SF: pass a render rate to VsyncTracker instead of a divisor
passing a divisor to VsyncTracker might result in the wrong frame
rate when the vsync period is changing. The Divisor was calculated in
VsyncReactor which calculates it based on the new period, and passed
to VsyncTracker which might still be learning the new period, hence
using the old period.
Bug: 267780202
Test: SF unit tests
Change-Id: Ibb632d4ae6621a6ac0c0123e78f4c4d75699bd9e
diff --git a/services/surfaceflinger/Scheduler/Scheduler.cpp b/services/surfaceflinger/Scheduler/Scheduler.cpp
index 17cdff9..dab01ba 100644
--- a/services/surfaceflinger/Scheduler/Scheduler.cpp
+++ b/services/surfaceflinger/Scheduler/Scheduler.cpp
@@ -418,11 +418,7 @@
ALOGV("%s %s (%s)", __func__, to_string(mode.fps).c_str(),
to_string(mode.modePtr->getFps()).c_str());
- const auto divisor = RefreshRateSelector::getFrameRateDivisor(mode.modePtr->getFps(), mode.fps);
- LOG_ALWAYS_FATAL_IF(divisor == 0, "%s <> %s -- not divisors", to_string(mode.fps).c_str(),
- to_string(mode.fps).c_str());
-
- mVsyncSchedule->getTracker().setDivisor(static_cast<unsigned>(divisor));
+ mVsyncSchedule->getTracker().setRenderRate(renderFrameRate);
}
void Scheduler::resync() {
diff --git a/services/surfaceflinger/Scheduler/VSyncPredictor.cpp b/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
index 5a5afd8..de7b338 100644
--- a/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
+++ b/services/surfaceflinger/Scheduler/VSyncPredictor.cpp
@@ -272,13 +272,26 @@
// update the mLastVsyncSequence for reference point
mLastVsyncSequence = getVsyncSequenceLocked(timePoint);
- const auto mod = mLastVsyncSequence->seq % mDivisor;
- if (mod == 0) {
+ const auto renderRatePhase = [&]() REQUIRES(mMutex) -> int {
+ if (!mRenderRate) return 0;
+
+ const auto divisor =
+ RefreshRateSelector::getFrameRateDivisor(Fps::fromPeriodNsecs(mIdealPeriod),
+ *mRenderRate);
+ if (divisor <= 1) return 0;
+
+ const int mod = mLastVsyncSequence->seq % divisor;
+ if (mod == 0) return 0;
+
+ return divisor - mod;
+ }();
+
+ if (renderRatePhase == 0) {
return mLastVsyncSequence->vsyncTime;
}
auto const [slope, intercept] = getVSyncPredictionModelLocked();
- const auto approximateNextVsync = mLastVsyncSequence->vsyncTime + slope * (mDivisor - mod);
+ const auto approximateNextVsync = mLastVsyncSequence->vsyncTime + slope * renderRatePhase;
return nextAnticipatedVSyncTimeFromLocked(approximateNextVsync - slope / 2);
}
@@ -317,10 +330,10 @@
return vsyncSequence.seq % divisor == 0;
}
-void VSyncPredictor::setDivisor(unsigned divisor) {
- ALOGV("%s: %d", __func__, divisor);
+void VSyncPredictor::setRenderRate(Fps fps) {
+ ALOGV("%s: %s", __func__, to_string(fps).c_str());
std::lock_guard lock(mMutex);
- mDivisor = divisor;
+ mRenderRate = fps;
}
VSyncPredictor::Model VSyncPredictor::getVSyncPredictionModel() const {
diff --git a/services/surfaceflinger/Scheduler/VSyncPredictor.h b/services/surfaceflinger/Scheduler/VSyncPredictor.h
index d0e3098..cd5d9ef 100644
--- a/services/surfaceflinger/Scheduler/VSyncPredictor.h
+++ b/services/surfaceflinger/Scheduler/VSyncPredictor.h
@@ -67,7 +67,7 @@
bool isVSyncInPhase(nsecs_t timePoint, Fps frameRate) const final EXCLUDES(mMutex);
- void setDivisor(unsigned divisor) final EXCLUDES(mMutex);
+ void setRenderRate(Fps) final EXCLUDES(mMutex);
void dump(std::string& result) const final EXCLUDES(mMutex);
@@ -106,7 +106,7 @@
size_t mLastTimestampIndex GUARDED_BY(mMutex) = 0;
std::vector<nsecs_t> mTimestamps GUARDED_BY(mMutex);
- unsigned mDivisor GUARDED_BY(mMutex) = 1;
+ std::optional<Fps> mRenderRate GUARDED_BY(mMutex);
mutable std::optional<VsyncSequence> mLastVsyncSequence GUARDED_BY(mMutex);
};
diff --git a/services/surfaceflinger/Scheduler/VSyncTracker.h b/services/surfaceflinger/Scheduler/VSyncTracker.h
index 8d1629f..bc0e3bc 100644
--- a/services/surfaceflinger/Scheduler/VSyncTracker.h
+++ b/services/surfaceflinger/Scheduler/VSyncTracker.h
@@ -80,15 +80,16 @@
virtual bool isVSyncInPhase(nsecs_t timePoint, Fps frameRate) const = 0;
/*
- * Sets a divisor on the rate (which is a multiplier of the period).
+ * Sets a render rate on the tracker. If the render rate is not a divisor
+ * of the period, the render rate is ignored until the period changes.
* The tracker will continue to track the vsync timeline and expect it
* to match the current period, however, nextAnticipatedVSyncTimeFrom will
- * return vsyncs according to the divisor set. Setting a divisor is useful
+ * return vsyncs according to the render rate set. Setting a render rate is useful
* when a display is running at 120Hz but the render frame rate is 60Hz.
*
- * \param [in] divisor The rate divisor the tracker should operate at.
+ * \param [in] Fps The render rate the tracker should operate at.
*/
- virtual void setDivisor(unsigned divisor) = 0;
+ virtual void setRenderRate(Fps) = 0;
virtual void dump(std::string& result) const = 0;