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Commit e6ad1602 authored by Alec Mouri's avatar Alec Mouri Committed by Ana Krulec
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[SurfaceFlinger] Exclude first vsync duration from period calculation 

Some displays don't exit from idle state immediately when vsync is
enabled through the kernel idle timer, so exclude the first vsync period
instead of just the first sample.

Bug: 136197211
Test: Scrolling through settings
Change-Id: I899fec289c8b08cfaa3264f7f6291a6fac489ab8
(cherry picked from commit 94390a32)
Merged-In: I899fec289c8b08cfaa3264f7f6291a6fac489ab8
parent 3a123024

services/surfaceflinger/Scheduler/DispSync.cpp

+11 −6
Original line number Diff line number Diff line
@@ -668,7 +668,13 @@ void DispSync::updateModelLocked() { 
        nsecs_t durationSum = 0;

        nsecs_t minDuration = INT64_MAX;

        nsecs_t maxDuration = 0;

        for (size_t i = 1; i < mNumResyncSamples; i++) {

        // We skip the first 2 samples because the first vsync duration on some

        // devices may be much more inaccurate than on other devices, e.g. due

        // to delays in ramping up from a power collapse. By doing so this

        // actually increases the accuracy of the DispSync model even though

        // we're effectively relying on fewer sample points.

        static constexpr size_t numSamplesSkipped = 2;

        for (size_t i = numSamplesSkipped; i < mNumResyncSamples; i++) {

            size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;

            size_t prev = (idx + MAX_RESYNC_SAMPLES - 1) % MAX_RESYNC_SAMPLES;

            nsecs_t duration = mResyncSamples[idx] - mResyncSamples[prev];
@@ -679,15 +685,14 @@ void DispSync::updateModelLocked() { 


        // Exclude the min and max from the average

        durationSum -= minDuration + maxDuration;

        mPeriod = durationSum / (mNumResyncSamples - 3);

        mPeriod = durationSum / (mNumResyncSamples - numSamplesSkipped - 2);



        ALOGV("[%s] mPeriod = %" PRId64, mName, ns2us(mPeriod));



        double sampleAvgX = 0;

        double sampleAvgY = 0;

        double scale = 2.0 * M_PI / double(mPeriod);

        // Intentionally skip the first sample

        for (size_t i = 1; i < mNumResyncSamples; i++) {

        for (size_t i = numSamplesSkipped; i < mNumResyncSamples; i++) {

            size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;

            nsecs_t sample = mResyncSamples[idx] - mReferenceTime;

            double samplePhase = double(sample % mPeriod) * scale;
@@ -695,8 +700,8 @@ void DispSync::updateModelLocked() { 
            sampleAvgY += sin(samplePhase);

        }



        sampleAvgX /= double(mNumResyncSamples - 1);

        sampleAvgY /= double(mNumResyncSamples - 1);

        sampleAvgX /= double(mNumResyncSamples - numSamplesSkipped);

        sampleAvgY /= double(mNumResyncSamples - numSamplesSkipped);



        mPhase = nsecs_t(atan2(sampleAvgY, sampleAvgX) / scale);