Android 6.0 PowerManagerService 之 Display

继续updatePowerStateLocked函数

// Phase 2: Update display power state.
boolean displayBecameReady = updateDisplayPowerStateLocked(dirtyPhase2);//第一次返回false

systemReady

首先先看systemReady函数中与display相关的，

mDisplayManagerInternal = getLocalService(DisplayManagerInternal.class);

.......

// Initialize display power management.
mDisplayManagerInternal.initPowerManagement(
mDisplayPowerCallbacks, mHandler, sensorManager);

在DisplayManagerService中有一个内部LocalService类，而在PMS的systemReady方法中的mDisplayManagerInternal 也正是这个内部类LocalService，其将mDisplayPowerCallbacks、mHandler、SensorManager传给了DisplayPowerController

DisplayManagerService.java文件中的内部类LocalService

private final class LocalService extends DisplayManagerInternal {
@Override
public void initPowerManagement(final DisplayPowerCallbacks callbacks, Handler handler,
SensorManager sensorManager) {
synchronized (mSyncRoot) {
DisplayBlanker blanker = new DisplayBlanker() {
@Override
public void requestDisplayState(int state, int brightness) {
// The order of operations is important for legacy reasons.
if (state == Display.STATE_OFF) {
requestGlobalDisplayStateInternal(state, brightness);
}

callbacks.onDisplayStateChange(state);

if (state != Display.STATE_OFF) {
requestGlobalDisplayStateInternal(state, brightness);
}
}
};
mDisplayPowerController = new DisplayPowerController(
mContext, callbacks, handler, sensorManager, blanker);
}
}

@Override
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
return mDisplayPowerController.requestPowerState(request,
waitForNegativeProximity);
}

@Override
public boolean isProximitySensorAvailable() {
return mDisplayPowerController.isProximitySensorAvailable();
}

@Override
public DisplayInfo getDisplayInfo(int displayId) {
return getDisplayInfoInternal(displayId, Process.myUid());
}

@Override
public void registerDisplayTransactionListener(DisplayTransactionListener listener) {
if (listener == null) {
throw new IllegalArgumentException("listener must not be null");
}

registerDisplayTransactionListenerInternal(listener);
}

@Override
public void unregisterDisplayTransactionListener(DisplayTransactionListener listener) {
if (listener == null) {
throw new IllegalArgumentException("listener must not be null");
}

unregisterDisplayTransactionListenerInternal(listener);
}

@Override
public void setDisplayInfoOverrideFromWindowManager(int displayId, DisplayInfo info) {
setDisplayInfoOverrideFromWindowManagerInternal(displayId, info);
}

@Override
public void performTraversalInTransactionFromWindowManager() {
performTraversalInTransactionFromWindowManagerInternal();
}

@Override
public void setDisplayProperties(int displayId, boolean hasContent,
float requestedRefreshRate, int requestedMode, boolean inTraversal) {
setDisplayPropertiesInternal(displayId, hasContent, requestedRefreshRate,
requestedMode, inTraversal);
}

@Override
public void setDisplayOffsets(int displayId, int x, int y) {
setDisplayOffsetsInternal(displayId, x, y);
}
}

在上一篇PMS的博客我们，我们分析到updateDisplayPowerStateLocked函数mDisplayManagerInternal.requestPowerState，这里requestPowerState就调用了上面的方法，最后调用了DisplayPowerController里的requestPowerState方法

updateDisplayPowerStateLocked

/**
* Updates the display power state asynchronously.
* When the update is finished, mDisplayReady will be set to true.  The display
* controller posts a message to tell us when the actual display power state
* has been updated so we come back here to double-check and finish up.
*
* This function recalculates the display power state each time.
*
* @return True if the display became ready.
*/
private boolean updateDisplayPowerStateLocked(int dirty) {
final boolean oldDisplayReady = mDisplayReady;
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY | DIRTY_WAKEFULNESS
| DIRTY_ACTUAL_DISPLAY_POWER_STATE_UPDATED | DIRTY_BOOT_COMPLETED
| DIRTY_SETTINGS | DIRTY_SCREEN_BRIGHTNESS_BOOST)) != 0) {
mDisplayPowerRequest.policy = getDesiredScreenPolicyLocked();

// Determine appropriate screen brightness and auto-brightness adjustments.
boolean brightnessSetByUser = true;
int screenBrightness = mScreenBrightnessSettingDefault;
float screenAutoBrightnessAdjustment = 0.0f;
boolean autoBrightness = (mScreenBrightnessModeSetting ==
Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC);
if (isValidBrightness(mScreenBrightnessOverrideFromWindowManager)) {
screenBrightness = mScreenBrightnessOverrideFromWindowManager;
autoBrightness = false;
brightnessSetByUser = false;
} else if (isValidBrightness(mTemporaryScreenBrightnessSettingOverride)) {
screenBrightness = mTemporaryScreenBrightnessSettingOverride;
} else if (isValidBrightness(mScreenBrightnessSetting)) {
screenBrightness = mScreenBrightnessSetting;
}
if (autoBrightness) {
screenBrightness = mScreenBrightnessSettingDefault;
if (isValidAutoBrightnessAdjustment(
mTemporaryScreenAutoBrightnessAdjustmentSettingOverride)) {
screenAutoBrightnessAdjustment =
mTemporaryScreenAutoBrightnessAdjustmentSettingOverride;
} else if (isValidAutoBrightnessAdjustment(
mScreenAutoBrightnessAdjustmentSetting)) {
screenAutoBrightnessAdjustment = mScreenAutoBrightnessAdjustmentSetting;
}
}
screenBrightness = Math.max(Math.min(screenBrightness,
mScreenBrightnessSettingMaximum), mScreenBrightnessSettingMinimum);
screenAutoBrightnessAdjustment = Math.max(Math.min(
screenAutoBrightnessAdjustment, 1.0f), -1.0f);

