diff --git a/services/core/java/com/android/server/display/DisplayModeDirector.java b/services/core/java/com/android/server/display/DisplayModeDirector.java
index 186986e17c142..0d1b3d6f0ffd4 100644
--- a/services/core/java/com/android/server/display/DisplayModeDirector.java
+++ b/services/core/java/com/android/server/display/DisplayModeDirector.java
@@ -52,6 +52,7 @@ import android.view.Display;
 import android.view.DisplayInfo;
 
 import com.android.internal.R;
+import com.android.internal.annotations.GuardedBy;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.internal.os.BackgroundThread;
 import com.android.server.LocalServices;
@@ -2127,7 +2128,7 @@ public class DisplayModeDirector {
         }
     }
 
-    private final class SensorObserver implements ProximityActiveListener,
+    private static final class SensorObserver implements ProximityActiveListener,
             DisplayManager.DisplayListener {
         private final String mProximitySensorName = null;
         private final String mProximitySensorType = Sensor.STRING_TYPE_PROXIMITY;
@@ -2135,22 +2136,24 @@ public class DisplayModeDirector {
         private final BallotBox mBallotBox;
         private final Context mContext;
         private final Injector mInjector;
+        @GuardedBy("mSensorObserverLock")
+        private final SparseBooleanArray mDozeStateByDisplay = new SparseBooleanArray();
+        private final Object mSensorObserverLock = new Object();
 
         private DisplayManager mDisplayManager;
         private DisplayManagerInternal mDisplayManagerInternal;
+        @GuardedBy("mSensorObserverLock")
         private boolean mIsProxActive = false;
-        private final SparseBooleanArray mDozeStateByDisplay;
 
         SensorObserver(Context context, BallotBox ballotBox, Injector injector) {
             mContext = context;
             mBallotBox = ballotBox;
             mInjector = injector;
-            mDozeStateByDisplay = new SparseBooleanArray();
         }
 
         @Override
         public void onProximityActive(boolean isActive) {
-            synchronized (mLock) {
+            synchronized (mSensorObserverLock) {
                 if (mIsProxActive != isActive) {
                     mIsProxActive = isActive;
                     recalculateVotesLocked();
@@ -2166,7 +2169,7 @@ public class DisplayModeDirector {
                     LocalServices.getService(SensorManagerInternal.class);
             sensorManager.addProximityActiveListener(BackgroundThread.getExecutor(), this);
 
-            synchronized (mLock) {
+            synchronized (mSensorObserverLock) {
                 for (Display d : mDisplayManager.getDisplays()) {
                     mDozeStateByDisplay.put(d.getDisplayId(), mInjector.isDozeState(d));
                 }
@@ -2196,19 +2199,21 @@ public class DisplayModeDirector {
 
         void dumpLocked(PrintWriter pw) {
             pw.println("  SensorObserver");
-            pw.println("    mIsProxActive=" + mIsProxActive);
-            pw.println("    mDozeStateByDisplay:");
-            for (int i = 0; i < mDozeStateByDisplay.size(); i++) {
-                final int id = mDozeStateByDisplay.keyAt(i);
-                final boolean dozed = mDozeStateByDisplay.valueAt(i);
-                pw.println("      " + id + " -> " + dozed);
+            synchronized (mSensorObserverLock) {
+                pw.println("    mIsProxActive=" + mIsProxActive);
+                pw.println("    mDozeStateByDisplay:");
+                for (int i = 0; i < mDozeStateByDisplay.size(); i++) {
+                    final int id = mDozeStateByDisplay.keyAt(i);
+                    final boolean dozed = mDozeStateByDisplay.valueAt(i);
+                    pw.println("      " + id + " -> " + dozed);
+                }
             }
         }
 
         @Override
         public void onDisplayAdded(int displayId) {
             boolean isDozeState = mInjector.isDozeState(mDisplayManager.getDisplay(displayId));
-            synchronized (mLock) {
+            synchronized (mSensorObserverLock) {
                 mDozeStateByDisplay.put(displayId, isDozeState);
                 recalculateVotesLocked();
             }
@@ -2217,7 +2222,7 @@ public class DisplayModeDirector {
         @Override
         public void onDisplayChanged(int displayId) {
             boolean wasDozeState = mDozeStateByDisplay.get(displayId);
-            synchronized (mLock) {
+            synchronized (mSensorObserverLock) {
                 mDozeStateByDisplay.put(displayId,
                         mInjector.isDozeState(mDisplayManager.getDisplay(displayId)));
                 if (wasDozeState != mDozeStateByDisplay.get(displayId)) {
@@ -2228,7 +2233,7 @@ public class DisplayModeDirector {
 
         @Override
         public void onDisplayRemoved(int displayId) {
-            synchronized (mLock) {
+            synchronized (mSensorObserverLock) {
                 mDozeStateByDisplay.delete(displayId);
                 recalculateVotesLocked();
             }