DO NOT MERGE Extend mPreviousPresentFences for high refresh rate

To provide hardware enough time to display a frame under high refresh
rate with long sf-duration, we extend mPreviousPresentFences by storing
extra slots. We check proper present fence at different moment
according to vsync period and sf-duration.

Bug: 241193992
Change-Id: I618dd7abdb1f9ca2cb92623cc4d423389d62e402
(cherry picked from commit 1febfb87aadcdc59be95c0fd2d821ba89bc933ec)

2 files changed, 16 insertions, 4 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 38a067d1b3..c7c98107de 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -2170,8 +2170,17 @@ bool SurfaceFlinger::wouldPresentEarly(TimePoint frameTime, Period vsyncPeriod)
 auto SurfaceFlinger::getPreviousPresentFence(TimePoint frameTime, Period vsyncPeriod) const
         -> const FenceTimePtr& {
     const bool isTwoVsyncsAhead = mExpectedPresentTime - frameTime > vsyncPeriod;
-    const size_t i = static_cast<size_t>(isTwoVsyncsAhead);
-    return mPreviousPresentFences[i].fenceTime;
+
+    size_t shift = 0;
+    if (isTwoVsyncsAhead) {
+        shift = static_cast<size_t>(
+            Duration(mExpectedPresentTime - frameTime).ns() / vsyncPeriod.ns());
+        if (shift >= mPreviousPresentFences.size()) {
+            shift = mPreviousPresentFences.size() - 1;
+        }
+    }
+    ATRACE_FORMAT("previousFrameFence shift=%zu", shift);
+    return mPreviousPresentFences[shift].fenceTime;
 }
 
 bool SurfaceFlinger::isFencePending(const FenceTimePtr& fence, int graceTimeMs) {
@@ -2849,7 +2858,9 @@ void SurfaceFlinger::postComposition(nsecs_t callTime) {
         glCompositionDoneFenceTime = FenceTime::NO_FENCE;
     }
 
-    mPreviousPresentFences[1] = mPreviousPresentFences[0];
+    for (size_t i = mPreviousPresentFences.size()-1; i >= 1; i--) {
+        mPreviousPresentFences[i] = mPreviousPresentFences[i-1];
+    }
 
     auto presentFence = defaultDisplay
             ? getHwComposer().getPresentFence(defaultDisplay->getPhysicalId())
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 0bc506f1fe..be3a06ece7 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -1335,7 +1335,8 @@ private:
         sp<Fence> fence = Fence::NO_FENCE;
         FenceTimePtr fenceTime = FenceTime::NO_FENCE;
     };
-    std::array<FenceWithFenceTime, 2> mPreviousPresentFences;
+    // size should be longest sf-duration / shortest vsync period and round up
+    std::array<FenceWithFenceTime, 5> mPreviousPresentFences; // currently consider 166hz.
 
     TimePoint mScheduledPresentTime GUARDED_BY(kMainThreadContext);
     TimePoint mExpectedPresentTime GUARDED_BY(kMainThreadContext);