Log each time the layer stack changes for DisplayDevice.

Test: Manually note change in logcat.
Bug: 258910717
Change-Id: I2dc91f6c40afb91b3f0187c09be3c6639ae739b5

2 files changed, 7 insertions, 2 deletions

diff --git a/services/core/java/com/android/server/display/DisplayDevice.java b/services/core/java/com/android/server/display/DisplayDevice.java
index 76d71e2b968a..bb39307bdc0d 100644
--- a/services/core/java/com/android/server/display/DisplayDevice.java
+++ b/services/core/java/com/android/server/display/DisplayDevice.java
@@ -22,6 +22,7 @@ import android.graphics.Point;
 import android.graphics.Rect;
 import android.hardware.display.DisplayViewport;
 import android.os.IBinder;
+import android.util.Slog;
 import android.view.Display;
 import android.view.DisplayAddress;
 import android.view.Surface;
@@ -37,6 +38,7 @@ import java.io.PrintWriter;
  * </p>
  */
 abstract class DisplayDevice {
+    private static final String TAG = "DisplayDevice";
     private static final Display.Mode EMPTY_DISPLAY_MODE = new Display.Mode.Builder().build();
 
     private final DisplayAdapter mDisplayAdapter;
@@ -266,10 +268,13 @@ abstract class DisplayDevice {
     /**
      * Sets the display layer stack while in a transaction.
      */
-    public final void setLayerStackLocked(SurfaceControl.Transaction t, int layerStack) {
+    public final void setLayerStackLocked(SurfaceControl.Transaction t, int layerStack,
+            int layerStackTag) {
         if (mCurrentLayerStack != layerStack) {
             mCurrentLayerStack = layerStack;
             t.setDisplayLayerStack(mDisplayToken, layerStack);
+            Slog.i(TAG, "[" + layerStackTag + "] Layerstack set to " + layerStack + " for "
+                    + mUniqueId);
         }
     }
 
diff --git a/services/core/java/com/android/server/display/LogicalDisplay.java b/services/core/java/com/android/server/display/LogicalDisplay.java
index e6f27c1b0dd9..7dc412ed1cf8 100644
--- a/services/core/java/com/android/server/display/LogicalDisplay.java
+++ b/services/core/java/com/android/server/display/LogicalDisplay.java
@@ -494,7 +494,7 @@ final class LogicalDisplay {
             DisplayDevice device,
             boolean isBlanked) {
         // Set the layer stack.
-        device.setLayerStackLocked(t, isBlanked ? BLANK_LAYER_STACK : mLayerStack);
+        device.setLayerStackLocked(t, isBlanked ? BLANK_LAYER_STACK : mLayerStack, mDisplayId);
         // Also inform whether the device is the same one sent to inputflinger for its layerstack.
         // Prevent displays that are disabled from receiving input.
         // TODO(b/188914255): Remove once input can dispatch against device vs layerstack.