// Update display power request.
mDisplayPowerRequest.screenBrightness = screenBrightness;
mDisplayPowerRequest.screenAutoBrightnessAdjustment =
screenAutoBrightnessAdjustment;
mDisplayPowerRequest.brightnessSetByUser = brightnessSetByUser;
mDisplayPowerRequest.useAutoBrightness = autoBrightness;
mDisplayPowerRequest.useProximitySensor = shouldUseProximitySensorLocked();
mDisplayPowerRequest.lowPowerMode = mLowPowerModeEnabled;
mDisplayPowerRequest.boostScreenBrightness = mScreenBrightnessBoostInProgress;

if (mDisplayPowerRequest.policy == DisplayPowerRequest.POLICY_DOZE) {
mDisplayPowerRequest.dozeScreenState = mDozeScreenStateOverrideFromDreamManager;
if (mDisplayPowerRequest.dozeScreenState == Display.STATE_DOZE_SUSPEND
&& (mWakeLockSummary & WAKE_LOCK_DRAW) != 0) {
mDisplayPowerRequest.dozeScreenState = Display.STATE_DOZE;
}
mDisplayPowerRequest.dozeScreenBrightness =
mDozeScreenBrightnessOverrideFromDreamManager;
} else {
mDisplayPowerRequest.dozeScreenState = Display.STATE_UNKNOWN;
mDisplayPowerRequest.dozeScreenBrightness = PowerManager.BRIGHTNESS_DEFAULT;
}

mDisplayReady = mDisplayManagerInternal.requestPowerState(mDisplayPowerRequest,
mRequestWaitForNegativeProximity);
mRequestWaitForNegativeProximity = false;

if (DEBUG_SPEW) {
Slog.d(TAG, "updateDisplayPowerStateLocked: mDisplayReady=" + mDisplayReady
+ ", policy=" + mDisplayPowerRequest.policy
+ ", mWakefulness=" + mWakefulness
+ ", mWakeLockSummary=0x" + Integer.toHexString(mWakeLockSummary)
+ ", mUserActivitySummary=0x" + Integer.toHexString(mUserActivitySummary)
+ ", mBootCompleted=" + mBootCompleted
+ ", mScreenBrightnessBoostInProgress="
+ mScreenBrightnessBoostInProgress);
}
}
return mDisplayReady && !oldDisplayReady;
}

DisplayPowerController.java

DisplayPowerController构造函数

/**
* Creates the display power controller.
*/
public DisplayPowerController(Context context,
DisplayPowerCallbacks callbacks, Handler handler,
SensorManager sensorManager, DisplayBlanker blanker) {
mHandler = new DisplayControllerHandler(handler.getLooper());
mCallbacks = callbacks;

mBatteryStats = BatteryStatsService.getService();
mSensorManager = sensorManager;
mWindowManagerPolicy = LocalServices.getService(WindowManagerPolicy.class);
mBlanker = blanker;
mContext = context;

final Resources resources = context.getResources();
final int screenBrightnessSettingMinimum = clampAbsoluteBrightness(resources.getInteger(
com.android.internal.R.integer.config_screenBrightnessSettingMinimum));

mScreenBrightnessDozeConfig = clampAbsoluteBrightness(resources.getInteger(
com.android.internal.R.integer.config_screenBrightnessDoze));

mScreenBrightnessDimConfig = clampAbsoluteBrightness(resources.getInteger(
com.android.internal.R.integer.config_screenBrightnessDim));

mScreenBrightnessDarkConfig = clampAbsoluteBrightness(resources.getInteger(
com.android.internal.R.integer.config_screenBrightnessDark));
if (mScreenBrightnessDarkConfig > mScreenBrightnessDimConfig) {
Slog.w(TAG, "Expected config_screenBrightnessDark ("
+ mScreenBrightnessDarkConfig + ") to be less than or equal to "
+ "config_screenBrightnessDim (" + mScreenBrightnessDimConfig + ").");
}
if (mScreenBrightnessDarkConfig > mScreenBrightnessDimConfig) {
Slog.w(TAG, "Expected config_screenBrightnessDark ("
+ mScreenBrightnessDarkConfig + ") to be less than or equal to "
+ "config_screenBrightnessSettingMinimum ("
+ screenBrightnessSettingMinimum + ").");
}

int screenBrightnessRangeMinimum = Math.min(Math.min(
screenBrightnessSettingMinimum, mScreenBrightnessDimConfig),
mScreenBrightnessDarkConfig);

mScreenBrightnessRangeMaximum = PowerManager.BRIGHTNESS_ON;

mUseSoftwareAutoBrightnessConfig = resources.getBoolean(
com.android.internal.R.bool.config_automatic_brightness_available);

mAllowAutoBrightnessWhileDozingConfig = resources.getBoolean(
com.android.internal.R.bool.config_allowAutoBrightnessWhileDozing);

int lightSensorRate = resources.getInteger(
com.android.internal.R.integer.config_autoBrightnessLightSensorRate);
long brighteningLightDebounce = resources.getInteger(
com.android.internal.R.integer.config_autoBrightnessBrighteningLightDebounce);
long darkeningLightDebounce = resources.getInteger(
com.android.internal.R.integer.config_autoBrightnessDarkeningLightDebounce);
boolean autoBrightnessResetAmbientLuxAfterWarmUp = resources.getBoolean(
com.android.internal.R.bool.config_autoBrightnessResetAmbientLuxAfterWarmUp);

if (mUseSoftwareAutoBrightnessConfig) {
int[] lux = resources.getIntArray(
com.android.internal.R.array.config_autoBrightnessLevels);
int[] screenBrightness = resources.getIntArray(
com.android.internal.R.array.config_autoBrightnessLcdBacklightValues);
int lightSensorWarmUpTimeConfig = resources.getInteger(
com.android.internal.R.integer.config_lightSensorWarmupTime);
final float dozeScaleFactor = resources.getFraction(
com.android.internal.R.fraction.config_screenAutoBrightnessDozeScaleFactor,
1, 1);

