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Commit 81835988 authored by Alec Mouri's avatar Alec Mouri
Browse files

Correct DispSync model when registering listeners 

* First event should be mapped to a predicted last event time
* Phase offset timing should be lock-step with the period update.

Bug: 124383894
Test: systrace
Change-Id: I742b30a8d28780a44592c4d3077f33d23cf65789
parent 75b0b621

services/surfaceflinger/Scheduler/DispSync.cpp

+20 −2
Original line number Diff line number Diff line
@@ -201,8 +201,26 @@ public: 
        listener.mCallback = callback;



        // We want to allow the firstmost future event to fire without

        // allowing any past events to fire

        listener.mLastEventTime = systemTime() - mPeriod / 2 + mPhase - mWakeupLatency;

        // allowing any past events to fire. To do this extrapolate from

        // mReferenceTime the most recent hardware vsync, and pin the

        // last event time there.

        const nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);

        if (mPeriod != 0) {

            const nsecs_t baseTime = now - mReferenceTime;

            const nsecs_t numPeriodsSinceReference = baseTime / mPeriod;

            const nsecs_t predictedReference = mReferenceTime + numPeriodsSinceReference * mPeriod;

            const nsecs_t phaseCorrection = mPhase + listener.mPhase;

            const nsecs_t predictedLastEventTime = predictedReference + phaseCorrection;

            if (predictedLastEventTime > now) {

                // Make sure that the last event time does not exceed the current time.

                // If it would, then back the last event time by a period.

                listener.mLastEventTime = predictedLastEventTime - mPeriod;

            } else {

                listener.mLastEventTime = predictedLastEventTime;

            }

        } else {

            listener.mLastEventTime = now + mPhase - mWakeupLatency;

        }



        mEventListeners.push_back(listener);