From dafbfeadedc7fe04d15911645bb4424c061eaf79 Mon Sep 17 00:00:00 2001
From: Daniel Solomon <solomondaniel@google.com>
Date: Wed, 27 Apr 2022 01:13:29 +0000
Subject: [PATCH] Don't update brightness settings when throttling brightness

Currently, when brightness throttling is active it forces updating of
brightness settings. In some use cases, this causes settings to be
updated with values that are irrelevant to user settings (e.g., a
screen_brightness value of 1 when display is off).

To fix this, avoid updating settings as part of brightness throttling.
Instead, rely on the manual and auto brightness paths to trigger
settings updates when necessary.

Note that,
1. Brightness requested by manual and auto brightness is still
   throttled.
2. The throttled maximum brightness value and the final (throttled)
   display brightness are still broadcast accurately through values
   captured in BrightnessInfo.

Bug: 228286897
Test: atest BrightnessThrottlerTest AutomaticBrightnessControllerTest
Test: Manual:
    1. Disable auto brightness and set brightness to a high value
    2. Turn off the display
    3. Force thermal throttling (throttled brightness is >min)
    4. Turn on the display
    5. Verify that brightness is throttled and >min
Change-Id: I89bdcc2f77b6bf3b4b9b2fd7c1aa7b029dc9c174
---
 .../java/com/android/server/display/DisplayPowerController.java | 2 --
 1 file changed, 2 deletions(-)

diff --git a/services/core/java/com/android/server/display/DisplayPowerController.java b/services/core/java/com/android/server/display/DisplayPowerController.java
index 698f41f23e989..80ff8349a1538 100644
--- a/services/core/java/com/android/server/display/DisplayPowerController.java
+++ b/services/core/java/com/android/server/display/DisplayPowerController.java
@@ -1389,12 +1389,10 @@ final class DisplayPowerController implements AutomaticBrightnessController.Call
                 // Brightness throttling is needed, so do so quickly.
                 // Later, when throttling is removed, we let other mechanisms decide on speed.
                 slowChange = false;
-                updateScreenBrightnessSetting = true;
             }
             mAppliedThrottling = true;
         } else if (mAppliedThrottling) {
             mAppliedThrottling = false;
-            updateScreenBrightnessSetting = true;
         }
 
         if (updateScreenBrightnessSetting) {