Spline screenAutoBrightnessSpline = createAutoBrightnessSpline(lux, screenBrightness);
if (screenAutoBrightnessSpline == null) {
Slog.e(TAG, "Error in config.xml.  config_autoBrightnessLcdBacklightValues "
+ "(size " + screenBrightness.length + ") "
+ "must be monotic and have exactly one more entry than "
+ "config_autoBrightnessLevels (size " + lux.length + ") "
+ "which must be strictly increasing.  "
+ "Auto-brightness will be disabled.");
mUseSoftwareAutoBrightnessConfig = false;
} else {
int bottom = clampAbsoluteBrightness(screenBrightness[0]);
if (mScreenBrightnessDarkConfig > bottom) {
Slog.w(TAG, "config_screenBrightnessDark (" + mScreenBrightnessDarkConfig
+ ") should be less than or equal to the first value of "
+ "config_autoBrightnessLcdBacklightValues ("
+ bottom + ").");
}
if (bottom < screenBrightnessRangeMinimum) {
screenBrightnessRangeMinimum = bottom;
}
mAutomaticBrightnessController = new AutomaticBrightnessController(this,
handler.getLooper(), sensorManager, screenAutoBrightnessSpline,
lightSensorWarmUpTimeConfig, screenBrightnessRangeMinimum,
mScreenBrightnessRangeMaximum, dozeScaleFactor, lightSensorRate,
brighteningLightDebounce, darkeningLightDebounce,
autoBrightnessResetAmbientLuxAfterWarmUp);
}
}

mScreenBrightnessRangeMinimum = screenBrightnessRangeMinimum;

mColorFadeFadesConfig = resources.getBoolean(
com.android.internal.R.bool.config_animateScreenLights);

if (!DEBUG_PRETEND_PROXIMITY_SENSOR_ABSENT) {
mProximitySensor = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);
if (mProximitySensor != null) {
mProximityThreshold = Math.min(mProximitySensor.getMaximumRange(),
TYPICAL_PROXIMITY_THRESHOLD);
}
}

}

requestPowerState

/**
* Requests a new power state.
* The controller makes a copy of the provided object and then
* begins adjusting the power state to match what was requested.
*
* @param request The requested power state.
* @param waitForNegativeProximity If true, issues a request to wait for
* negative proximity before turning the screen back on, assuming the screen
* was turned off by the proximity sensor.
* @return True if display is ready, false if there are important changes that must
* be made asynchronously (such as turning the screen on), in which case the caller
* should grab a wake lock, watch for {@link DisplayPowerCallbacks#onStateChanged()}
* then try the request again later until the state converges.
*/
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
if (DEBUG) {
Slog.d(TAG, "requestPowerState: "
+ request + ", waitForNegativeProximity=" + waitForNegativeProximity);
}

synchronized (mLock) {
boolean changed = false;

if (waitForNegativeProximity
&& !mPendingWaitForNegativeProximityLocked) {
mPendingWaitForNegativeProximityLocked = true;
changed = true;
}

if (mPendingRequestLocked == null) {//第一次进来
mPendingRequestLocked = new DisplayPowerRequest(request);
changed = true;
} else if (!mPendingRequestLocked.equals(request)) {
mPendingRequestLocked.copyFrom(request);
changed = true;
}

if (changed) {
mDisplayReadyLocked = false;//第一次进来mDisplayReadyLocked 为false
}

if (changed && !mPendingRequestChangedLocked) {
mPendingRequestChangedLocked = true;//第一次进来，肯定走进
sendUpdatePowerStateLocked();
}

return mDisplayReadyLocked;//第一次进来返回false
}
}

sendUpdatePowerStateLocked

private void sendUpdatePowerStateLocked() {
if (!mPendingUpdatePowerStateLocked) {
mPendingUpdatePowerStateLocked = true;
Message msg = mHandler.obtainMessage(MSG_UPDATE_POWER_STATE);
msg.setAsynchronous(true);
mHandler.sendMessage(msg);
}
}

发送消息，那么requestPowerState就直接返回mDisplayReadyLocked了。也就是说PMS第一次调用mDisplayManagerInternal.requestPowerState，mDisplayReady 肯定为false

PMS updateDisplayPowerStateLocked 函数中

mDisplayReady = mDisplayManagerInternal.requestPowerState(mDisplayPowerRequest,
mRequestWaitForNegativeProximity);

处理MSG_UPDATE_POWER_STATE消息

@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_UPDATE_POWER_STATE:
updatePowerState();
break;

case MSG_PROXIMITY_SENSOR_DEBOUNCED:
debounceProximitySensor();
break;

case MSG_SCREEN_ON_UNBLOCKED:
if (mPendingScreenOnUnblocker == msg.obj) {
unblockScreenOn();
updatePowerState();
}
break;
}
}

updatePowerState

private void updatePowerState() {
// Update the power state request.
final boolean mustNotify;
boolean mustInitialize = false;
boolean autoBrightnessAdjustmentChanged = false;

synchronized (mLock) {
mPendingUpdatePowerStateLocked = false;
if (mPendingRequestLocked == null) {
return; // wait until first actual power request
}

if (mPowerRequest == null) {//第一次调用必走
mPowerRequest = new DisplayPowerRequest(mPendingRequestLocked);
mWaitingForNegativeProximity = mPendingWaitForNegativeProximityLocked;
mPendingWaitForNegativeProximityLocked = false;
mPendingRequestChangedLocked = false;
mustInitialize = true;
} else if (mPendingRequestChangedLocked) {
autoBrightnessAdjustmentChanged = (mPowerRequest.screenAutoBrightnessAdjustment
!= mPendingRequestLocked.screenAutoBrightnessAdjustment);
mPowerRequest.copyFrom(mPendingRequestLocked);
mWaitingForNegativeProximity |= mPendingWaitForNegativeProximityLocked;
mPendingWaitForNegativeProximityLocked = false;
mPendingRequestChangedLocked = false;
mDisplayReadyLocked = false;
}

mustNotify = !mDisplayReadyLocked;
}

// Initialize things the first time the power state is changed.
if (mustInitialize) {//第一必走
initialize();
}

