android P-sensor (Proximity Sensor)

P-sensor (Proximity Sensor) 手机接听电话时，贴近屏幕时，屏幕会灭屏，以防止脸部触碰屏幕引起误操作。当我们的脸离开屏幕时，屏幕会自动亮屏. phone app(maybe incallUI) 会申请 wakeLock（ PROXIMITY_SCREEN_OFF_WAKE_LOCK）     wakeLock =context.getSystemService(PowerManager.class)
                .newWakeLock(PowerManager.PROXIMITY_SCREEN_OFF_WAKE_LOCK, TAG);     wakeLock.acquire();   //通话时候会acquire 这个wakeLock， framework会enable p-sensor
    wakeLock.release(); //通话结束时会释放这个wakeLock， framework 会 disable p-sensor
主要code： base\services\core\java\com\android\server\display\DisplayPowerController.java base\services\core\java\com\android\server\power\PowerManagerService.java 大致的工作流程是： acquire()                         --PowerManager.java acquireLocked() acquireWakeLock()                 --PowerManagerService.java acquireWakeLockInternal()   updatePowerStateLocked() updateDisplayPowerStateLocked()     private boolean updateDisplayPowerStateLocked(int dirty) {         ......              //p-sensor wakeLock acquire后，useProximitySensor为true; release后useProximitySensor为false
            mDisplayPowerRequest. useProximitySensor = shouldUseProximitySensorLocked();
        ......             mDisplayReady = mDisplayManagerInternal. requestPowerState(mDisplayPowerRequest,
                    mRequestWaitForNegativeProximity); requestPowerState()                --DisplayManagerService.java requestPowerState()                --DisplayPowerController.java sendUpdatePowerStateLocked() MSG_UPDATE_POWER_STATE handleMessage()                      updatePowerState()     private void updatePowerState() { // 更新屏幕状态         ......          // 根据当前状态enable/disable p-Sensor         // Apply the proximity sensor.
        if (mProximitySensor != null) {
            if (mPowerRequest. useProximitySensor && state != Display.STATE_OFF) {
                setProximitySensorEnabled(true); //enable p-Sensor
                if (!mScreenOffBecauseOfProximity
                        && mProximity == PROXIMITY_POSITIVE) {                     mScreenOffBecauseOfProximity = true; //p-Sensor 遮挡, 屏幕暗掉
                    sendOnProximityPositiveWithWakelock();
                }
            } else if (mWaitingForNegativeProximity
                    && mScreenOffBecauseOfProximity
                    && mProximity == PROXIMITY_POSITIVE
                    && state != Display.STATE_OFF) {
                setProximitySensorEnabled(true); //enable on p-Sensor
            } else {
                setProximitySensorEnabled(false); // disable off p-Sensor, 屏幕亮起
                mWaitingForNegativeProximity = false;
            }
            if (mScreenOffBecauseOfProximity
                    && mProximity != PROXIMITY_POSITIVE) {
                mScreenOffBecauseOfProximity = false;  // p-Sensor 没用遮挡, 起作用
                sendOnProximityNegativeWithWakelock();
            }
        } else {
            mWaitingForNegativeProximity = false;
        }         if ( mScreenOffBecauseOfProximity) {   // p_Sensor 遮挡， screen off
            state = Display.STATE_OFF;
        }         // Use zero brightness when screen is off.
        if ( state == Display.STATE_OFF) {
            brightness = PowerManager.BRIGHTNESS_OFF;
        }         ......
            if ((state == Display.STATE_ON
                    && mSkipRampState == RAMP_STATE_SKIP_NONE
                    || state == Display.STATE_DOZE)
                    && !wasOrWillBeInVr) {
                animateScreenBrightness(brightness,
                        slowChange ? mBrightnessRampRateSlow : mBrightnessRampRateFast);
            } else {
                animateScreenBrightness(brightness, 0);
            } }
    private void setProximitySensorEnabled(boolean enable) {
        if (enable) {
            if (!mProximitySensorEnabled) {
                // Register the listener.
                // Proximity sensor state already cleared initially.
                mProximitySensorEnabled = true;
                mSensorManager.registerListener( mProximitySensorListener, mProximitySensor,
                        SensorManager.SENSOR_DELAY_NORMAL, mHandler);
            }
        } else {
            if (mProximitySensorEnabled) {
                 // Unregister the listener.
                // Clear the proximity sensor state for next time.
                mProximitySensorEnabled = false;
                mProximity = PROXIMITY_UNKNOWN;
                mPendingProximity = PROXIMITY_UNKNOWN;
                mHandler.removeMessages(MSG_PROXIMITY_SENSOR_DEBOUNCED);
                mSensorManager.unregisterListener(mProximitySensorListener);
                clearPendingProximityDebounceTime(); // release wake lock (must be last)
            }
        }
    }
    //监听p-Sensor, p-Sensor变化后，收到onSensorChanged，判断是否发生遮挡，     //然后调用updatePowerState()办法更新屏幕状态     private final SensorEventListener mProximitySensorListener = new SensorEventListener() {
        @Override
        public void onSensorChanged(SensorEvent event) {
            if (mProximitySensorEnabled) {
                final long time = SystemClock.uptimeMillis();
                final float distance = event.values[0];
                boolean positive = distance >= 0.0f && distance < mProximityThreshold;
                handleProximitySensorEvent(time, positive);
            }
        }     handleProximitySensorEvent（）     debounceProximitySensor（）     updatePowerState() // 更新屏幕状态 [Z20] ARIMA00015441 GST-PV<7947_Driver_pSensor>- 這題，加下面這段code 應該可以fix     PowerManagerService.java (base\services\core\java\com\android\server\power)     private void goToSleepInternal(long eventTime, int reason, int flags, int uid) {
        synchronized (mLock) {

