Merge "Add follower strategy"

27 files changed, 456 insertions, 17 deletions

diff --git a/services/core/java/com/android/server/display/AutomaticBrightnessController.java b/services/core/java/com/android/server/display/AutomaticBrightnessController.java
index 4f008357d151..10abfdd9f4ba 100644
--- a/services/core/java/com/android/server/display/AutomaticBrightnessController.java
+++ b/services/core/java/com/android/server/display/AutomaticBrightnessController.java
@@ -1127,6 +1127,14 @@ class AutomaticBrightnessController {
         }
     }
 
+    public float convertToFloatScale(float nits) {
+        if (mCurrentBrightnessMapper != null) {
+            return mCurrentBrightnessMapper.convertToFloatScale(nits);
+        } else {
+            return -1.0f;
+        }
+    }
+
     public void recalculateSplines(boolean applyAdjustment, float[] adjustment) {
         mCurrentBrightnessMapper.recalculateSplines(applyAdjustment, adjustment);
 
diff --git a/services/core/java/com/android/server/display/BrightnessMappingStrategy.java b/services/core/java/com/android/server/display/BrightnessMappingStrategy.java
index 3fc50c4edf6d..d7c1529aedc4 100644
--- a/services/core/java/com/android/server/display/BrightnessMappingStrategy.java
+++ b/services/core/java/com/android/server/display/BrightnessMappingStrategy.java
@@ -322,6 +322,13 @@ public abstract class BrightnessMappingStrategy {
     public abstract float convertToNits(float brightness);
 
     /**
+     * Converts the provided nits value to a float value if possible.
+     *
+     * Returns -1.0f if there's no available mapping for the nits to float.
+     */
+    public abstract float convertToFloatScale(float nits);
+
+    /**
      * Adds a user interaction data point to the brightness mapping.
      *
      * This data point <b>must</b> exist on the brightness curve as a result of this call. This is
@@ -671,6 +678,11 @@ public abstract class BrightnessMappingStrategy {
         }
 
         @Override
+        public float convertToFloatScale(float nits) {
+            return -1.0f;
+        }
+
+        @Override
         public void addUserDataPoint(float lux, float brightness) {
             float unadjustedBrightness = getUnadjustedBrightness(lux);
             if (mLoggingEnabled) {
@@ -913,6 +925,11 @@ public abstract class BrightnessMappingStrategy {
         }
 
         @Override
+        public float convertToFloatScale(float nits) {
+            return mNitsToBrightnessSpline.interpolate(nits);
+        }
+
+        @Override
         public void addUserDataPoint(float lux, float brightness) {
             float unadjustedBrightness = getUnadjustedBrightness(lux);
             if (mLoggingEnabled) {
diff --git a/services/core/java/com/android/server/display/DisplayManagerService.java b/services/core/java/com/android/server/display/DisplayManagerService.java
index 466070fe14b2..c1d8cf488c2c 100644
--- a/services/core/java/com/android/server/display/DisplayManagerService.java
+++ b/services/core/java/com/android/server/display/DisplayManagerService.java
@@ -1655,6 +1655,9 @@ public final class DisplayManagerService extends SystemService {
                 return;
             }
 
+            // TODO (b/265793751): Set this DPC as a follower of the default DPC if needed,
+            // clear this DPC's followers if it's not a lead display
+
             final String uniqueId = device.getUniqueId();
             HighBrightnessModeMetadata hbmMetadata = mHighBrightnessModeMetadataMap.get(uniqueId);
             dpc.onDisplayChanged(hbmMetadata);
diff --git a/services/core/java/com/android/server/display/DisplayPowerController.java b/services/core/java/com/android/server/display/DisplayPowerController.java
index 142ec68582f9..263c4d7ea683 100644
--- a/services/core/java/com/android/server/display/DisplayPowerController.java
+++ b/services/core/java/com/android/server/display/DisplayPowerController.java
@@ -54,6 +54,7 @@ import android.util.MathUtils;
 import android.util.MutableFloat;
 import android.util.MutableInt;
 import android.util.Slog;
+import android.util.SparseArray;
 import android.util.TimeUtils;
 import android.view.Display;
 
@@ -450,6 +451,10 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
     // PowerManager.BRIGHTNESS_INVALID_FLOAT when there's no temporary brightness set.
     private float mTemporaryScreenBrightness;
 
+    // This brightness value is set in concurrent displays mode. It is the brightness value
+    // of the lead display that this DPC should follow.
+    private float mBrightnessToFollow;
+
     // The last auto brightness adjustment that was set by the user and not temporary. Set to
     // Float.NaN when an auto-brightness adjustment hasn't been recorded yet.
     private float mAutoBrightnessAdjustment;
@@ -499,6 +504,12 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
     private boolean mIsEnabled;
     private boolean mIsInTransition;
 
+    // DPCs following the brightness of this DPC. This is used in concurrent displays mode - there
+    // is one lead display, the additional displays follow the brightness value of the lead display.
+    @GuardedBy("mLock")
+    private SparseArray<DisplayPowerControllerInterface> mDisplayBrightnessFollowers =
+            new SparseArray();
+
     /**
      * Creates the display power controller.
      */
@@ -635,6 +646,7 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
         loadProximitySensor();
 
         mCurrentScreenBrightnessSetting = getScreenBrightnessSetting();
+        mBrightnessToFollow = PowerManager.BRIGHTNESS_INVALID_FLOAT;
         mAutoBrightnessAdjustment = getAutoBrightnessAdjustmentSetting();
         mTemporaryScreenBrightness = PowerManager.BRIGHTNESS_INVALID_FLOAT;
         mPendingScreenBrightnessSetting = PowerManager.BRIGHTNESS_INVALID_FLOAT;
@@ -701,6 +713,48 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
         }
     }
 