// Compute the basic display state using the policy.
// We might override this below based on other factors.
int state;
int brightness = PowerManager.BRIGHTNESS_DEFAULT;
boolean performScreenOffTransition = false;
switch (mPowerRequest.policy) {//一会分析
case DisplayPowerRequest.POLICY_OFF:
state = Display.STATE_OFF;
performScreenOffTransition = true;
break;
case DisplayPowerRequest.POLICY_DOZE:
if (mPowerRequest.dozeScreenState != Display.STATE_UNKNOWN) {
state = mPowerRequest.dozeScreenState;
} else {
state = Display.STATE_DOZE;
}
if (!mAllowAutoBrightnessWhileDozingConfig) {
brightness = mPowerRequest.dozeScreenBrightness;
}
break;
case DisplayPowerRequest.POLICY_DIM:
case DisplayPowerRequest.POLICY_BRIGHT:
default:
state = Display.STATE_ON;
break;
}
assert(state != Display.STATE_UNKNOWN);

// 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);
mWaitingForNegativeProximity = false;
}
if (mScreenOffBecauseOfProximity
&& mProximity != PROXIMITY_POSITIVE) {
mScreenOffBecauseOfProximity = false;
sendOnProximityNegativeWithWakelock();
}
} else {
mWaitingForNegativeProximity = false;
}
if (mScreenOffBecauseOfProximity) {
state = Display.STATE_OFF;
}

// Animate the screen state change unless already animating.
// The transition may be deferred, so after this point we will use the
// actual state instead of the desired one.
animateScreenStateChange(state, performScreenOffTransition);
state = mPowerState.getScreenState();

// Use zero brightness when screen is off.
if (state == Display.STATE_OFF) {
brightness = PowerManager.BRIGHTNESS_OFF;
}

// Configure auto-brightness.
boolean autoBrightnessEnabled = false;
if (mAutomaticBrightnessController != null) {
final boolean autoBrightnessEnabledInDoze = mAllowAutoBrightnessWhileDozingConfig
&& (state == Display.STATE_DOZE || state == Display.STATE_DOZE_SUSPEND);
autoBrightnessEnabled = mPowerRequest.useAutoBrightness
&& (state == Display.STATE_ON || autoBrightnessEnabledInDoze)
&& brightness < 0;
final boolean userInitiatedChange = autoBrightnessAdjustmentChanged
&& mPowerRequest.brightnessSetByUser;
mAutomaticBrightnessController.configure(autoBrightnessEnabled,
mPowerRequest.screenAutoBrightnessAdjustment, state != Display.STATE_ON,
userInitiatedChange);
}

// Apply brightness boost.
// We do this here after configuring auto-brightness so that we don't
// disable the light sensor during this temporary state.  That way when
// boost ends we will be able to resume normal auto-brightness behavior
// without any delay.
if (mPowerRequest.boostScreenBrightness
&& brightness != PowerManager.BRIGHTNESS_OFF) {
brightness = PowerManager.BRIGHTNESS_ON;
}

// Apply auto-brightness.
boolean slowChange = false;
if (brightness < 0) {
if (autoBrightnessEnabled) {
brightness = mAutomaticBrightnessController.getAutomaticScreenBrightness();
}
if (brightness >= 0) {
// Use current auto-brightness value and slowly adjust to changes.
brightness = clampScreenBrightness(brightness);
if (mAppliedAutoBrightness && !autoBrightnessAdjustmentChanged) {
slowChange = true; // slowly adapt to auto-brightness
}
mAppliedAutoBrightness = true;
} else {
mAppliedAutoBrightness = false;
}
} else {
mAppliedAutoBrightness = false;
}

// Use default brightness when dozing unless overridden.
if (brightness < 0 && (state == Display.STATE_DOZE
|| state == Display.STATE_DOZE_SUSPEND)) {
brightness = mScreenBrightnessDozeConfig;
}

// Apply manual brightness.
// Use the current brightness setting from the request, which is expected
// provide a nominal default value for the case where auto-brightness
// is not ready yet.
if (brightness < 0) {
brightness = clampScreenBrightness(mPowerRequest.screenBrightness);
}

// Apply dimming by at least some minimum amount when user activity
// timeout is about to expire.
if (mPowerRequest.policy == DisplayPowerRequest.POLICY_DIM) {
if (brightness > mScreenBrightnessRangeMinimum) {
brightness = Math.max(Math.min(brightness - SCREEN_DIM_MINIMUM_REDUCTION,
mScreenBrightnessDimConfig), mScreenBrightnessRangeMinimum);
}
if (!mAppliedDimming) {
slowChange = false;
}
mAppliedDimming = true;
}

// If low power mode is enabled, cut the brightness level by half
// as long as it is above the minimum threshold.
if (mPowerRequest.lowPowerMode) {
if (brightness > mScreenBrightnessRangeMinimum) {
brightness = Math.max(brightness / 2, mScreenBrightnessRangeMinimum);
}
if (!mAppliedLowPower) {
slowChange = false;
}
mAppliedLowPower = true;
}

// Animate the screen brightness when the screen is on or dozing.
// Skip the animation when the screen is off or suspended.
if (!mPendingScreenOff) {//这个时候没有灭屏动画
if (state == Display.STATE_ON || state == Display.STATE_DOZE) {
animateScreenBrightness(brightness,// 这个函数也是在DisplayPowerState设置亮度，待会详细分析
slowChange ? BRIGHTNESS_RAMP_RATE_SLOW : BRIGHTNESS_RAMP_RATE_FAST);
} else {
animateScreenBrightness(brightness, 0);
}
}

// Determine whether the display is ready for use in the newly requested state.
// Note that we do not wait for the brightness ramp animation to complete before
// reporting the display is ready because we only need to ensure the screen is in the
// right power state even as it continues to converge on the desired brightness.
final boolean ready = mPendingScreenOnUnblocker == null
&& !mColorFadeOnAnimator.isStarted()
&& !mColorFadeOffAnimator.isStarted()
&& mPowerState.waitUntilClean(mCleanListener);
final boolean finished = ready
&& !mScreenBrightnessRampAnimator.isAnimating();

