commit 8e3e2ea8a946c616140c1df06e395a62c724bacb
author Ady Abraham <adyabr@google.com> Thu Oct 31 15:52:31 2024 -0700
committer Ady Abraham <adyabr@google.com> Fri Nov 01 04:48:18 2024 +0000
tree c6435c1d10367c1171a3fb5fc3474516cce0f804
parent a8217b5de82897fdfb4a427643a1d1c851845e3a

SF: omit vsync callbacks when screen is OFF

This CL is submitted behind a flag and in still in development.
The flag should not be enabled just yet.

Test: manual
Bug: 331636736
Flag: com.android.graphics.surfaceflinger.flags.no_vsyncs_on_screen_off
Change-Id: Iec9cde3bafb9c112c9ce9beebe6dded4727fc99c

services/surfaceflinger/Scheduler/EventThread.cpp

diff --git a/services/surfaceflinger/Scheduler/EventThread.cpp b/services/surfaceflinger/Scheduler/EventThread.cpp
index e385f18..7729671 100644
--- a/services/surfaceflinger/Scheduler/EventThread.cpp
+++ b/services/surfaceflinger/Scheduler/EventThread.cpp
@@ -420,6 +420,16 @@
     mCondition.notify_all();
 }
 
+void EventThread::omitVsyncDispatching(bool omitted) {
+    std::lock_guard<std::mutex> lock(mMutex);
+    if (!mVSyncState || mVSyncState->omitted == omitted) {
+        return;
+    }
+
+    mVSyncState->omitted = omitted;
+    mCondition.notify_all();
+}
+
 void EventThread::onVsync(nsecs_t vsyncTime, nsecs_t wakeupTime, nsecs_t readyTime) {
     std::lock_guard<std::mutex> lock(mMutex);
     mLastVsyncCallbackTime = TimePoint::fromNs(vsyncTime);
@@ -521,7 +531,17 @@
         }
 
         if (mVSyncState && vsyncRequested) {
-            mState = mVSyncState->synthetic ? State::SyntheticVSync : State::VSync;
+            const bool vsyncOmitted =
+                    FlagManager::getInstance().no_vsyncs_on_screen_off() && mVSyncState->omitted;
+            if (vsyncOmitted) {
+                mState = State::Idle;
+                SFTRACE_INT("VsyncPendingScreenOn", 1);
+            } else {
+                mState = mVSyncState->synthetic ? State::SyntheticVSync : State::VSync;
+                if (FlagManager::getInstance().no_vsyncs_on_screen_off()) {
+                    SFTRACE_INT("VsyncPendingScreenOn", 0);
+                }
+            }
         } else {
             ALOGW_IF(!mVSyncState, "Ignoring VSYNC request while display is disconnected");
             mState = State::Idle;

services/surfaceflinger/Scheduler/EventThread.h

diff --git a/services/surfaceflinger/Scheduler/EventThread.h b/services/surfaceflinger/Scheduler/EventThread.h
index c3c7eb0..2daf126 100644
--- a/services/surfaceflinger/Scheduler/EventThread.h
+++ b/services/surfaceflinger/Scheduler/EventThread.h
@@ -106,6 +106,8 @@
     // Feed clients with fake VSYNC, e.g. while the display is off.
     virtual void enableSyntheticVsync(bool) = 0;
 
+    virtual void omitVsyncDispatching(bool) = 0;
+
     virtual void onHotplugReceived(PhysicalDisplayId displayId, bool connected) = 0;
 
     virtual void onHotplugConnectionError(int32_t connectionError) = 0;
@@ -165,6 +167,8 @@
 
     void enableSyntheticVsync(bool) override;
 
+    void omitVsyncDispatching(bool) override;
+
     void onHotplugReceived(PhysicalDisplayId displayId, bool connected) override;
 
     void onHotplugConnectionError(int32_t connectionError) override;
@@ -240,6 +244,9 @@
 
         // True if VSYNC should be faked, e.g. when display is off.
         bool synthetic = false;
+
+        // True if VSYNC should not be delivered to apps. Used when the display is off.
+        bool omitted = false;
     };
 
     // TODO(b/74619554): Create per-display threads waiting on respective VSYNC signals,

services/surfaceflinger/Scheduler/Scheduler.cpp

diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index b83ff19..b8b1f59 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -405,6 +405,14 @@
     eventThreadFor(Cycle::Render).enableSyntheticVsync(enable);
 }
 
+void Scheduler::omitVsyncDispatching(bool omitted) {
+    eventThreadFor(Cycle::Render).omitVsyncDispatching(omitted);
+    // Note: If we don't couple Cycle::LastComposite event thread, there is a black screen
+    // after boot. This is most likely sysui or system_server dependency on sf instance
+    // Choreographer
+    eventThreadFor(Cycle::LastComposite).omitVsyncDispatching(omitted);
+}
+
 void Scheduler::onFrameRateOverridesChanged() {
     const auto [pacesetterId, supportsFrameRateOverrideByContent] = [this] {
         std::scoped_lock lock(mDisplayLock);

services/surfaceflinger/Scheduler/Scheduler.h

diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index c88b563..d029488 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -154,6 +154,7 @@
     bool onDisplayModeChanged(PhysicalDisplayId, const FrameRateMode&) EXCLUDES(mPolicyLock);
 
     void enableSyntheticVsync(bool = true) REQUIRES(kMainThreadContext);
+    void omitVsyncDispatching(bool) REQUIRES(kMainThreadContext);
 
     void onHdcpLevelsChanged(Cycle, PhysicalDisplayId, int32_t, int32_t);