+    @Override
+    public int getDisplayId() {
+        return mDisplayId;
+    }
+
+    @Override
+    public void setBrightnessToFollow(float leadDisplayBrightness, float nits) {
+        if (mAutomaticBrightnessController == null || nits < 0) {
+            mBrightnessToFollow = leadDisplayBrightness;
+        } else {
+            float brightness = mAutomaticBrightnessController.convertToFloatScale(nits);
+            if (isValidBrightnessValue(brightness)) {
+                mBrightnessToFollow = brightness;
+            } else {
+                // The device does not support nits
+                mBrightnessToFollow = leadDisplayBrightness;
+            }
+        }
+        sendUpdatePowerState();
+    }
+
+    @Override
+    public void addDisplayBrightnessFollower(DisplayPowerControllerInterface follower) {
+        synchronized (mLock) {
+            mDisplayBrightnessFollowers.append(follower.getDisplayId(), follower);
+        }
+        sendUpdatePowerState();
+    }
+
+    @Override
+    public void clearDisplayBrightnessFollowers() {
+        SparseArray<DisplayPowerControllerInterface> followers;
+        synchronized (mLock) {
+            followers = mDisplayBrightnessFollowers.clone();
+            mDisplayBrightnessFollowers.clear();
+        }
+        for (int i = 0; i < followers.size(); i++) {
+            DisplayPowerControllerInterface follower = followers.valueAt(i);
+            follower.setBrightnessToFollow(PowerManager.BRIGHTNESS_INVALID_FLOAT, /* nits= */ -1);
+        }
+    }
+
     @Nullable
     @Override
     public ParceledListSlice<AmbientBrightnessDayStats> getAmbientBrightnessStats(
@@ -1241,6 +1295,7 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
         int brightnessAdjustmentFlags = 0;
         mBrightnessReasonTemp.set(null);
         mTempBrightnessEvent.reset();
+        SparseArray<DisplayPowerControllerInterface> displayBrightnessFollowers;
         synchronized (mLock) {
             if (mStopped) {
                 return;
@@ -1269,6 +1324,8 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
             }
 
             mustNotify = !mDisplayReadyLocked;
+
+            displayBrightnessFollowers = mDisplayBrightnessFollowers.clone();
         }
 
         // Compute the basic display state using the policy.
@@ -1376,6 +1433,11 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
             mBrightnessReasonTemp.setReason(BrightnessReason.REASON_SCREEN_OFF);
         }
 
+        if (Float.isNaN(brightnessState) && isValidBrightnessValue(mBrightnessToFollow)) {
+            brightnessState = mBrightnessToFollow;
+            mBrightnessReasonTemp.setReason(BrightnessReason.REASON_FOLLOWER);
+        }
+
         if ((Float.isNaN(brightnessState))
                 && isValidBrightnessValue(mPowerRequest.screenBrightnessOverride)) {
             brightnessState = mPowerRequest.screenBrightnessOverride;
@@ -1557,6 +1619,11 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
             mAppliedThrottling = false;
         }
 
+        for (int i = 0; i < displayBrightnessFollowers.size(); i++) {
+            DisplayPowerControllerInterface follower = displayBrightnessFollowers.valueAt(i);
+            follower.setBrightnessToFollow(brightnessState, convertToNits(brightnessState));
+        }
+
         if (updateScreenBrightnessSetting) {
             // Tell the rest of the system about the new brightness in case we had to change it
             // for things like auto-brightness or high-brightness-mode. Note that we do this
@@ -2668,6 +2735,7 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
         pw.println("  mPendingScreenBrightnessSetting="
                 + mPendingScreenBrightnessSetting);
         pw.println("  mTemporaryScreenBrightness=" + mTemporaryScreenBrightness);
+        pw.println("  mBrightnessToFollow=" + mBrightnessToFollow);
         pw.println("  mAutoBrightnessAdjustment=" + mAutoBrightnessAdjustment);
         pw.println("  mBrightnessReason=" + mBrightnessReason);
         pw.println("  mTemporaryAutoBrightnessAdjustment=" + mTemporaryAutoBrightnessAdjustment);
diff --git a/services/core/java/com/android/server/display/DisplayPowerController2.java b/services/core/java/com/android/server/display/DisplayPowerController2.java
index ba9fe38c7cb4..0cc4e9386c92 100644
--- a/services/core/java/com/android/server/display/DisplayPowerController2.java
+++ b/services/core/java/com/android/server/display/DisplayPowerController2.java
@@ -52,6 +52,7 @@ import android.util.MathUtils;
 import android.util.MutableFloat;
 import android.util.MutableInt;
 import android.util.Slog;
+import android.util.SparseArray;
 import android.view.Display;
 
 import com.android.internal.R;
@@ -409,6 +410,13 @@ final class DisplayPowerController2 implements AutomaticBrightnessController.Cal
 
     private boolean mIsEnabled;
     private boolean mIsInTransition;
+
+    // DPCs following the brightness of this DPC. This is used in concurrent displays mode - there
+    // is one lead display, the additional displays follow the brightness value of the lead display.
+    @GuardedBy("mLock")
+    private SparseArray<DisplayPowerControllerInterface> mDisplayBrightnessFollowers =
+            new SparseArray();
+
     /**
      * Creates the display power controller.
      */
@@ -1110,6 +1118,7 @@ final class DisplayPowerController2 implements AutomaticBrightnessController.Cal
         boolean mustInitialize = false;
         int brightnessAdjustmentFlags = 0;
         mTempBrightnessEvent.reset();
+        SparseArray<DisplayPowerControllerInterface> displayBrightnessFollowers;
         synchronized (mLock) {
             if (mStopped) {
                 return;
@@ -1138,6 +1147,8 @@ final class DisplayPowerController2 implements AutomaticBrightnessController.Cal
             }
 
             mustNotify = !mDisplayReadyLocked;
+
+            displayBrightnessFollowers = mDisplayBrightnessFollowers.clone();
         }
 
         int state = mDisplayStateController
@@ -1321,6 +1332,11 @@ final class DisplayPowerController2 implements AutomaticBrightnessController.Cal
             mAppliedThrottling = false;
         }
 