// Notify policy about screen turned on.
if (ready && state != Display.STATE_OFF
&& mReportedScreenStateToPolicy == REPORTED_TO_POLICY_SCREEN_TURNING_ON) {
mReportedScreenStateToPolicy = REPORTED_TO_POLICY_SCREEN_ON;
mWindowManagerPolicy.screenTurnedOn();
}

// Grab a wake lock if we have unfinished business.
if (!finished && !mUnfinishedBusiness) {
if (DEBUG) {
Slog.d(TAG, "Unfinished business...");
}
mCallbacks.acquireSuspendBlocker();
mUnfinishedBusiness = true;
}

// Notify the power manager when ready.
if (ready && mustNotify) {
// Send state change.
synchronized (mLock) {
if (!mPendingRequestChangedLocked) {
mDisplayReadyLocked = true;

if (DEBUG) {
Slog.d(TAG, "Display ready!");
}
}
}
sendOnStateChangedWithWakelock();//完成工作后通知PMS
}

// Release the wake lock when we have no unfinished business.
if (finished && mUnfinishedBusiness) {
if (DEBUG) {
Slog.d(TAG, "Finished business...");
}
mUnfinishedBusiness = false;
mCallbacks.releaseSuspendBlocker();
}
}

先看这个mCallbacks，是PMS传进来的回调 systemReady

// Initialize display power management.
mDisplayManagerInternal.initPowerManagement(
mDisplayPowerCallbacks, mHandler, sensorManager);

initialize

private void initialize() {
// Initialize the power state object for the default display.
// In the future, we might manage multiple displays independently.
mPowerState = new DisplayPowerState(mBlanker,
new ColorFade(Display.DEFAULT_DISPLAY));

mColorFadeOnAnimator = ObjectAnimator.ofFloat(
mPowerState, DisplayPowerState.COLOR_FADE_LEVEL, 0.0f, 1.0f);
mColorFadeOnAnimator.setDuration(COLOR_FADE_ON_ANIMATION_DURATION_MILLIS);
mColorFadeOnAnimator.addListener(mAnimatorListener);

mColorFadeOffAnimator = ObjectAnimator.ofFloat(
mPowerState, DisplayPowerState.COLOR_FADE_LEVEL, 1.0f, 0.0f);
mColorFadeOffAnimator.setDuration(COLOR_FADE_OFF_ANIMATION_DURATION_MILLIS);
mColorFadeOffAnimator.addListener(mAnimatorListener);

mScreenBrightnessRampAnimator = new RampAnimator<DisplayPowerState>(
mPowerState, DisplayPowerState.SCREEN_BRIGHTNESS);
mScreenBrightnessRampAnimator.setListener(mRampAnimatorListener);

// Initialize screen state for battery stats.
try {
mBatteryStats.noteScreenState(mPowerState.getScreenState());
mBatteryStats.noteScreenBrightness(mPowerState.getScreenBrightness());
} catch (RemoteException ex) {
// same process
}
}

继续分析，根据传进来的mPowerRequest.policy不同，走不同的case

// Compute the basic display state using the policy.
// We might override this below based on other factors.
int state;
int brightness = PowerManager.BRIGHTNESS_DEFAULT;
boolean performScreenOffTransition = false;
switch (mPowerRequest.policy) {
case DisplayPowerRequest.POLICY_OFF:
state = Display.STATE_OFF;
performScreenOffTransition = true;
break;
case DisplayPowerRequest.POLICY_DOZE:
if (mPowerRequest.dozeScreenState != Display.STATE_UNKNOWN) {
state = mPowerRequest.dozeScreenState;
} else {
state = Display.STATE_DOZE;
}
if (!mAllowAutoBrightnessWhileDozingConfig) {
brightness = mPowerRequest.dozeScreenBrightness;
}
break;
case DisplayPowerRequest.POLICY_DIM:
case DisplayPowerRequest.POLICY_BRIGHT:
default:
state = Display.STATE_ON;
break;
}

看看PMS这个mPowerRequest.policy值，在updateDisplayPowerStateLocked函数中

private boolean updateDisplayPowerStateLocked(int dirty) {
final boolean oldDisplayReady = mDisplayReady;
if ((dirty & (DIRTY_WAKE_LOCKS | DIRTY_USER_ACTIVITY | DIRTY_WAKEFULNESS
| DIRTY_ACTUAL_DISPLAY_POWER_STATE_UPDATED | DIRTY_BOOT_COMPLETED
| DIRTY_SETTINGS | DIRTY_SCREEN_BRIGHTNESS_BOOST)) != 0) {
mDisplayPowerRequest.policy = getDesiredScreenPolicyLocked();

getDesiredScreenPolicyLocked

private int getDesiredScreenPolicyLocked() {
if (mWakefulness == WAKEFULNESS_ASLEEP) {
return DisplayPowerRequest.POLICY_OFF;
}

if (mWakefulness == WAKEFULNESS_DOZING) {
if ((mWakeLockSummary & WAKE_LOCK_DOZE) != 0) {
return DisplayPowerRequest.POLICY_DOZE;
}
if (mDozeAfterScreenOffConfig) {
return DisplayPowerRequest.POLICY_OFF;
}
// Fall through and preserve the current screen policy if not configured to
// doze after screen off.  This causes the screen off transition to be skipped.
}

if ((mWakeLockSummary & WAKE_LOCK_SCREEN_BRIGHT) != 0
|| (mUserActivitySummary & USER_ACTIVITY_SCREEN_BRIGHT) != 0
|| !mBootCompleted
|| mScreenBrightnessBoostInProgress) {
return DisplayPowerRequest.POLICY_BRIGHT;
}

return DisplayPowerRequest.POLICY_DIM;
}

animateScreenStateChange

继续分析animateScreenStateChange

private void animateScreenStateChange(int target, boolean performScreenOffTransition) {
// If there is already an animation in progress, don't interfere with it.
if (mColorFadeOnAnimator.isStarted()
|| mColorFadeOffAnimator.isStarted()) {
return;
}

