commit 9e88d62f9045bbc87905892f44f2b7ebc2a72831
author Dominik Laskowski <domlaskowski@google.com> Wed Mar 06 17:42:39 2024 -0500
committer Dominik Laskowski <domlaskowski@google.com> Tue Mar 19 10:34:02 2024 -0400
tree 4afe236343a051bea586058355bb2f16a1c73f64
parent 703c1c04d8ec04619604239458bd8b2c3517742d

SF: Match followers' refresh rate to pacesetter's

Multi-display refresh rate selection was flawed: The scheduler runs the
refresh rate selection algorithm for each display, and then filters the
candidate modes of each follower to match the pacesetter's refresh rate.

This means that:

1. The followers incorrectly consider refresh rates that don't match the
   pacesetter. Because the DM-specified constraint is [59, 61] Hz, some
   situations caused selection of a fractional rate (e.g. 59.94) instead
   of 60 on certain external displays. The result would be black screens
   for several seconds due to mode sets if the selection was not stable.

2. The followers incorrectly evaluate heuristics that should only affect
   the pacesetter, e.g. per-surface votes, global signals.

Fix this by teaching RefreshRateSelector about follower displays.

Foldables also benefit from no longer running the algorithm twice.

Fixes: 324188430
Bug: 329111930
Test: No black screen for 4 seconds upon rotating mirrored YouTube.
Test: 60+60 still works on foldables.
Test: RefreshRateSelectorTest.pacesetterConsidered
Change-Id: Ie1b27e81d860a709c85651f068fedb2b496861de

services/surfaceflinger/tests/unittests/SchedulerTest.cpp

diff --git a/services/surfaceflinger/tests/unittests/SchedulerTest.cpp b/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
index d4735c7..8ac8eda 100644
--- a/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
@@ -362,7 +362,7 @@
                                                   globalSignals)(kDisplayId2,
                                                                  FrameRateMode{60_Hz,
                                                                                kDisplay2Mode60},
-                                                                 globalSignals);
+                                                                 GlobalSignals{});
 
         std::vector<RefreshRateSelector::LayerRequirement> layers = {{.weight = 1.f},
                                                                      {.weight = 1.f}};
@@ -381,7 +381,7 @@
                                                   globalSignals)(kDisplayId2,
                                                                  FrameRateMode{120_Hz,
                                                                                kDisplay2Mode120},
-                                                                 globalSignals);
+                                                                 GlobalSignals{});
 
         mScheduler->setTouchStateAndIdleTimerPolicy(globalSignals);
 
@@ -400,7 +400,7 @@
                                                   globalSignals)(kDisplayId2,
                                                                  FrameRateMode{120_Hz,
                                                                                kDisplay2Mode120},
-                                                                 globalSignals);
+                                                                 GlobalSignals{});
 
         const auto actualChoices = mScheduler->chooseDisplayModes();
         EXPECT_EQ(expectedChoices, actualChoices);
@@ -422,10 +422,10 @@
                 DisplayModeChoice>(kDisplayId1, FrameRateMode{120_Hz, kDisplay1Mode120},
                                    globalSignals)(kDisplayId2,
                                                   FrameRateMode{120_Hz, kDisplay2Mode120},
-                                                  globalSignals)(kDisplayId3,
-                                                                 FrameRateMode{60_Hz,
-                                                                               kDisplay3Mode60},
-                                                                 globalSignals);
+                                                  GlobalSignals{})(kDisplayId3,
+                                                                   FrameRateMode{60_Hz,
+                                                                                 kDisplay3Mode60},
+                                                                   GlobalSignals{});
 
         const auto actualChoices = mScheduler->chooseDisplayModes();
         EXPECT_EQ(expectedChoices, actualChoices);
@@ -440,12 +440,12 @@
         expectedChoices = ftl::init::map<
                 const PhysicalDisplayId&,
                 DisplayModeChoice>(kDisplayId1, FrameRateMode{60_Hz, kDisplay1Mode60},
-                                   globalSignals)(kDisplayId2,
-                                                  FrameRateMode{60_Hz, kDisplay2Mode60},
-                                                  globalSignals)(kDisplayId3,
-                                                                 FrameRateMode{60_Hz,
-                                                                               kDisplay3Mode60},
-                                                                 globalSignals);
+                                   GlobalSignals{})(kDisplayId2,
+                                                    FrameRateMode{60_Hz, kDisplay2Mode60},
+                                                    GlobalSignals{})(kDisplayId3,
+                                                                     FrameRateMode{60_Hz,
+                                                                                   kDisplay3Mode60},
+                                                                     globalSignals);
 
         const auto actualChoices = mScheduler->chooseDisplayModes();
         EXPECT_EQ(expectedChoices, actualChoices);