+        for (int i = 0; i < displayBrightnessFollowers.size(); i++) {
+            DisplayPowerControllerInterface follower = displayBrightnessFollowers.valueAt(i);
+            follower.setBrightnessToFollow(brightnessState, convertToNits(brightnessState));
+        }
+
         if (updateScreenBrightnessSetting) {
             // Tell the rest of the system about the new brightness in case we had to change it
             // for things like auto-brightness or high-brightness-mode. Note that we do this
@@ -2097,6 +2113,27 @@ final class DisplayPowerController2 implements AutomaticBrightnessController.Cal
         mDisplayBrightnessController.setBrightness(brightnessValue);
     }
 
+    @Override
+    public int getDisplayId() {
+        return mDisplayId;
+    }
+
+    @Override
+    public void setBrightnessToFollow(float leadDisplayBrightness, float nits) {
+        if (mAutomaticBrightnessController == null || nits < 0) {
+            mDisplayBrightnessController.setBrightnessToFollow(leadDisplayBrightness);
+        } else {
+            float brightness = mAutomaticBrightnessController.convertToFloatScale(nits);
+            if (BrightnessUtils.isValidBrightnessValue(brightness)) {
+                mDisplayBrightnessController.setBrightnessToFollow(brightness);
+            } else {
+                // The device does not support nits
+                mDisplayBrightnessController.setBrightnessToFollow(leadDisplayBrightness);
+            }
+        }
+        sendUpdatePowerState();
+    }
+
     private void putAutoBrightnessAdjustmentSetting(float adjustment) {
         if (mDisplayId == Display.DEFAULT_DISPLAY) {
             mAutoBrightnessAdjustment = adjustment;
@@ -2147,6 +2184,27 @@ final class DisplayPowerController2 implements AutomaticBrightnessController.Cal
     }
 
     @Override
+    public void addDisplayBrightnessFollower(DisplayPowerControllerInterface follower) {
+        synchronized (mLock) {
+            mDisplayBrightnessFollowers.append(follower.getDisplayId(), follower);
+        }
+        sendUpdatePowerState();
+    }
+
+    @Override
+    public void clearDisplayBrightnessFollowers() {
+        SparseArray<DisplayPowerControllerInterface> followers;
+        synchronized (mLock) {
+            followers = mDisplayBrightnessFollowers.clone();
+            mDisplayBrightnessFollowers.clear();
+        }
+        for (int i = 0; i < followers.size(); i++) {
+            DisplayPowerControllerInterface follower = followers.valueAt(i);
+            follower.setBrightnessToFollow(PowerManager.BRIGHTNESS_INVALID_FLOAT, /* nits= */ -1);
+        }
+    }
+
+    @Override
     public void dump(final PrintWriter pw) {
         synchronized (mLock) {
             pw.println();
diff --git a/services/core/java/com/android/server/display/DisplayPowerControllerInterface.java b/services/core/java/com/android/server/display/DisplayPowerControllerInterface.java
index 7b0198465e68..a95ac74b27c8 100644
--- a/services/core/java/com/android/server/display/DisplayPowerControllerInterface.java
+++ b/services/core/java/com/android/server/display/DisplayPowerControllerInterface.java
@@ -161,4 +161,31 @@ public interface DisplayPowerControllerInterface {
      * @param newUserId The new userId
      */
     void onSwitchUser(int newUserId);
+
+    /**
+     * Get the ID of the display associated with this DPC.
+     * @return The display ID
+     */
+    int getDisplayId();
+
+    /**
+     * Set the brightness to follow if this is an additional display in a set of concurrent
+     * displays.
+     * @param leadDisplayBrightness The brightness of the lead display in the set of concurrent
+     *                              displays
+     * @param nits The brightness value in nits if the device supports nits
+     */
+    void setBrightnessToFollow(float leadDisplayBrightness, float nits);
+
+    /**
+     * Add an additional display that will copy the brightness value from this display. This is used
+     * when the device is in concurrent displays mode.
+     * @param follower The DPC that should copy the brightness value from this DPC
+     */
+    void addDisplayBrightnessFollower(DisplayPowerControllerInterface follower);
+
+    /**
+     * Clear all the additional displays following the brightness value of this display.
+     */
+    void clearDisplayBrightnessFollowers();
 }
diff --git a/services/core/java/com/android/server/display/brightness/BrightnessReason.java b/services/core/java/com/android/server/display/brightness/BrightnessReason.java
index a952004e7f9d..d7ae2699ee2d 100644
--- a/services/core/java/com/android/server/display/brightness/BrightnessReason.java
+++ b/services/core/java/com/android/server/display/brightness/BrightnessReason.java
@@ -38,7 +38,8 @@ public final class BrightnessReason {
     public static final int REASON_TEMPORARY = 7;
     public static final int REASON_BOOST = 8;
     public static final int REASON_SCREEN_OFF_BRIGHTNESS_SENSOR = 9;
-    public static final int REASON_MAX = REASON_SCREEN_OFF_BRIGHTNESS_SENSOR;
+    public static final int REASON_FOLLOWER = 10;
+    public static final int REASON_MAX = REASON_FOLLOWER;
 
     public static final int MODIFIER_DIMMED = 0x1;
     public static final int MODIFIER_LOW_POWER = 0x2;
@@ -193,6 +194,8 @@ public final class BrightnessReason {
                 return "boost";
             case REASON_SCREEN_OFF_BRIGHTNESS_SENSOR:
                 return "screen_off_brightness_sensor";
+            case REASON_FOLLOWER:
+                return "follower";
             default:
                 return Integer.toString(reason);
         }
diff --git a/services/core/java/com/android/server/display/brightness/DisplayBrightnessController.java b/services/core/java/com/android/server/display/brightness/DisplayBrightnessController.java
index e003ecb5cbad..13fcff3805d3 100644
--- a/services/core/java/com/android/server/display/brightness/DisplayBrightnessController.java
+++ b/services/core/java/com/android/server/display/brightness/DisplayBrightnessController.java
@@ -129,6 +129,16 @@ public final class DisplayBrightnessController {
     }
 
