SF: wait instead of presenting early

If SurfaceFlinger duration is configured to a larger value
than the vsync period, there might be a chance that SF would
present the frame too early, if its actual duration is much shorter
than anticipating. To prevent this, we wait until the vsync occurs
before calling to hwc::present.

Bug: 185949581
Test: Configure large SF duration and observe systrace
Change-Id: Ic0c112a2808036d0f2e14a345c401fa56c2d29ab

7 files changed, 24 insertions, 0 deletions

diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/CompositionRefreshArgs.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/CompositionRefreshArgs.h
index a0606b48f0..289cb119ca 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/CompositionRefreshArgs.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/CompositionRefreshArgs.h
@@ -79,6 +79,9 @@ struct CompositionRefreshArgs {
 
     // If set, causes the dirty regions to flash with the delay
     std::optional<std::chrono::microseconds> devOptFlashDirtyRegionsDelay;
+
+    // The earliest time to send the present command to the HAL
+    std::chrono::steady_clock::time_point earliestPresentTime;
 };
 
 } // namespace android::compositionengine
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/OutputCompositionState.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/OutputCompositionState.h
index 8f767d37f6..f0ef6d6e7d 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/OutputCompositionState.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/OutputCompositionState.h
@@ -115,6 +115,9 @@ struct OutputCompositionState {
     // Current target dataspace
     ui::Dataspace targetDataspace{ui::Dataspace::UNKNOWN};
 
+    // The earliest time to send the present command to the HAL
+    std::chrono::steady_clock::time_point earliestPresentTime;
+
     // Debugging
     void dump(std::string& result) const;
 };
diff --git a/services/surfaceflinger/CompositionEngine/src/Display.cpp b/services/surfaceflinger/CompositionEngine/src/Display.cpp
index a605fe1dc3..1ffb1c8e2d 100644
--- a/services/surfaceflinger/CompositionEngine/src/Display.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Display.cpp
@@ -367,6 +367,11 @@ compositionengine::Output::FrameFences Display::presentAndGetFrameFences() {
         return fences;
     }
 
+    {
+        ATRACE_NAME("wait for earliest present time");
+        std::this_thread::sleep_until(getState().earliestPresentTime);
+    }
+
     auto& hwc = getCompositionEngine().getHwComposer();
     hwc.presentAndGetReleaseFences(*halDisplayIdOpt);
 
diff --git a/services/surfaceflinger/CompositionEngine/src/Output.cpp b/services/surfaceflinger/CompositionEngine/src/Output.cpp
index 3468b204fc..faa4b74c28 100644
--- a/services/surfaceflinger/CompositionEngine/src/Output.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/Output.cpp
@@ -711,6 +711,8 @@ void Output::writeCompositionState(const compositionengine::CompositionRefreshAr
         return;
     }
 
+    editState().earliestPresentTime = refreshArgs.earliestPresentTime;
+
     sp<GraphicBuffer> previousOverride = nullptr;
     for (auto* layer : getOutputLayersOrderedByZ()) {
         bool skipLayer = false;
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index 1d25c7247f..57bd045945 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -927,4 +927,11 @@ void Scheduler::setPreferredRefreshRateForUid(FrameRateOverride frameRateOverrid
     }
 }
 
+std::chrono::steady_clock::time_point Scheduler::getPreviousVsyncFrom(
+        nsecs_t expectedPresentTime) const {
+    const auto presentTime = std::chrono::nanoseconds(expectedPresentTime);
+    const auto vsyncPeriod = std::chrono::nanoseconds(mVsyncSchedule.tracker->currentPeriod());
+    return std::chrono::steady_clock::time_point(presentTime - vsyncPeriod);
+}
+
 } // namespace android
diff --git a/services/surfaceflinger/Scheduler/Scheduler.h b/services/surfaceflinger/Scheduler/Scheduler.h
index 4d1f3c6572..49d3d93f36 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.h
+++ b/services/surfaceflinger/Scheduler/Scheduler.h
@@ -149,6 +149,8 @@ public:
     bool isVsyncValid(nsecs_t expectedVsyncTimestamp, uid_t uid) const
             EXCLUDES(mFrameRateOverridesMutex);
 
+    std::chrono::steady_clock::time_point getPreviousVsyncFrom(nsecs_t expectedPresentTime) const;
+
     void dump(std::string&) const;
     void dump(ConnectionHandle, std::string&) const;
     void dumpVsync(std::string&) const;
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 7076124754..1e3402a72d 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1972,6 +1972,8 @@ void SurfaceFlinger::onMessageRefresh() {
                 std::chrono::milliseconds(mDebugRegion > 1 ? mDebugRegion : 0);
     }
 
+    refreshArgs.earliestPresentTime = mScheduler->getPreviousVsyncFrom(mExpectedPresentTime);
+
     mGeometryInvalid = false;
 
     // Store the present time just before calling to the composition engine so we could notify