commit 11b6a70c6f6780f2f878ed3e103b5ffbb0b8fc26
author Ady Abraham <adyabr@google.com> Thu Jun 27 11:24:19 2019 -0700
committer Ady Abraham <adyabr@google.com> Wed Jul 10 10:47:38 2019 -0700
tree 3b71ecbb459e0d3a42c9bad2e7ffbf1e57bef3c8
parent 42b3beb51f7f3e97762ed1db7ebc0decbfa56bb4

SurfaceFlinger: correct negative offset when refresh rate changes

VsyncModulator sets the phase offset on DispSync source only when it
changes. However, negative offsets depends on the vsync period so setting
the same negative offset might result in a different wake up time
i.e. -5ms on 60Hz is 11ms after the previous vsync where on 90Hz is
6ms after the previous vsync.

Test: UI-Bench
Bug: 135283780
Bug: 135297302
Change-Id: I6a05cd48d563a51d2ee38927c23d4946dd142f4b

services/surfaceflinger/Scheduler/DispSyncSource.cpp

diff --git a/services/surfaceflinger/Scheduler/DispSyncSource.cpp b/services/surfaceflinger/Scheduler/DispSyncSource.cpp
index 026b557..5faf46e 100644
--- a/services/surfaceflinger/Scheduler/DispSyncSource.cpp
+++ b/services/surfaceflinger/Scheduler/DispSyncSource.cpp
@@ -78,6 +78,10 @@
     // Normalize phaseOffset to [-period, period)
     const int numPeriods = phaseOffset / period;
     phaseOffset -= numPeriods * period;
+    if (mPhaseOffset == phaseOffset) {
+        return;
+    }
+
     mPhaseOffset = phaseOffset;
     tracePhaseOffset();
 

services/surfaceflinger/Scheduler/VSyncModulator.cpp

diff --git a/services/surfaceflinger/Scheduler/VSyncModulator.cpp b/services/surfaceflinger/Scheduler/VSyncModulator.cpp
index d452c19..7a3bf8e 100644
--- a/services/surfaceflinger/Scheduler/VSyncModulator.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncModulator.cpp
@@ -129,29 +129,16 @@
 
 void VSyncModulator::updateOffsetsLocked() {
     const Offsets desired = getNextOffsets();
-    const Offsets current = mOffsets;
 
-    bool changed = false;
-    if (desired.sf != current.sf) {
-        if (mSfConnectionHandle != nullptr) {
-            mScheduler->setPhaseOffset(mSfConnectionHandle, desired.sf);
-        } else if (mSfEventThread != nullptr) {
-            mSfEventThread->setPhaseOffset(desired.sf);
-        }
-        changed = true;
-    }
-    if (desired.app != current.app) {
-        if (mAppConnectionHandle != nullptr) {
-            mScheduler->setPhaseOffset(mAppConnectionHandle, desired.app);
-        } else if (mAppEventThread != nullptr) {
-            mAppEventThread->setPhaseOffset(desired.app);
-        }
-        changed = true;
+    if (mSfConnectionHandle != nullptr) {
+        mScheduler->setPhaseOffset(mSfConnectionHandle, desired.sf);
     }
 
-    if (changed) {
-        flushOffsets();
+    if (mAppConnectionHandle != nullptr) {
+        mScheduler->setPhaseOffset(mAppConnectionHandle, desired.app);
     }
+
+    flushOffsets();
 }
 
 void VSyncModulator::flushOffsets() {

services/surfaceflinger/Scheduler/VSyncModulator.h

diff --git a/services/surfaceflinger/Scheduler/VSyncModulator.h b/services/surfaceflinger/Scheduler/VSyncModulator.h
index 10cf8e6..ddbd221 100644
--- a/services/surfaceflinger/Scheduler/VSyncModulator.h
+++ b/services/surfaceflinger/Scheduler/VSyncModulator.h
@@ -68,12 +68,6 @@
     void setPhaseOffsets(Offsets early, Offsets earlyGl, Offsets late,
                          nsecs_t thresholdForNextVsync) EXCLUDES(mMutex);
 
-    // Sets handles to the SF and app event threads.
-    void setEventThreads(EventThread* sfEventThread, EventThread* appEventThread) {
-        mSfEventThread = sfEventThread;
-        mAppEventThread = appEventThread;
-    }
-
     // Sets the scheduler and vsync connection handlers.
     void setSchedulerAndHandles(Scheduler* scheduler,
                                 Scheduler::ConnectionHandle* appConnectionHandle,
@@ -121,9 +115,6 @@
     std::unordered_map<OffsetType, Offsets> mOffsetMap GUARDED_BY(mMutex);
     nsecs_t mThresholdForNextVsync;
 
-    EventThread* mSfEventThread = nullptr;
-    EventThread* mAppEventThread = nullptr;
-
     Scheduler* mScheduler = nullptr;
     Scheduler::ConnectionHandle* mAppConnectionHandle = nullptr;
     Scheduler::ConnectionHandle* mSfConnectionHandle = nullptr;