     /**
+     * Sets the brightness to follow
+     */
+    public void setBrightnessToFollow(Float brightnessToFollow) {
+        synchronized (mLock) {
+            mDisplayBrightnessStrategySelector.getFollowerDisplayBrightnessStrategy()
+                    .setBrightnessToFollow(brightnessToFollow);
+        }
+    }
+
+    /**
      * Returns a boolean flag indicating if the light sensor is to be used to decide the screen
      * brightness when dozing
      */
diff --git a/services/core/java/com/android/server/display/brightness/DisplayBrightnessStrategySelector.java b/services/core/java/com/android/server/display/brightness/DisplayBrightnessStrategySelector.java
index 7d05f139c69d..02ca2d33fc99 100644
--- a/services/core/java/com/android/server/display/brightness/DisplayBrightnessStrategySelector.java
+++ b/services/core/java/com/android/server/display/brightness/DisplayBrightnessStrategySelector.java
@@ -28,6 +28,7 @@ import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.display.brightness.strategy.BoostBrightnessStrategy;
 import com.android.server.display.brightness.strategy.DisplayBrightnessStrategy;
 import com.android.server.display.brightness.strategy.DozeBrightnessStrategy;
+import com.android.server.display.brightness.strategy.FollowerBrightnessStrategy;
 import com.android.server.display.brightness.strategy.InvalidBrightnessStrategy;
 import com.android.server.display.brightness.strategy.OverrideBrightnessStrategy;
 import com.android.server.display.brightness.strategy.ScreenOffBrightnessStrategy;
@@ -55,6 +56,8 @@ public class DisplayBrightnessStrategySelector {
     private final TemporaryBrightnessStrategy mTemporaryBrightnessStrategy;
     // The brightness strategy used to manage the brightness state when boost is requested
     private final BoostBrightnessStrategy mBoostBrightnessStrategy;
+    // The brightness strategy used for additional displays
+    private final FollowerBrightnessStrategy mFollowerBrightnessStrategy;
     // The brightness strategy used to manage the brightness state when the request is invalid.
     private final InvalidBrightnessStrategy mInvalidBrightnessStrategy;
 
@@ -76,6 +79,7 @@ public class DisplayBrightnessStrategySelector {
         mOverrideBrightnessStrategy = injector.getOverrideBrightnessStrategy();
         mTemporaryBrightnessStrategy = injector.getTemporaryBrightnessStrategy();
         mBoostBrightnessStrategy = injector.getBoostBrightnessStrategy();
+        mFollowerBrightnessStrategy = injector.getFollowerBrightnessStrategy(displayId);
         mInvalidBrightnessStrategy = injector.getInvalidBrightnessStrategy();
         mAllowAutoBrightnessWhileDozingConfig = context.getResources().getBoolean(
                 R.bool.config_allowAutoBrightnessWhileDozing);
@@ -93,10 +97,13 @@ public class DisplayBrightnessStrategySelector {
         DisplayBrightnessStrategy displayBrightnessStrategy = mInvalidBrightnessStrategy;
         if (targetDisplayState == Display.STATE_OFF) {
             displayBrightnessStrategy = mScreenOffBrightnessStrategy;
-        } else if (displayPowerRequest.boostScreenBrightness) {
-            displayBrightnessStrategy = mBoostBrightnessStrategy;
         } else if (shouldUseDozeBrightnessStrategy(displayPowerRequest)) {
             displayBrightnessStrategy = mDozeBrightnessStrategy;
+        } else if (BrightnessUtils.isValidBrightnessValue(
+                mFollowerBrightnessStrategy.getBrightnessToFollow())) {
+            displayBrightnessStrategy = mFollowerBrightnessStrategy;
+        } else if (displayPowerRequest.boostScreenBrightness) {
+            displayBrightnessStrategy = mBoostBrightnessStrategy;
         } else if (BrightnessUtils
                 .isValidBrightnessValue(displayPowerRequest.screenBrightnessOverride)) {
             displayBrightnessStrategy = mOverrideBrightnessStrategy;
@@ -119,6 +126,10 @@ public class DisplayBrightnessStrategySelector {
         return mTemporaryBrightnessStrategy;
     }
 
+    public FollowerBrightnessStrategy getFollowerDisplayBrightnessStrategy() {
+        return mFollowerBrightnessStrategy;
+    }
+
     /**
      * Returns a boolean flag indicating if the light sensor is to be used to decide the screen
      * brightness when dozing
@@ -180,6 +191,10 @@ public class DisplayBrightnessStrategySelector {
             return new BoostBrightnessStrategy();
         }
 
