Enhancement 4G mode流程

1. About Enhancement 4G mode

use LTE services to improve voice and other communications

2. Set on/off

Settings->more->cellular networks->VoLTE

3. Save

the setting result save to SystemProperties:PROPERTY_VOLTE_ENALBE

4. Setting on/off flow:

packages/services/Telephony/src/com/android/phone/MobileNetworkSettings.java

public boolean onPreferenceChange(Preference preference, Object objValue) {
	...
	mImsMgr.setEnhanced4gLteModeSetting(mButton4glte.isChecked());
	...
}

frameworks/opt/net/ims/src/java/com/android/ims/ImsManager.java

public void setEnhanced4gLteModeSetting(boolean enabled) {
	...
	SubscriptionManager.setSubscriptionProperty(subId,
                        SubscriptionManager.ENHANCED_4G_MODE_ENABLED,
                        booleanToPropertyString(enabled));
    ...
    setAdvanced4GMode(enabled);
    ...
}

frameworks/base/telephony/java/android/telephony/SubscriptionManager.java

public static void setSubscriptionProperty(int subId, String propKey, String propValue) {
    try {
        ISub iSub = ISub.Stub.asInterface(ServiceManager.getService("isub"));
        if (iSub != null) {
            iSub.setSubscriptionProperty(subId, propKey, propValue);
        }
    } catch (RemoteException ex) {
        // ignore it
    }
}

//frameworks/opt/telephony/src/java/com/android/internal/telephony/SubscriptionController.java
public int setSubscriptionProperty(int subId, String propKey, String propValue){...}

frameworks/opt/net/ims/src/java/com/android/ims/ImsManager.java

private void setAdvanced4GMode(boolean turnOn) throws ImsException {
    checkAndThrowExceptionIfServiceUnavailable();
    // if turnOn: first set feature values then call turnOnIms()
    // if turnOff: only set feature values if IMS turn off is not allowed. If turn off is
    // allowed, first call turnOffIms() then set feature values
    if (turnOn) {
        setLteFeatureValues(turnOn);
        log("setAdvanced4GMode: turnOnIms");
        turnOnIms();
    } else {
        if (isImsTurnOffAllowed()) {
            log("setAdvanced4GMode: turnOffIms");
            turnOffIms();
        }
        setLteFeatureValues(turnOn);
    }
}

private void setLteFeatureValues(boolean turnOn) {
    log("setLteFeatureValues: " + turnOn);
    CapabilityChangeRequest request = new CapabilityChangeRequest();
    if (turnOn) {
        request.addCapabilitiesToEnableForTech(
                MmTelFeature.MmTelCapabilities.CAPABILITY_TYPE_VOICE,
                ImsRegistrationImplBase.REGISTRATION_TECH_LTE);
    } else {
        request.addCapabilitiesToDisableForTech(
                MmTelFeature.MmTelCapabilities.CAPABILITY_TYPE_VOICE,
                ImsRegistrationImplBase.REGISTRATION_TECH_LTE);
    }

    if (isVtEnabledByPlatform()) {
        boolean ignoreDataEnabledChanged = getBooleanCarrierConfig(
                CarrierConfigManager.KEY_IGNORE_DATA_ENABLED_CHANGED_FOR_VIDEO_CALLS);
        boolean enableViLte = turnOn && isVtEnabledByUser() &&
                (ignoreDataEnabledChanged || isDataEnabled());
        if (enableViLte) {
            request.addCapabilitiesToEnableForTech(
                    MmTelFeature.MmTelCapabilities.CAPABILITY_TYPE_VIDEO,
                    ImsRegistrationImplBase.REGISTRATION_TECH_LTE);
        } else {
            request.addCapabilitiesToDisableForTech(
                    MmTelFeature.MmTelCapabilities.CAPABILITY_TYPE_VIDEO,
                    ImsRegistrationImplBase.REGISTRATION_TECH_LTE);
        }
    }
    try {
        mMmTelFeatureConnection.changeEnabledCapabilities(request, null);
    } catch (RemoteException e) {
        Log.e(TAG, "setLteFeatureValues: Exception: " + e.getMessage());
    }
}

//frameworks/opt/net/ims/src/java/com/android/ims/MmTelFeatureConnection.java
public void changeEnabledCapabilities(CapabilityChangeRequest request,
        IImsCapabilityCallback callback) throws RemoteException {
    synchronized (mLock) {
        checkServiceIsReady();
        getServiceInterface(mBinder).changeCapabilitiesConfiguration(request, callback);
    }
}

//frameworks/base/telephony/java/android/telephony/ims/feature/MmTelFeature.java
public void changeCapabilitiesConfiguration(CapabilityChangeRequest request,
                IImsCapabilityCallback c) {
   synchronized (mLock) {
       MmTelFeature.this.requestChangeEnabledCapabilities(request, c);
   }
}

//frameworks/base/telephony/java/android/telephony/ims/feature/ImsFeature.java
public final void requestChangeEnabledCapabilities(CapabilityChangeRequest request,
            IImsCapabilityCallback c) {
    if (request == null) {
        throw new IllegalArgumentException(
                "ImsFeature#requestChangeEnabledCapabilities called with invalid params.");
    }
    changeEnabledCapabilities(request, new CapabilityCallbackProxy(c));
}

public abstract void changeEnabledCapabilities(CapabilityChangeRequest request,
            CapabilityCallbackProxy c);
//該方法爲抽象方法，需要功能部件自己去實現，這部分在MTK&高通平臺有不同實現

5. 流程時序圖