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Commit bb4e3baf authored by Alec Mouri's avatar Alec Mouri
Browse files

Fix up reference times for period changes. 

* When the model is reset, use the last seen reference time instead
of 0, since the reference time of 0 is guaranteed to yield inaccurate
pulses.
* When the DispSync model is updated, reduce the reference time by a
period to derisk spurious events firing when the model is updated.

Bug: 124383894
Test: systrace
Change-Id: Idb7fd5a9bacdd78133ab6451b5a79789a32e339e
parent 066bd7e0

services/surfaceflinger/Scheduler/DispSync.cpp

+19 −3
Original line number Diff line number Diff line
@@ -76,9 +76,18 @@ public: 
    void updateModel(nsecs_t period, nsecs_t phase, nsecs_t referenceTime) {

        if (mTraceDetailedInfo) ATRACE_CALL();

        Mutex::Autolock lock(mMutex);

        mPeriod = period;



        mPhase = phase;

        mReferenceTime = referenceTime;

        if (mPeriod != period && mReferenceTime != 0) {

            // Inflate the reference time to be the most recent predicted

            // vsync before the current time.

            const nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);

            const nsecs_t baseTime = now - mReferenceTime;

            const nsecs_t numOldPeriods = baseTime / mPeriod;

            mReferenceTime = mReferenceTime + (numOldPeriods)*mPeriod;

        }

        mPeriod = period;

        if (mTraceDetailedInfo) {

            ATRACE_INT64("DispSync:Period", mPeriod);

            ATRACE_INT64("DispSync:Phase", mPhase + mPeriod / 2);
@@ -429,8 +438,16 @@ void DispSync::reset() { 


void DispSync::resetLocked() {

    mPhase = 0;

    mReferenceTime = 0;

    const size_t lastSampleIdx = (mFirstResyncSample + mNumResyncSamples - 1) % MAX_RESYNC_SAMPLES;

    // Keep the most recent sample, when we resync to hardware we'll overwrite this

    // with a more accurate signal

    if (mResyncSamples[lastSampleIdx] != 0) {

        mReferenceTime = mResyncSamples[lastSampleIdx];

    }

    mModelUpdated = false;

    for (size_t i = 0; i < MAX_RESYNC_SAMPLES; i++) {

        mResyncSamples[i] = 0;

    }

    mNumResyncSamples = 0;

    mFirstResyncSample = 0;

    mNumResyncSamplesSincePresent = 0;
@@ -530,7 +547,6 @@ void DispSync::setPeriod(nsecs_t period) { 
    Mutex::Autolock lock(mMutex);

    mPeriod = period;

    mPhase = 0;

    mReferenceTime = 0;

    mThread->updateModel(mPeriod, mPhase, mReferenceTime);

}

services/surfaceflinger/Scheduler/DispSync.h

+1 −1
Original line number Diff line number Diff line
@@ -213,7 +213,7 @@ private: 
    // These member variables are the state used during the resynchronization

    // process to store information about the hardware vsync event times used

    // to compute the model.

    nsecs_t mResyncSamples[MAX_RESYNC_SAMPLES];

    nsecs_t mResyncSamples[MAX_RESYNC_SAMPLES] = {0};

    size_t mFirstResyncSample;

    size_t mNumResyncSamples;

    int mNumResyncSamplesSincePresent;