+        FollowerBrightnessStrategy getFollowerBrightnessStrategy(int displayId) {
+            return new FollowerBrightnessStrategy(displayId);
+        }
+
         InvalidBrightnessStrategy getInvalidBrightnessStrategy() {
             return new InvalidBrightnessStrategy();
         }
diff --git a/services/core/java/com/android/server/display/brightness/strategy/BoostBrightnessStrategy.java b/services/core/java/com/android/server/display/brightness/strategy/BoostBrightnessStrategy.java
index 475ef5012751..0cf234b09830 100644
--- a/services/core/java/com/android/server/display/brightness/strategy/BoostBrightnessStrategy.java
+++ b/services/core/java/com/android/server/display/brightness/strategy/BoostBrightnessStrategy.java
@@ -35,7 +35,8 @@ public class BoostBrightnessStrategy implements DisplayBrightnessStrategy {
     @Override
     public DisplayBrightnessState updateBrightness(
             DisplayManagerInternal.DisplayPowerRequest displayPowerRequest) {
-        // Todo(brup): Introduce a validator class and add validations before setting the brightness
+        // Todo(b/241308599): Introduce a validator class and add validations before setting
+        // the brightness
         DisplayBrightnessState displayBrightnessState =
                 BrightnessUtils.constructDisplayBrightnessState(BrightnessReason.REASON_BOOST,
                         PowerManager.BRIGHTNESS_MAX,
diff --git a/services/core/java/com/android/server/display/brightness/strategy/DozeBrightnessStrategy.java b/services/core/java/com/android/server/display/brightness/strategy/DozeBrightnessStrategy.java
index 0bc900b664b1..98075f91c28b 100644
--- a/services/core/java/com/android/server/display/brightness/strategy/DozeBrightnessStrategy.java
+++ b/services/core/java/com/android/server/display/brightness/strategy/DozeBrightnessStrategy.java
@@ -30,7 +30,8 @@ public class DozeBrightnessStrategy implements DisplayBrightnessStrategy {
     @Override
     public DisplayBrightnessState updateBrightness(
             DisplayManagerInternal.DisplayPowerRequest displayPowerRequest) {
-        // Todo(brup): Introduce a validator class and add validations before setting the brightness
+        // Todo(b/241308599): Introduce a validator class and add validations before setting
+        // the brightness
         return BrightnessUtils.constructDisplayBrightnessState(BrightnessReason.REASON_DOZE,
                 displayPowerRequest.dozeScreenBrightness, displayPowerRequest.dozeScreenBrightness);
     }
diff --git a/services/core/java/com/android/server/display/brightness/strategy/FollowerBrightnessStrategy.java b/services/core/java/com/android/server/display/brightness/strategy/FollowerBrightnessStrategy.java
new file mode 100644
index 000000000000..fe684a4a0c56
--- /dev/null
+++ b/services/core/java/com/android/server/display/brightness/strategy/FollowerBrightnessStrategy.java
@@ -0,0 +1,75 @@
+/*
+ * 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.brightness.strategy;
+
+import android.hardware.display.DisplayManagerInternal;
+import android.os.PowerManager;
+
+import com.android.server.display.DisplayBrightnessState;
+import com.android.server.display.brightness.BrightnessReason;
+import com.android.server.display.brightness.BrightnessUtils;
+
+import java.io.PrintWriter;
+
+/**
+ * Manages the brightness of an additional display that copies the brightness value from the lead
+ * display when the device is using concurrent displays.
+ */
+public class FollowerBrightnessStrategy implements DisplayBrightnessStrategy {
+
+    // The ID of the LogicalDisplay using this strategy.
+    private final int mDisplayId;
+
+    // Set to PowerManager.BRIGHTNESS_INVALID_FLOAT when there's no brightness to follow set.
+    private float mBrightnessToFollow;
+
+    public FollowerBrightnessStrategy(int displayId) {
+        mDisplayId = displayId;
+        mBrightnessToFollow = PowerManager.BRIGHTNESS_INVALID_FLOAT;
+    }
+
+    @Override
+    public DisplayBrightnessState updateBrightness(
+            DisplayManagerInternal.DisplayPowerRequest displayPowerRequest) {
+        // Todo(b/241308599): Introduce a validator class and add validations before setting
+        // the brightness
+        return BrightnessUtils.constructDisplayBrightnessState(BrightnessReason.REASON_FOLLOWER,
+                mBrightnessToFollow, mBrightnessToFollow);
+    }
+
+    @Override
+    public String getName() {
+        return "FollowerBrightnessStrategy";
+    }
+
+    public float getBrightnessToFollow() {
+        return mBrightnessToFollow;
+    }
+
+    public void setBrightnessToFollow(float brightnessToFollow) {
+        mBrightnessToFollow = brightnessToFollow;
+    }
+
+    /**
+     * Dumps the state of this class.
+     */
+    public void dump(PrintWriter writer) {
+        writer.println("FollowerBrightnessStrategy:");
+        writer.println("  mDisplayId=" + mDisplayId);
+        writer.println("  mBrightnessToFollow:" + mBrightnessToFollow);
+    }
+}
diff --git a/services/core/java/com/android/server/display/brightness/strategy/OverrideBrightnessStrategy.java b/services/core/java/com/android/server/display/brightness/strategy/OverrideBrightnessStrategy.java
index f03f03602a51..6d3830abd561 100644
--- a/services/core/java/com/android/server/display/brightness/strategy/OverrideBrightnessStrategy.java
+++ b/services/core/java/com/android/server/display/brightness/strategy/OverrideBrightnessStrategy.java
@@ -29,7 +29,8 @@ public class OverrideBrightnessStrategy implements DisplayBrightnessStrategy {
     @Override
     public DisplayBrightnessState updateBrightness(
             DisplayManagerInternal.DisplayPowerRequest displayPowerRequest) {
-        // Todo(brup): Introduce a validator class and add validations before setting the brightness
+        // Todo(b/241308599): Introduce a validator class and add validations before setting
+        // the brightness
         return BrightnessUtils.constructDisplayBrightnessState(BrightnessReason.REASON_OVERRIDE,
                 displayPowerRequest.screenBrightnessOverride,
                 displayPowerRequest.screenBrightnessOverride);
diff --git a/services/core/java/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategy.java b/services/core/java/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategy.java
index 396fa06ffe18..ee5e0664748d 100644
--- a/services/core/java/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategy.java
+++ b/services/core/java/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategy.java
@@ -30,7 +30,8 @@ public class ScreenOffBrightnessStrategy implements DisplayBrightnessStrategy {
     @Override
     public DisplayBrightnessState updateBrightness(
             DisplayManagerInternal.DisplayPowerRequest displayPowerRequest) {
-        // Todo(brup): Introduce a validator class and add validations before setting the brightness
+        // Todo(b/241308599): Introduce a validator class and add validations before setting
+        // the brightness
         return BrightnessUtils.constructDisplayBrightnessState(BrightnessReason.REASON_SCREEN_OFF,
                 PowerManager.BRIGHTNESS_OFF_FLOAT,
                 PowerManager.BRIGHTNESS_OFF_FLOAT);
diff --git a/services/core/java/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategy.java b/services/core/java/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategy.java
index 7d759ca84f67..d97415d67616 100644
--- a/services/core/java/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategy.java
+++ b/services/core/java/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategy.java
@@ -43,7 +43,8 @@ public class TemporaryBrightnessStrategy implements DisplayBrightnessStrategy {
     @Override
     public DisplayBrightnessState updateBrightness(
             DisplayManagerInternal.DisplayPowerRequest displayPowerRequest) {
-        // Todo(brup): Introduce a validator class and add validations before setting the brightness
+        // Todo(b/241308599): Introduce a validator class and add validations before setting
+        // the brightness
         DisplayBrightnessState displayBrightnessState =
                 BrightnessUtils.constructDisplayBrightnessState(BrightnessReason.REASON_TEMPORARY,
                         mTemporaryScreenBrightness,
diff --git a/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerController2Test.java b/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerController2Test.java
index 2a790a1c8e57..3d36c1c16338 100644
--- a/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerController2Test.java
+++ b/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerController2Test.java
@@ -18,6 +18,8 @@ package com.android.server.display;
 
