From f18a9641e6d1e7d7b8014ed207f74a4971c78ffa Mon Sep 17 00:00:00 2001
From: Robin Lee <rgl@google.com>
Date: Wed, 20 Jan 2021 00:20:47 +0100
Subject: [PATCH] Don't recompute display mode during a mode switch

When an app requests a display mode change, it's plausible that the next
thing to happen is going to be a configuration change.

During the configuration change, multiple windows that contributed to
the selection of the display mode will no longer be displayed. This can
lead to a device bouncing between two display modes for a while.

We need to wait for windows to redraw and for the screen to unfreeze
again before we next call DisplayManagerService.setDisplayProperties.

Test: atest android.display.cts.DisplayTest
Bug: 158316271
Change-Id: I58e4626e74a911a14cbcd426d1f09ef68303dafa
---
 .../java/com/android/server/wm/DisplayContent.java | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/services/core/java/com/android/server/wm/DisplayContent.java b/services/core/java/com/android/server/wm/DisplayContent.java
index 73bcf47979fe2..a4c0762f8f924 100644
--- a/services/core/java/com/android/server/wm/DisplayContent.java
+++ b/services/core/java/com/android/server/wm/DisplayContent.java
@@ -4185,12 +4185,14 @@ class DisplayContent extends RootDisplayArea implements WindowManagerPolicy.Disp
         mInsetsStateController.getImeSourceProvider().checkShowImePostLayout();
 
         mLastHasContent = mTmpApplySurfaceChangesTransactionState.displayHasContent;
-        mWmService.mDisplayManagerInternal.setDisplayProperties(mDisplayId,
-                mLastHasContent,
-                mTmpApplySurfaceChangesTransactionState.preferredRefreshRate,
-                mTmpApplySurfaceChangesTransactionState.preferredModeId,
-                mTmpApplySurfaceChangesTransactionState.preferMinimalPostProcessing,
-                true /* inTraversal, must call performTraversalInTrans... below */);
+        if (!mWmService.mDisplayFrozen) {
+            mWmService.mDisplayManagerInternal.setDisplayProperties(mDisplayId,
+                    mLastHasContent,
+                    mTmpApplySurfaceChangesTransactionState.preferredRefreshRate,
+                    mTmpApplySurfaceChangesTransactionState.preferredModeId,
+                    mTmpApplySurfaceChangesTransactionState.preferMinimalPostProcessing,
+                    true /* inTraversal, must call performTraversalInTrans... below */);
+        }
 
         final boolean wallpaperVisible = mWallpaperController.isWallpaperVisible();
         if (wallpaperVisible != mLastWallpaperVisible) {