             </xs:element>
@@ -181,5 +197,31 @@
         </xs:sequence>
     </xs:complexType>
 
+    <!-- Thresholds for brightness changes. -->
+    <xs:complexType name="thresholds">
+        <xs:sequence>
+            <!-- Brightening thresholds. -->
+            <xs:element name="brighteningThresholds" type="brightnessThresholds" minOccurs="0"
+                        maxOccurs="1" >
+                <xs:annotation name="nonnull"/>
+                <xs:annotation name="final"/>
+            </xs:element>
+            <!-- Darkening thresholds. -->
+            <xs:element name="darkeningThresholds" type="brightnessThresholds" minOccurs="0"
+                        maxOccurs="1" >
+                <xs:annotation name="nonnull"/>
+                <xs:annotation name="final"/>
+            </xs:element>
+        </xs:sequence>
+    </xs:complexType>
+
+    <!-- Brightening and darkening minimum change thresholds. -->
+    <xs:complexType name="brightnessThresholds">
+        <!-- Minimum brightness change needed. -->
+        <xs:element name="minimum" type="nonNegativeDecimal" minOccurs="0" maxOccurs="1" >
+            <xs:annotation name="nonnull"/>
+            <xs:annotation name="final"/>
+        </xs:element>
+    </xs:complexType>
 
 </xs:schema>
diff --git a/services/core/xsd/display-device-config/schema/current.txt b/services/core/xsd/display-device-config/schema/current.txt
index ad186026d30c..df468d41fdef 100644
--- a/services/core/xsd/display-device-config/schema/current.txt
+++ b/services/core/xsd/display-device-config/schema/current.txt
@@ -1,8 +1,16 @@
 // Signature format: 2.0
 package com.android.server.display.config {
 
+  public class BrightnessThresholds {
+    ctor public BrightnessThresholds();
+    method @NonNull public final java.math.BigDecimal getMinimum();
+    method public final void setMinimum(@NonNull java.math.BigDecimal);
+  }
+
   public class DisplayConfiguration {
     ctor public DisplayConfiguration();
+    method @NonNull public final com.android.server.display.config.Thresholds getAmbientBrightnessChangeThresholds();
+    method @NonNull public final com.android.server.display.config.Thresholds getDisplayBrightnessChangeThresholds();
     method public com.android.server.display.config.HighBrightnessMode getHighBrightnessMode();
     method public final com.android.server.display.config.SensorDetails getLightSensor();
     method public final com.android.server.display.config.SensorDetails getProxSensor();
@@ -13,6 +21,8 @@ package com.android.server.display.config {
     method public final java.math.BigDecimal getScreenBrightnessRampFastIncrease();
     method public final java.math.BigDecimal getScreenBrightnessRampSlowDecrease();
     method public final java.math.BigDecimal getScreenBrightnessRampSlowIncrease();
+    method public final void setAmbientBrightnessChangeThresholds(@NonNull com.android.server.display.config.Thresholds);
+    method public final void setDisplayBrightnessChangeThresholds(@NonNull com.android.server.display.config.Thresholds);
     method public void setHighBrightnessMode(com.android.server.display.config.HighBrightnessMode);
     method public final void setLightSensor(com.android.server.display.config.SensorDetails);
     method public final void setProxSensor(com.android.server.display.config.SensorDetails);
@@ -100,6 +110,14 @@ package com.android.server.display.config {
     enum_constant public static final com.android.server.display.config.ThermalStatus shutdown;
   }
 
+  public class Thresholds {
+    ctor public Thresholds();
+    method @NonNull public final com.android.server.display.config.BrightnessThresholds getBrighteningThresholds();
+    method @NonNull public final com.android.server.display.config.BrightnessThresholds getDarkeningThresholds();
+    method public final void setBrighteningThresholds(@NonNull com.android.server.display.config.BrightnessThresholds);
+    method public final void setDarkeningThresholds(@NonNull com.android.server.display.config.BrightnessThresholds);
+  }
+
   public class XmlParser {
     ctor public XmlParser();
     method public static com.android.server.display.config.DisplayConfiguration read(java.io.InputStream) throws javax.xml.datatype.DatatypeConfigurationException, java.io.IOException, org.xmlpull.v1.XmlPullParserException;
diff --git a/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java b/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java
index bdf94f3a2882..356600d84099 100644
--- a/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/BrightnessTrackerTest.java
@@ -33,6 +33,7 @@ import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.ParceledListSlice;
 import android.database.ContentObserver;
+import android.hardware.Sensor;
 import android.hardware.SensorEvent;
 import android.hardware.SensorEventListener;
 import android.hardware.display.AmbientBrightnessDayStats;
@@ -42,6 +43,7 @@ import android.hardware.display.ColorDisplayManager;
 import android.hardware.display.DisplayManager;
 import android.hardware.display.DisplayedContentSample;
 import android.hardware.display.DisplayedContentSamplingAttributes;
+import android.hardware.input.InputSensorInfo;
 import android.os.BatteryManager;
 import android.os.Handler;
 import android.os.HandlerThread;
@@ -63,6 +65,8 @@ import com.android.internal.R;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
@@ -84,8 +88,11 @@ public class BrightnessTrackerTest {
     private static final String DEFAULT_DISPLAY_ID = "123";
     private static final float FLOAT_DELTA = 0.01f;
 