// If we were in the process of turning off the screen but didn't quite
// finish.  Then finish up now to prevent a jarring transition back
// to screen on if we skipped blocking screen on as usual.
if (mPendingScreenOff && target != Display.STATE_OFF) {//灭屏动画
setScreenState(Display.STATE_OFF);
mPendingScreenOff = false;
mPowerState.dismissColorFadeResources();
}

if (target == Display.STATE_ON) {
// Want screen on.  The contents of the screen may not yet
// be visible if the color fade has not been dismissed because
// its last frame of animation is solid black.
if (!setScreenState(Display.STATE_ON)) {
return; // screen on blocked
}
if (USE_COLOR_FADE_ON_ANIMATION && mPowerRequest.isBrightOrDim()) {
// Perform screen on animation.
if (mPowerState.getColorFadeLevel() == 1.0f) {
mPowerState.dismissColorFade();
} else if (mPowerState.prepareColorFade(mContext,
mColorFadeFadesConfig ?
ColorFade.MODE_FADE :
ColorFade.MODE_WARM_UP)) {
mColorFadeOnAnimator.start();
} else {
mColorFadeOnAnimator.end();
}
} else {
// Skip screen on animation.
mPowerState.setColorFadeLevel(1.0f);
mPowerState.dismissColorFade();
}
} else if (target == Display.STATE_DOZE) {
// Want screen dozing.
// Wait for brightness animation to complete beforehand when entering doze
// from screen on to prevent a perceptible jump because brightness may operate
// differently when the display is configured for dozing.
if (mScreenBrightnessRampAnimator.isAnimating()
&& mPowerState.getScreenState() == Display.STATE_ON) {
return;
}

// Set screen state.
if (!setScreenState(Display.STATE_DOZE)) {
return; // screen on blocked
}

// Dismiss the black surface without fanfare.
mPowerState.setColorFadeLevel(1.0f);
mPowerState.dismissColorFade();
} else if (target == Display.STATE_DOZE_SUSPEND) {
// Want screen dozing and suspended.
// Wait for brightness animation to complete beforehand unless already
// suspended because we may not be able to change it after suspension.
if (mScreenBrightnessRampAnimator.isAnimating()
&& mPowerState.getScreenState() != Display.STATE_DOZE_SUSPEND) {
return;
}

// If not already suspending, temporarily set the state to doze until the
// screen on is unblocked, then suspend.
if (mPowerState.getScreenState() != Display.STATE_DOZE_SUSPEND) {
if (!setScreenState(Display.STATE_DOZE)) {
return; // screen on blocked
}
setScreenState(Display.STATE_DOZE_SUSPEND); // already on so can't block
}

// Dismiss the black surface without fanfare.
mPowerState.setColorFadeLevel(1.0f);
mPowerState.dismissColorFade();
} else {
// Want screen off.
mPendingScreenOff = true;
if (mPowerState.getColorFadeLevel() == 0.0f) {
// Turn the screen off.
// A black surface is already hiding the contents of the screen.
setScreenState(Display.STATE_OFF);
mPendingScreenOff = false;
mPowerState.dismissColorFadeResources();
} else if (performScreenOffTransition
&& mPowerState.prepareColorFade(mContext,
mColorFadeFadesConfig ?
ColorFade.MODE_FADE : ColorFade.MODE_COOL_DOWN)
&& mPowerState.getScreenState() != Display.STATE_OFF) {
// Perform the screen off animation.
mColorFadeOffAnimator.start();
} else {
// Skip the screen off animation and add a black surface to hide the
// contents of the screen.
mColorFadeOffAnimator.end();
}
}
}

setScreenState
再看看 setScreenState

private boolean setScreenState(int state) {
if (mPowerState.getScreenState() != state) {
final boolean wasOn = (mPowerState.getScreenState() != Display.STATE_OFF);
mPowerState.setScreenState(state);//调用DisplayPowerState的setScreenState函数，后面再分析

// Tell battery stats about the transition.
try {
mBatteryStats.noteScreenState(state);//电池记录
} catch (RemoteException ex) {
// same process
}
}

// Tell the window manager policy when the screen is turned off or on unless it's due
// to the proximity sensor.  We temporarily block turning the screen on until the
// window manager is ready by leaving a black surface covering the screen.
// This surface is essentially the final state of the color fade animation and
// it is only removed once the window manager tells us that the activity has
// finished drawing underneath.
final boolean isOff = (state == Display.STATE_OFF);
if (isOff && mReportedScreenStateToPolicy != REPORTED_TO_POLICY_SCREEN_OFF
&& !mScreenOffBecauseOfProximity) {
mReportedScreenStateToPolicy = REPORTED_TO_POLICY_SCREEN_OFF;
unblockScreenOn();
mWindowManagerPolicy.screenTurnedOff();//通知phonewindowManager
} else if (!isOff && mReportedScreenStateToPolicy == REPORTED_TO_POLICY_SCREEN_OFF) {
mReportedScreenStateToPolicy = REPORTED_TO_POLICY_SCREEN_TURNING_ON;
if (mPowerState.getColorFadeLevel() == 0.0f) {
blockScreenOn();
} else {
unblockScreenOn();
}
mWindowManagerPolicy.screenTurningOn(mPendingScreenOnUnblocker);
}

// Return true if the screen isn't blocked.
return mPendingScreenOnUnblocker == null;
}

再看看sendOnStateChangedWithWakelock函数

sendOnStateChangedWithWakelock

private void sendOnStateChangedWithWakelock() {
mCallbacks.acquireSuspendBlocker();
mHandler.post(mOnStateChangedRunnable);
}

private final Runnable mOnStateChangedRunnable = new Runnable() {
@Override
public void run() {
mCallbacks.onStateChanged();
mCallbacks.releaseSuspendBlocker();
}
};

