commit 676b1f6ed0d637b7eb1858361e0d09068f26e9fa
author Haixia Shi <hshi@google.com> Wed Oct 28 16:19:01 2015 -0700
committer Haixia Shi <hshi@google.com> Fri Oct 30 13:16:33 2015 -0700
tree 3c10e0560a60afa533ba7d28ba066a0ee4208047
parent 664339a8e8d3f2d5acd5728dae666cc9a14e08f3

SF: more DispSync improvements.

Pass the reference time to DispSyncThread. Since the phase offset is calculated
using timestamps relative to the reference time, we must also adjust the phase
offset by the same reference time when computing the next refresh time.

Always reset phase offset to zero when updating the reference time because the
reference time equals the first timestamp.

After beginResync() we need to keep HW vsync enabled until the model is updated.

Bug: 25113115
Change-Id: I8eae227bee91c24a99bf8e57fbebceb98d29c77d
Test: check in systrace that app/sf vsync events have correct phase

services/surfaceflinger/DispSync.cpp

diff --git a/services/surfaceflinger/DispSync.cpp b/services/surfaceflinger/DispSync.cpp
index a342dfe..5ba387d 100644
--- a/services/surfaceflinger/DispSync.cpp
+++ b/services/surfaceflinger/DispSync.cpp
@@ -56,15 +56,17 @@
             mStop(false),
             mPeriod(0),
             mPhase(0),
+            mReferenceTime(0),
             mWakeupLatency(0) {
     }
 
     virtual ~DispSyncThread() {}
 
-    void updateModel(nsecs_t period, nsecs_t phase) {
+    void updateModel(nsecs_t period, nsecs_t phase, nsecs_t referenceTime) {
         Mutex::Autolock lock(mMutex);
         mPeriod = period;
         mPhase = phase;
+        mReferenceTime = referenceTime;
         mCond.signal();
     }
 
@@ -246,7 +248,7 @@
             ref = lastEventTime;
         }
 
-        nsecs_t phase = mPhase + listener.mPhase;
+        nsecs_t phase = mReferenceTime + mPhase + listener.mPhase;
         nsecs_t t = (((ref - phase) / mPeriod) + 1) * mPeriod + phase;
 
         if (t - listener.mLastEventTime < mPeriod / 2) {
@@ -266,6 +268,7 @@
 
     nsecs_t mPeriod;
     nsecs_t mPhase;
+    nsecs_t mReferenceTime;
     nsecs_t mWakeupLatency;
 
     Vector<EventListener> mEventListeners;
@@ -313,9 +316,11 @@
 void DispSync::reset() {
     Mutex::Autolock lock(mMutex);
 
+    mPhase = 0;
+    mReferenceTime = 0;
+    mModelUpdated = false;
     mNumResyncSamples = 0;
     mFirstResyncSample = 0;
-    mResyncReferenceTime = 0;
     mNumResyncSamplesSincePresent = 0;
     resetErrorLocked();
 }
@@ -341,12 +346,13 @@
 
     updateErrorLocked();
 
-    return mPeriod == 0 || mError > kErrorThreshold;
+    return !mModelUpdated || mError > kErrorThreshold;
 }
 
 void DispSync::beginResync() {
     Mutex::Autolock lock(mMutex);
 
+    mModelUpdated = false;
     mNumResyncSamples = 0;
 }
 
@@ -356,7 +362,8 @@
     size_t idx = (mFirstResyncSample + mNumResyncSamples) % MAX_RESYNC_SAMPLES;
     mResyncSamples[idx] = timestamp;
     if (mNumResyncSamples == 0) {
-        mResyncReferenceTime = timestamp;
+        mPhase = 0;
+        mReferenceTime = timestamp;
     }
 
     if (mNumResyncSamples < MAX_RESYNC_SAMPLES) {
@@ -380,7 +387,7 @@
         return mThread->hasAnyEventListeners();
     }
 
-    return mPeriod == 0 || mError > kErrorThreshold;
+    return !mModelUpdated || mError > kErrorThreshold;
 }
 
 void DispSync::endResync() {
@@ -409,7 +416,8 @@
     Mutex::Autolock lock(mMutex);
     mPeriod = period;
     mPhase = 0;
-    mThread->updateModel(mPeriod, mPhase);
+    mReferenceTime = 0;
+    mThread->updateModel(mPeriod, mPhase, mReferenceTime);
 }
 
 nsecs_t DispSync::getPeriod() {
@@ -434,7 +442,7 @@
         double scale = 2.0 * M_PI / double(mPeriod);
         for (size_t i = 0; i < mNumResyncSamples; i++) {
             size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;
-            nsecs_t sample = mResyncSamples[idx] - mResyncReferenceTime;
+            nsecs_t sample = mResyncSamples[idx] - mReferenceTime;
             double samplePhase = double(sample % mPeriod) * scale;
             sampleAvgX += cos(samplePhase);
             sampleAvgY += sin(samplePhase);
@@ -457,12 +465,13 @@
         // Artificially inflate the period if requested.
         mPeriod += mPeriod * mRefreshSkipCount;
 
-        mThread->updateModel(mPeriod, mPhase);
+        mThread->updateModel(mPeriod, mPhase, mReferenceTime);
+        mModelUpdated = true;
     }
 }
 
 void DispSync::updateErrorLocked() {
-    if (mPeriod == 0) {
+    if (!mModelUpdated) {
         return;
     }
 
@@ -474,7 +483,7 @@
     nsecs_t sqErrSum = 0;
 
     for (size_t i = 0; i < NUM_PRESENT_SAMPLES; i++) {
-        nsecs_t sample = mPresentTimes[i] - mResyncReferenceTime;
+        nsecs_t sample = mPresentTimes[i] - mReferenceTime;
         if (sample > mPhase) {
             nsecs_t sampleErr = (sample - mPhase) % period;
             if (sampleErr > period / 2) {
@@ -508,7 +517,8 @@
 nsecs_t DispSync::computeNextRefresh(int periodOffset) const {
     Mutex::Autolock lock(mMutex);
     nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
-    return (((now - mPhase) / mPeriod) + periodOffset + 1) * mPeriod + mPhase;
+    nsecs_t phase = mReferenceTime + mPhase;
+    return (((now - phase) / mPeriod) + periodOffset + 1) * mPeriod + phase;
 }
 
 void DispSync::dump(String8& result) const {