+    @Mock private InputSensorInfo mInputSensorInfoMock;
+
     private BrightnessTracker mTracker;
     private TestInjector mInjector;
+    private Sensor mLightSensorFake;
 
     private static Object sHandlerLock = new Object();
     private static Handler sHandler;
@@ -108,9 +115,12 @@ public class BrightnessTrackerTest {
 
     @Before
     public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
         mInjector = new TestInjector(ensureHandler());
+        mLightSensorFake = new Sensor(mInputSensorInfoMock);
 
         mTracker = new BrightnessTracker(InstrumentationRegistry.getContext(), mInjector);
+        mTracker.setLightSensor(mLightSensorFake);
         mDefaultNightModeColorTemperature =
                 InstrumentationRegistry.getContext().getResources().getInteger(
                 R.integer.config_nightDisplayColorTemperatureDefault);
@@ -834,6 +844,47 @@ public class BrightnessTrackerTest {
         mTracker.stop();
     }
 
+    @Test
+    public void testLightSensorChange() {
+        // verify the tracker started correctly and a listener registered
+        startTracker(mTracker);
+        assertNotNull(mInjector.mSensorListener);
+        assertEquals(mInjector.mLightSensor, mLightSensorFake);
+
+        // Setting the sensor to null should stop the registered listener.
+        mTracker.setLightSensor(null);
+        mInjector.waitForHandler();
+        assertNull(mInjector.mSensorListener);
+        assertNull(mInjector.mLightSensor);
+
+        // Resetting sensor should start listener again
+        mTracker.setLightSensor(mLightSensorFake);
+        mInjector.waitForHandler();
+        assertNotNull(mInjector.mSensorListener);
+        assertEquals(mInjector.mLightSensor, mLightSensorFake);
+
+        Sensor secondSensor = new Sensor(mInputSensorInfoMock);
+        // Setting a different listener should keep things working
+        mTracker.setLightSensor(secondSensor);
+        mInjector.waitForHandler();
+        assertNotNull(mInjector.mSensorListener);
+        assertEquals(mInjector.mLightSensor, secondSensor);
+    }
+
+    @Test
+    public void testSetLightSensorDoesntStartListener() {
+        mTracker.setLightSensor(mLightSensorFake);
+        assertNull(mInjector.mSensorListener);
+    }
+
+    @Test
+    public void testNullLightSensorWontRegister() {
+        mTracker.setLightSensor(null);
+        startTracker(mTracker);
+        assertNull(mInjector.mSensorListener);
+        assertNull(mInjector.mLightSensor);
+    }
+
     private InputStream getInputStream(String data) {
         return new ByteArrayInputStream(data.getBytes(StandardCharsets.UTF_8));
     }
@@ -924,6 +975,7 @@ public class BrightnessTrackerTest {
 
     private class TestInjector extends BrightnessTracker.Injector {
         SensorEventListener mSensorListener;
+        Sensor mLightSensor;
         BroadcastReceiver mBroadcastReceiver;
         DisplayManager.DisplayListener mDisplayListener;
         Map<String, Integer> mSecureIntSettings = new HashMap<>();
@@ -974,14 +1026,16 @@ public class BrightnessTrackerTest {
 
         @Override
         public void registerSensorListener(Context context,
-                SensorEventListener sensorListener, Handler handler) {
+                SensorEventListener sensorListener, Sensor lightSensor, Handler handler) {
             mSensorListener = sensorListener;
+            mLightSensor = lightSensor;
         }
 
         @Override
         public void unregisterSensorListener(Context context,
                 SensorEventListener sensorListener) {
             mSensorListener = null;
+            mLightSensor = null;
         }
 
         @Override