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

2 files changed, 16 insertions, 4 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 6a17cd8881..e9fbf6ea7b 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1955,8 +1955,16 @@ SurfaceFlinger::FenceWithFenceTime SurfaceFlinger::previousFrameFence() {
     const auto now = systemTime();
     const auto vsyncPeriod = mScheduler->getDisplayStatInfo(now).vsyncPeriod;
     const bool expectedPresentTimeIsTheNextVsync = mExpectedPresentTime - now <= vsyncPeriod;
-    return expectedPresentTimeIsTheNextVsync ? mPreviousPresentFences[0]
-                                             : mPreviousPresentFences[1];
+
+    size_t shift = 0;
+    if (!expectedPresentTimeIsTheNextVsync) {
+        shift = static_cast<size_t>((mExpectedPresentTime - now) / vsyncPeriod);
+        if (shift >= mPreviousPresentFences.size()) {
+            shift = mPreviousPresentFences.size() - 1;
+        }
+    }
+    ATRACE_FORMAT("previousFrameFence shift=%zu", shift);
+    return mPreviousPresentFences[shift];
 }
 
 bool SurfaceFlinger::previousFramePending(int graceTimeMs) {
@@ -2425,7 +2433,10 @@ void SurfaceFlinger::postComposition() {
         glCompositionDoneFenceTime = FenceTime::NO_FENCE;
     }
 
-    mPreviousPresentFences[1] = mPreviousPresentFences[0];
+    for (size_t i = mPreviousPresentFences.size()-1; i >= 1; i--) {
+        mPreviousPresentFences[i] = mPreviousPresentFences[i-1];
+    }
+
     mPreviousPresentFences[0].fence =
             display ? getHwComposer().getPresentFence(display->getPhysicalId()) : Fence::NO_FENCE;
     mPreviousPresentFences[0].fenceTime =
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index f14c755c2b..46f0e6ba83 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -1224,7 +1224,8 @@ private:
     std::unordered_set<sp<Layer>, SpHash<Layer>> mLayersWithQueuedFrames;
     // Tracks layers that need to update a display's dirty region.
     std::vector<sp<Layer>> mLayersPendingRefresh;
-    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.
     // True if in the previous frame at least one layer was composed via the GPU.
     bool mHadClientComposition = false;
     // True if in the previous frame at least one layer was composed via HW Composer.