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.verify;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.ArgumentMatchers.isA;
@@ -253,4 +255,35 @@ public final class DisplayPowerController2Test {
                 });
         when(mDisplayDeviceConfigMock.getNits()).thenReturn(new float[]{2, 500});
     }
+
+    @Test
+    public void testDisplayBrightnessFollowers() {
+        setUpDisplay(DISPLAY_ID, UNIQUE_DISPLAY_ID);
+
+        DisplayPowerController2 defaultDpc = new DisplayPowerController2(
+                mContextSpy, mInjector, mDisplayPowerCallbacksMock, mHandler,
+                mSensorManagerMock, mDisplayBlankerMock, mLogicalDisplayMock,
+                mBrightnessTrackerMock, mBrightnessSettingMock, () -> {
+        }, mHighBrightnessModeMetadataMock);
+        DisplayPowerController2 followerDpc = new DisplayPowerController2(
+                mContextSpy, mInjector, mDisplayPowerCallbacksMock, mHandler,
+                mSensorManagerMock, mDisplayBlankerMock, mLogicalDisplayMock,
+                mBrightnessTrackerMock, mBrightnessSettingMock, () -> {
+        }, mHighBrightnessModeMetadataMock);
+
+        defaultDpc.addDisplayBrightnessFollower(followerDpc);
+
+        defaultDpc.setBrightness(0.3f);
+        assertEquals(defaultDpc.getBrightnessInfo().brightness,
+                followerDpc.getBrightnessInfo().brightness, 0);
+
+        defaultDpc.setBrightness(0.6f);
+        assertEquals(defaultDpc.getBrightnessInfo().brightness,
+                followerDpc.getBrightnessInfo().brightness, 0);
+
+        float brightness = 0.1f;
+        defaultDpc.clearDisplayBrightnessFollowers();
+        defaultDpc.setBrightness(brightness);
+        assertNotEquals(brightness, followerDpc.getBrightnessInfo().brightness, 0);
+    }
 }
diff --git a/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerControllerTest.java b/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerControllerTest.java
index d99ed7877ca8..b6388ccbc653 100644
--- a/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerControllerTest.java
+++ b/services/tests/mockingservicestests/src/com/android/server/display/DisplayPowerControllerTest.java
@@ -19,6 +19,8 @@ package com.android.server.display;
 import static com.android.dx.mockito.inline.extended.ExtendedMockito.verify;
 
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.ArgumentMatchers.isA;
@@ -235,4 +237,35 @@ public final class DisplayPowerControllerTest {
                 });
         when(mDisplayDeviceConfigMock.getNits()).thenReturn(new float[]{2, 500});
     }
+
+    @Test
+    public void testDisplayBrightnessFollowers() {
+        setUpDisplay(DISPLAY_ID, UNIQUE_DISPLAY_ID);
+
+        DisplayPowerController defaultDpc = new DisplayPowerController(
+                mContextSpy, mInjector, mDisplayPowerCallbacksMock, mHandler,
+                mSensorManagerMock, mDisplayBlankerMock, mLogicalDisplayMock,
+                mBrightnessTrackerMock, mBrightnessSettingMock, () -> {
+        }, mHighBrightnessModeMetadataMock);
+        DisplayPowerController followerDpc = new DisplayPowerController(
+                mContextSpy, mInjector, mDisplayPowerCallbacksMock, mHandler,
+                mSensorManagerMock, mDisplayBlankerMock, mLogicalDisplayMock,
+                mBrightnessTrackerMock, mBrightnessSettingMock, () -> {
+        }, mHighBrightnessModeMetadataMock);
+
+        defaultDpc.addDisplayBrightnessFollower(followerDpc);
+
+        defaultDpc.setBrightness(0.3f);
+        assertEquals(defaultDpc.getBrightnessInfo().brightness,
+                followerDpc.getBrightnessInfo().brightness, 0);
+
+        defaultDpc.setBrightness(0.6f);
+        assertEquals(defaultDpc.getBrightnessInfo().brightness,
+                followerDpc.getBrightnessInfo().brightness, 0);
+
+        float brightness = 0.1f;
+        defaultDpc.clearDisplayBrightnessFollowers();
+        defaultDpc.setBrightness(brightness);
+        assertNotEquals(brightness, followerDpc.getBrightnessInfo().brightness, 0);
+    }
 }
diff --git a/services/tests/servicestests/src/com/android/server/display/DisplayDeviceConfigTest.java b/services/tests/servicestests/src/com/android/server/display/DisplayDeviceConfigTest.java
index 82b89bbb0464..91fd76ec4b70 100644
--- a/services/tests/servicestests/src/com/android/server/display/DisplayDeviceConfigTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/DisplayDeviceConfigTest.java
@@ -164,7 +164,7 @@ public final class DisplayDeviceConfigTest {
         assertArrayEquals(new int[]{-1, 10, 20, 30, 40},
                 mDisplayDeviceConfig.getScreenOffBrightnessSensorValueToLux());
 
-        // Todo(brup): Add asserts for BrightnessThrottlingData, DensityMapping,
+        // Todo: Add asserts for BrightnessThrottlingData, DensityMapping,
         // HighBrightnessModeData AmbientLightSensor, RefreshRateLimitations and ProximitySensor.
     }
 
@@ -236,7 +236,7 @@ public final class DisplayDeviceConfigTest {
         assertArrayEquals(mDisplayDeviceConfig.getHighAmbientBrightnessThresholds(),
                 HIGH_AMBIENT_THRESHOLD_OF_PEAK_REFRESH_RATE);
 