而PMS里的mDisplayPowerCallbacks 的onStateChanged如下

           // Initialize display power management.
mDisplayManagerInternal.initPowerManagement(
mDisplayPowerCallbacks, mHandler, sensorManager);

private final DisplayManagerInternal.DisplayPowerCallbacks mDisplayPowerCallbacks =
new DisplayManagerInternal.DisplayPowerCallbacks() {
private int mDisplayState = Display.STATE_UNKNOWN;

@Override
public void onStateChanged() {
synchronized (mLock) {
mDirty |= DIRTY_ACTUAL_DISPLAY_POWER_STATE_UPDATED;
updatePowerStateLocked();//更新状态
}
}

会重新调用到PMS的updateDisplayPowerStateLocked函数，再调用下面。

mDisplayReady = mDisplayManagerInternal.requestPowerState(mDisplayPowerRequest,
mRequestWaitForNegativeProximity);
mRequestWaitForNegativeProximity = false;

由于changed没有变化，最后返回true

然后 DisplayManagerService.java 文件的localService

@Override
public boolean requestPowerState(DisplayPowerRequest request,
boolean waitForNegativeProximity) {
return mDisplayPowerController.requestPowerState(request,
waitForNegativeProximity);
}

继续分析updatePowerStateLocked

// Phase 2: Update display power state.
boolean displayBecameReady = updateDisplayPowerStateLocked(dirtyPhase2);

// Phase 3: Update dream state (depends on display ready signal).
updateDreamLocked(dirtyPhase2, displayBecameReady);

// Phase 4: Send notifications, if needed.
finishWakefulnessChangeIfNeededLocked();

// Phase 5: Update suspend blocker.
// Because we might release the last suspend blocker here, we need to make sure
// we finished everything else first!
updateSuspendBlockerLocked();
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}

先看updateDreamLocked函数，mDisplayReady为false，所以跳出

/**
* Determines whether to post a message to the sandman to update the dream state.
*/
private void updateDreamLocked(int dirty, boolean displayBecameReady) {
if ((dirty & (DIRTY_WAKEFULNESS
| DIRTY_USER_ACTIVITY
| DIRTY_WAKE_LOCKS
| DIRTY_BOOT_COMPLETED
| DIRTY_SETTINGS
| DIRTY_IS_POWERED
| DIRTY_STAY_ON
| DIRTY_PROXIMITY_POSITIVE
| DIRTY_BATTERY_STATE)) != 0 || displayBecameReady) {
if (mDisplayReady) {
scheduleSandmanLocked();
}
}
}

再看 updateSuspendBlockerLocked函数

/**
* Updates the suspend blocker that keeps the CPU alive.
*
* This function must have no other side-effects.
*/
private void updateSuspendBlockerLocked() {
final boolean needWakeLockSuspendBlocker = ((mWakeLockSummary & WAKE_LOCK_CPU) != 0);//看cpu是否要持锁
final boolean needDisplaySuspendBlocker = needDisplaySuspendBlockerLocked();//现在Display没好，需要持Display的锁
final boolean autoSuspend = !needDisplaySuspendBlocker;
final boolean interactive = mDisplayPowerRequest.isBrightOrDim();

// Disable auto-suspend if needed.
// FIXME We should consider just leaving auto-suspend enabled forever since
// we already hold the necessary wakelocks.
if (!autoSuspend && mDecoupleHalAutoSuspendModeFromDisplayConfig) {
setHalAutoSuspendModeLocked(false);
}

// First acquire suspend blockers if needed.
if (needWakeLockSuspendBlocker && !mHoldingWakeLockSuspendBlocker) {
mWakeLockSuspendBlocker.acquire();
mHoldingWakeLockSuspendBlocker = true;
}
if (needDisplaySuspendBlocker && !mHoldingDisplaySuspendBlocker) {
mDisplaySuspendBlocker.acquire();
mHoldingDisplaySuspendBlocker = true;
}

// Inform the power HAL about interactive mode.
// Although we could set interactive strictly based on the wakefulness
// as reported by isInteractive(), it is actually more desirable to track
// the display policy state instead so that the interactive state observed
// by the HAL more accurately tracks transitions between AWAKE and DOZING.
// Refer to getDesiredScreenPolicyLocked() for details.
if (mDecoupleHalInteractiveModeFromDisplayConfig) {
// When becoming non-interactive, we want to defer sending this signal
// until the display is actually ready so that all transitions have
// completed.  This is probably a good sign that things have gotten
// too tangled over here...
if (interactive || mDisplayReady) {
setHalInteractiveModeLocked(interactive);//修改cpu频率等
}
}

// Then release suspend blockers if needed.
if (!needWakeLockSuspendBlocker && mHoldingWakeLockSuspendBlocker) {
mWakeLockSuspendBlocker.release();
mHoldingWakeLockSuspendBlocker = false;
}
if (!needDisplaySuspendBlocker && mHoldingDisplaySuspendBlocker) {
mDisplaySuspendBlocker.release();
mHoldingDisplaySuspendBlocker = false;
}

// Enable auto-suspend if needed.
if (autoSuspend && mDecoupleHalAutoSuspendModeFromDisplayConfig) {
setHalAutoSuspendModeLocked(true);//设置true，让系统可以自动睡眠
}
}

needDisplaySuspendBlockerLocked函数mDisplayReady为false，直接返回true

/**
* Return true if we must keep a suspend blocker active on behalf of the display.
* We do so if the screen is on or is in transition between states.
*/
private boolean needDisplaySuspendBlockerLocked() {
if (!mDisplayReady) {
return true;
}
if (mDisplayPowerRequest.isBrightOrDim()) {
// If we asked for the screen to be on but it is off due to the proximity
// sensor then we may suspend but only if the configuration allows it.
// On some hardware it may not be safe to suspend because the proximity
// sensor may not be correctly configured as a wake-up source.
if (!mDisplayPowerRequest.useProximitySensor || !mProximityPositive
|| !mSuspendWhenScreenOffDueToProximityConfig) {
return true;
}
}
if (mScreenBrightnessBoostInProgress) {
return true;
}
// Let the system suspend if the screen is off or dozing.
return false;
}

