commit be0f948bd3b780e1a70e57eb01113ec897f99264
author Ady Abraham <adyabr@google.com> Wed Apr 24 15:41:53 2019 -0700
committer Ady Abraham <adyabr@google.com> Mon Apr 29 18:01:19 2019 -0700
tree 7670d86fdea1997faae5a87921e7b241cca65b9e
parent dde87c4a326d0480aef0420f04c160b9d5d5096e

SurfaceFlinger: support negative phase offset

Store the last 2 present frames to accommodate negative phase offsets.

Test: systrace
Bug: 130191039
Change-Id: Ie4460d4a1b14a2a12f5d2f3c1542e0b837cb761c

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 1d54cb2..5e0ba13 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -977,8 +977,7 @@
 bool SurfaceFlinger::performSetActiveConfig() {
     ATRACE_CALL();
     if (mCheckPendingFence) {
-        if (mPreviousPresentFence != Fence::NO_FENCE &&
-            (mPreviousPresentFence->getStatus() == Fence::Status::Unsignaled)) {
+        if (previousFrameMissed()) {
             // fence has not signaled yet. wait for the next invalidate
             repaintEverythingForHWC();
             return true;
@@ -1591,12 +1590,23 @@
     setTransactionFlags(eDisplayTransactionNeeded);
 }
 
+bool SurfaceFlinger::previousFrameMissed() NO_THREAD_SAFETY_ANALYSIS {
+    // We are storing the last 2 present fences. If sf's phase offset is to be
+    // woken up before the actual vsync but targeting the next vsync, we need to check
+    // fence N-2
+    const sp<Fence>& fence =
+            mVsyncModulator.getOffsets().sf < mPhaseOffsets->getOffsetThresholdForNextVsync()
+            ? mPreviousPresentFences[0]
+            : mPreviousPresentFences[1];
+
+    return fence != Fence::NO_FENCE && (fence->getStatus() == Fence::Status::Unsignaled);
+}
+
 void SurfaceFlinger::onMessageReceived(int32_t what) NO_THREAD_SAFETY_ANALYSIS {
     ATRACE_CALL();
     switch (what) {
         case MessageQueue::INVALIDATE: {
-            bool frameMissed = mPreviousPresentFence != Fence::NO_FENCE &&
-                    (mPreviousPresentFence->getStatus() == Fence::Status::Unsignaled);
+            bool frameMissed = previousFrameMissed();
             bool hwcFrameMissed = mHadDeviceComposition && frameMissed;
             bool gpuFrameMissed = mHadClientComposition && frameMissed;
             ATRACE_INT("FrameMissed", static_cast<int>(frameMissed));
@@ -1986,9 +1996,11 @@
     }
 
     getBE().mDisplayTimeline.updateSignalTimes();
-    mPreviousPresentFence = displayDevice ? getHwComposer().getPresentFence(*displayDevice->getId())
-                                          : Fence::NO_FENCE;
-    auto presentFenceTime = std::make_shared<FenceTime>(mPreviousPresentFence);
+    mPreviousPresentFences[1] = mPreviousPresentFences[0];
+    mPreviousPresentFences[0] = displayDevice
+            ? getHwComposer().getPresentFence(*displayDevice->getId())
+            : Fence::NO_FENCE;
+    auto presentFenceTime = std::make_shared<FenceTime>(mPreviousPresentFences[0]);
     getBE().mDisplayTimeline.push(presentFenceTime);
 
     DisplayStatInfo stats;
@@ -2079,7 +2091,7 @@
         }
     }
 
-    mTransactionCompletedThread.addPresentFence(mPreviousPresentFence);
+    mTransactionCompletedThread.addPresentFence(mPreviousPresentFences[0]);
     mTransactionCompletedThread.sendCallbacks();
 
     if (mLumaSampling && mRegionSamplingThread) {