-        // Todo(brup): Add asserts for BrightnessThrottlingData, DensityMapping,
+        // Todo: Add asserts for BrightnessThrottlingData, DensityMapping,
         // HighBrightnessModeData AmbientLightSensor, RefreshRateLimitations and ProximitySensor.
     }
 
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/BrightnessReasonTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/BrightnessReasonTest.java
index 57aa61a0ebd2..e58b3e891b70 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/BrightnessReasonTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/BrightnessReasonTest.java
@@ -65,7 +65,7 @@ public final class BrightnessReasonTest {
 
     @Test
     public void setReasonDoesntSetIfModifierIsBeyondExtremes() {
-        int extremeReason = 10;
+        int extremeReason = BrightnessReason.REASON_MAX + 1;
         mBrightnessReason.setReason(extremeReason);
         assertEquals(mBrightnessReason.getReason(), BrightnessReason.REASON_DOZE);
 
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessControllerTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessControllerTest.java
index c24d83f0f878..d4ab794f55dc 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessControllerTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessControllerTest.java
@@ -75,7 +75,7 @@ public final class DisplayBrightnessControllerTest {
     }
 
     @Test
-    public void updateBrightness() {
+    public void testUpdateBrightness() {
         DisplayPowerRequest displayPowerRequest = mock(DisplayPowerRequest.class);
         DisplayBrightnessStrategy displayBrightnessStrategy = mock(DisplayBrightnessStrategy.class);
         int targetDisplayState = Display.STATE_DOZE;
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessStrategySelectorTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessStrategySelectorTest.java
index dcf217c35c18..a9e616d766c6 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessStrategySelectorTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/DisplayBrightnessStrategySelectorTest.java
@@ -31,6 +31,7 @@ import androidx.test.runner.AndroidJUnit4;
 import com.android.internal.R;
 import com.android.server.display.brightness.strategy.BoostBrightnessStrategy;
 import com.android.server.display.brightness.strategy.DozeBrightnessStrategy;
+import com.android.server.display.brightness.strategy.FollowerBrightnessStrategy;
 import com.android.server.display.brightness.strategy.InvalidBrightnessStrategy;
 import com.android.server.display.brightness.strategy.OverrideBrightnessStrategy;
 import com.android.server.display.brightness.strategy.ScreenOffBrightnessStrategy;
@@ -61,6 +62,8 @@ public final class DisplayBrightnessStrategySelectorTest {
     @Mock
     private InvalidBrightnessStrategy mInvalidBrightnessStrategy;
     @Mock
+    private FollowerBrightnessStrategy mFollowerBrightnessStrategy;
+    @Mock
     private Context mContext;
     @Mock
     private Resources mResources;
@@ -100,6 +103,11 @@ public final class DisplayBrightnessStrategySelectorTest {
                     }
 
                     @Override
+                    FollowerBrightnessStrategy getFollowerBrightnessStrategy(int displayId) {
+                        return mFollowerBrightnessStrategy;
+                    }
+
+                    @Override
                     InvalidBrightnessStrategy getInvalidBrightnessStrategy() {
                         return mInvalidBrightnessStrategy;
                     }
@@ -133,6 +141,7 @@ public final class DisplayBrightnessStrategySelectorTest {
         DisplayManagerInternal.DisplayPowerRequest displayPowerRequest = mock(
                 DisplayManagerInternal.DisplayPowerRequest.class);
         displayPowerRequest.screenBrightnessOverride = 0.4f;
+        when(mFollowerBrightnessStrategy.getBrightnessToFollow()).thenReturn(Float.NaN);
         assertEquals(mDisplayBrightnessStrategySelector.selectStrategy(displayPowerRequest,
                 Display.STATE_ON), mOverrideBrightnessStrategy);
     }
@@ -142,6 +151,7 @@ public final class DisplayBrightnessStrategySelectorTest {
         DisplayManagerInternal.DisplayPowerRequest displayPowerRequest = mock(
                 DisplayManagerInternal.DisplayPowerRequest.class);
         displayPowerRequest.screenBrightnessOverride = Float.NaN;
+        when(mFollowerBrightnessStrategy.getBrightnessToFollow()).thenReturn(Float.NaN);
         when(mTemporaryBrightnessStrategy.getTemporaryScreenBrightness()).thenReturn(0.3f);
         assertEquals(mDisplayBrightnessStrategySelector.selectStrategy(displayPowerRequest,
                 Display.STATE_ON), mTemporaryBrightnessStrategy);
@@ -152,6 +162,7 @@ public final class DisplayBrightnessStrategySelectorTest {
         DisplayManagerInternal.DisplayPowerRequest displayPowerRequest = mock(
                 DisplayManagerInternal.DisplayPowerRequest.class);
         displayPowerRequest.boostScreenBrightness = true;
+        when(mFollowerBrightnessStrategy.getBrightnessToFollow()).thenReturn(Float.NaN);
         displayPowerRequest.screenBrightnessOverride = Float.NaN;
         when(mTemporaryBrightnessStrategy.getTemporaryScreenBrightness()).thenReturn(Float.NaN);
         assertEquals(mDisplayBrightnessStrategySelector.selectStrategy(displayPowerRequest,
@@ -163,8 +174,18 @@ public final class DisplayBrightnessStrategySelectorTest {
         DisplayManagerInternal.DisplayPowerRequest displayPowerRequest = mock(
                 DisplayManagerInternal.DisplayPowerRequest.class);
         displayPowerRequest.screenBrightnessOverride = Float.NaN;
+        when(mFollowerBrightnessStrategy.getBrightnessToFollow()).thenReturn(Float.NaN);
         when(mTemporaryBrightnessStrategy.getTemporaryScreenBrightness()).thenReturn(Float.NaN);
         assertEquals(mDisplayBrightnessStrategySelector.selectStrategy(displayPowerRequest,
                 Display.STATE_ON), mInvalidBrightnessStrategy);
     }
+
+    @Test
+    public void selectStrategySelectsFollowerStrategyWhenValid() {
+        DisplayManagerInternal.DisplayPowerRequest displayPowerRequest = mock(
+                DisplayManagerInternal.DisplayPowerRequest.class);
+        when(mFollowerBrightnessStrategy.getBrightnessToFollow()).thenReturn(0.3f);
+        assertEquals(mDisplayBrightnessStrategySelector.selectStrategy(displayPowerRequest,
+                Display.STATE_ON), mFollowerBrightnessStrategy);
+    }
 }
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/BoostBrightnessStrategyTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/BoostBrightnessStrategyTest.java
index 431a239ab4fd..c1de8943b73a 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/BoostBrightnessStrategyTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/BoostBrightnessStrategyTest.java
@@ -44,7 +44,7 @@ public class BoostBrightnessStrategyTest {
     }
 