这样PMS刚调mDisplayManagerInternal.requestPowerState的时候，返回mDisplayReady为false，最后也就会持Display的锁，

直到Display准备好，回调函数直接又调用updatePowerStateLocked函数，再调用updateDisplayPowerStateLocked函数，返回mDisplayReady为true。

那我们继续分析updatePowerStateLocked函数

// Phase 3: Update dream state (depends on display ready signal).
updateDreamLocked(dirtyPhase2, displayBecameReady);

// Phase 4: Send notifications, if needed.
finishWakefulnessChangeIfNeededLocked();

// Phase 5: Update suspend blocker.
// Because we might release the last suspend blocker here, we need to make sure
// we finished everything else first!
updateSuspendBlockerLocked();
} finally {
Trace.traceEnd(Trace.TRACE_TAG_POWER);
}

updateDreamLocked函数发送消息，消息最后处理的函数是handleSandman，goToSleepNoUpdateLocked和napNoUpdateLocked函数才会把mSandmanSummoned = true

private void scheduleSandmanLocked() {
if (!mSandmanScheduled) {
mSandmanScheduled = true;
Message msg = mHandler.obtainMessage(MSG_SANDMAN);
msg.setAsynchronous(true);
mHandler.sendMessage(msg);
}
}

/**
* Called when the device enters or exits a dreaming or dozing state.
*
* We do this asynchronously because we must call out of the power manager to start
* the dream and we don't want to hold our lock while doing so.  There is a risk that
* the device will wake or go to sleep in the meantime so we have to handle that case.
*/
private void handleSandman() { // runs on handler thread
// Handle preconditions.
final boolean startDreaming;
final int wakefulness;
synchronized (mLock) {
mSandmanScheduled = false;
wakefulness = mWakefulness;
if (mSandmanSummoned && mDisplayReady) {//mSandmanSummoned为donzing状态和dreaming状态的时候才为true
startDreaming = canDreamLocked() || canDozeLocked();//canDozeLocked函数只要wakefulness == WAKEFULNESS_DOZING就true
mSandmanSummoned = false;
} else {
startDreaming = false;
}
}

// Start dreaming if needed.
// We only control the dream on the handler thread, so we don't need to worry about
// concurrent attempts to start or stop the dream.
final boolean isDreaming;
if (mDreamManager != null) {
// Restart the dream whenever the sandman is summoned.
if (startDreaming) {
mDreamManager.stopDream(false /*immediate*/);
mDreamManager.startDream(wakefulness == WAKEFULNESS_DOZING);
}
isDreaming = mDreamManager.isDreaming();
} else {
isDreaming = false;
}

// Update dream state.
synchronized (mLock) {
// Remember the initial battery level when the dream started.
if (startDreaming && isDreaming) {
mBatteryLevelWhenDreamStarted = mBatteryLevel;
if (wakefulness == WAKEFULNESS_DOZING) {
Slog.i(TAG, "Dozing...");
} else {
Slog.i(TAG, "Dreaming...");
}
}

// If preconditions changed, wait for the next iteration to determine
// whether the dream should continue (or be restarted).
if (mSandmanSummoned || mWakefulness != wakefulness) {
return; // wait for next cycle
}

// Determine whether the dream should continue.
if (wakefulness == WAKEFULNESS_DREAMING) {
if (isDreaming && canDreamLocked()) {
if (mDreamsBatteryLevelDrainCutoffConfig >= 0
&& mBatteryLevel < mBatteryLevelWhenDreamStarted
- mDreamsBatteryLevelDrainCutoffConfig
&& !isBeingKeptAwakeLocked()) {
// If the user activity timeout expired and the battery appears
// to be draining faster than it is charging then stop dreaming
// and go to sleep.
Slog.i(TAG, "Stopping dream because the battery appears to "
+ "be draining faster than it is charging.  "
+ "Battery level when dream started: "
+ mBatteryLevelWhenDreamStarted + "%.  "
+ "Battery level now: " + mBatteryLevel + "%.");
} else {
return; // continue dreaming
}
}

// Dream has ended or will be stopped.  Update the power state.
if (isItBedTimeYetLocked()) {//dream 停止，开始sleep
goToSleepNoUpdateLocked(SystemClock.uptimeMillis(),
PowerManager.GO_TO_SLEEP_REASON_TIMEOUT, 0, Process.SYSTEM_UID);
updatePowerStateLocked();
} else {
wakeUpNoUpdateLocked(SystemClock.uptimeMillis(), "android.server.power:DREAM",
Process.SYSTEM_UID, mContext.getOpPackageName(), Process.SYSTEM_UID);
updatePowerStateLocked();
}
} else if (wakefulness == WAKEFULNESS_DOZING) {//WAKEFULNESS_DOZING和WAKEFULNESS_DREAMING都可以做梦
if (isDreaming) {
return; // continue dozing
}

// Doze has ended or will be stopped.  Update the power state.
reallyGoToSleepNoUpdateLocked(SystemClock.uptimeMillis(), Process.SYSTEM_UID);//直接sleep
updatePowerStateLocked();
}
}

// Stop dream.
if (isDreaming) {
mDreamManager.stopDream(false /*immediate*/);
}
}

继续分析PMS中的updatePowerStateLocked函数

// Phase 4: Send notifications, if needed.
finishWakefulnessChangeIfNeededLocked();

// Phase 5: Update suspend blocker.
// Because we might release the last suspend blocker here, we need to make sure
// we finished everything else first!
updateSuspendBlockerLocked();
}

Display完成后，屏幕在灭屏之前通知PhoneWindowManager，电池统计等。updateSuspendBlockerLocked函数持有一个锁，和调JNI设置cpu频率，还有一个autoSuspend是自动让系统睡眠，如果开启就设true。

亮度调节的时序图