            if (mProximityPositive && reason == PowerManager.GO_TO_SLEEP_REASON_POWER_BUTTON) {
                Slog.d(TAG, "Proximity positive sleep and do not sleep by power button");
                return;
            }

            if (goToSleepNoUpdateLocked(eventTime, reason, flags, uid)) {
                updatePowerStateLocked();
            }
        }
    } 從code分析，我覺得這個應該是android的原始行為： in call的時候，p-sensor起作用， p-sensor遮住時，只是屏幕滅掉，手機並沒有進sleep模式
這時候，按power key, 手機會進入sleep 模式, p-sensor 會被關閉     private void updatePowerState() {
         ......
        // Apply the proximity sensor.
        if (mProximitySensor != null) {
            if (mPowerRequest.useProximitySensor && state != Display.STATE_OFF) {
                setProximitySensorEnabled(true);
                if (!mScreenOffBecauseOfProximity
                        && mProximity == PROXIMITY_POSITIVE) {
                    mScreenOffBecauseOfProximity = true;
                    sendOnProximityPositiveWithWakelock();
                }
            } else if (mWaitingForNegativeProximity
                    && mScreenOffBecauseOfProximity
                    && mProximity == PROXIMITY_POSITIVE
                    && state != Display.STATE_OFF) {
                setProximitySensorEnabled(true);
            } else {
                setProximitySensorEnabled(false); // 按power key的時候，p-sensor 會被關閉
                mWaitingForNegativeProximity = false;
            } 應為p-sensor已經被關閉了，所以再按一次power key，手機會亮起來通过dumpsys display 可以查看p-sensor的状态 adb shell dumpsys display > d:\display.txt Display Power Controller Thread State:
mPowerRequest=policy=BRIGHT, useProximitySensor=true, screenBrightness=128, screenAutoBrightnessAdjustment=0.0, screenLowPowerBrightnessFactor=0.5, brightnessSetByUser=true, useAutoBrightness=false, blockScreenOn=false, lowPowerMode=false, boostScreenBrightness=false, dozeScreenBrightness=-1, dozeScreenState=UNKNOWN
mWaitingForNegativeProximity=false
mProximitySensor={Sensor name="EPL259x ALS/PS EPL259x", vendor="Eminent", version=2, type=8, maxRange=5.000305, resolution=0.0010070801, power=0.32, minDelay=0}
mProximitySensorEnabled=true
mProximityThreshold=5.0
mProximity=Positive
mPendingProximity=Positive
mPendingProximityDebounceTime=-1 (4802060 ms ago)
mScreenOffBecauseOfProximity=true
mAppliedAutoBrightness=false
mAppliedDimming=false
mAppliedLowPower=false
mPendingScreenOnUnblocker=null
mPendingScreenOff=false
mReportedToPolicy=REPORTED_TO_POLICY_SCREEN_ON
mScreenBrightnessRampAnimator.isAnimating()=false
mColorFadeOnAnimator.isStarted()=false
mColorFadeOffAnimator.isStarted()=false

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