     @Test
-    public void updateBrightnessWorksAsExpectedWhenBoostBrightnessIsRequested() {
+    public void testUpdateBrightnessWhenBoostBrightnessIsRequested() {
         DisplayManagerInternal.DisplayPowerRequest
                 displayPowerRequest = new DisplayManagerInternal.DisplayPowerRequest();
         displayPowerRequest.boostScreenBrightness = true;
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/DozeBrightnessStrategyTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/DozeBrightnessStrategyTest.java
index 29652ff0396b..76fa17287726 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/DozeBrightnessStrategyTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/DozeBrightnessStrategyTest.java
@@ -41,7 +41,7 @@ public class DozeBrightnessStrategyTest {
     }
 
     @Test
-    public void updateBrightnessWorksAsExpectedWhenScreenDozeStateIsRequested() {
+    public void testUpdateBrightnessWhenScreenDozeStateIsRequested() {
         DisplayPowerRequest displayPowerRequest = new DisplayPowerRequest();
         float dozeScreenBrightness = 0.2f;
         displayPowerRequest.dozeScreenBrightness = dozeScreenBrightness;
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/FollowerBrightnessStrategyTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/FollowerBrightnessStrategyTest.java
new file mode 100644
index 000000000000..f20404e25afc
--- /dev/null
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/FollowerBrightnessStrategyTest.java
@@ -0,0 +1,63 @@
+/*
+ * 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.brightness.strategy;
+
+import static org.junit.Assert.assertEquals;
+
+import android.hardware.display.DisplayManagerInternal;
+import android.view.Display;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import com.android.server.display.DisplayBrightnessState;
+import com.android.server.display.brightness.BrightnessReason;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class FollowerBrightnessStrategyTest {
+    private FollowerBrightnessStrategy mFollowerBrightnessStrategy;
+
+    @Before
+    public void before() {
+        mFollowerBrightnessStrategy = new FollowerBrightnessStrategy(Display.DEFAULT_DISPLAY);
+    }
+
+    @Test
+    public void testUpdateBrightness() {
+        DisplayManagerInternal.DisplayPowerRequest
+                displayPowerRequest = new DisplayManagerInternal.DisplayPowerRequest();
+        float brightnessToFollow = 0.2f;
+        mFollowerBrightnessStrategy.setBrightnessToFollow(brightnessToFollow);
+        BrightnessReason brightnessReason = new BrightnessReason();
+        brightnessReason.setReason(BrightnessReason.REASON_FOLLOWER);
+        DisplayBrightnessState expectedDisplayBrightnessState =
+                new DisplayBrightnessState.Builder()
+                        .setBrightness(brightnessToFollow)
+                        .setBrightnessReason(brightnessReason)
+                        .setSdrBrightness(brightnessToFollow)
+                        .build();
+        DisplayBrightnessState updatedDisplayBrightnessState =
+                mFollowerBrightnessStrategy.updateBrightness(displayPowerRequest);
+        assertEquals(expectedDisplayBrightnessState, updatedDisplayBrightnessState);
+    }
+
+}
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/OverrideBrightnessStrategyTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/OverrideBrightnessStrategyTest.java
index 4d89c28e3cf1..2487b32bbd9d 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/OverrideBrightnessStrategyTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/OverrideBrightnessStrategyTest.java
@@ -43,7 +43,7 @@ public class OverrideBrightnessStrategyTest {
     }
 
     @Test
-    public void updateBrightnessWorksAsExpectedWhenScreenDozeStateIsRequested() {
+    public void testUpdateBrightnessWhenScreenDozeStateIsRequested() {
         DisplayManagerInternal.DisplayPowerRequest
                 displayPowerRequest = new DisplayManagerInternal.DisplayPowerRequest();
         float overrideBrightness = 0.2f;
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategyTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategyTest.java
index 050547550c95..353e92e234e4 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategyTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/ScreenOffBrightnessStrategyTest.java
@@ -43,7 +43,7 @@ public final class ScreenOffBrightnessStrategyTest {
     }
 
     @Test
-    public void updateBrightnessWorksAsExpectedWhenScreenOffDisplayState() {
+    public void testUpdateBrightnessWhenScreenOffDisplayState() {
         DisplayPowerRequest displayPowerRequest = new DisplayPowerRequest();
         BrightnessReason brightnessReason = new BrightnessReason();
         brightnessReason.setReason(BrightnessReason.REASON_SCREEN_OFF);
diff --git a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategyTest.java b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategyTest.java
index b92aa9ce139c..99679a3ce5df 100644
--- a/services/tests/servicestests/src/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategyTest.java
+++ b/services/tests/servicestests/src/com/android/server/display/brightness/strategy/TemporaryBrightnessStrategyTest.java
@@ -43,7 +43,7 @@ public class TemporaryBrightnessStrategyTest {
     }
 
     @Test
-    public void updateBrightnessWorksAsExpectedWhenTemporaryBrightnessIsSet() {
+    public void testUpdateBrightnessWhenTemporaryBrightnessIsSet() {
         DisplayManagerInternal.DisplayPowerRequest
                 displayPowerRequest = new DisplayManagerInternal.DisplayPowerRequest();
         float temporaryBrightness = 0.2f;