AndroidWIFIPower managment.docx
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AndroidWIFIPowermanagment
AndroidWIFIPowermanagement
1Screenon/off
1.1Figure
1.2Screenon
1.WhenAndroidisinsuspendmode，ifakeyonkeyboardispressed,ThreadInputDeviceReaderwillbecreatedandprocessthekeyevent.SendamessagetoWindowsmanager.
KeyInputQueue.java
ThreadmThread=newThread（"InputDeviceReader"）
abstractbooleanpreprocessEvent（InputDevicedevice,RawInputEventevent）;
2.Windowsmanagerwillhandlethekeyevent,sendamessagetoPowermanagerService.
WindowManagerService.java
BooleanpreprocessEvent（InputDevicedevice,RawInputEventevent）;
userActivity（）
3.PowermanagerServicewillsetpowerstateas:
on,sendbroadcastmessage:
ScreenOnIntent
PowerManagerService.java
PublicvoiduserActivity（longtime,booleannoChangeLights,inteventType,booleanforce）
privatevoidsetPowerState（intnewState,booleannoChangeLights,intreason）
privatevoidsendNotificationLocked（booleanon,intwhy）
mNotificationTask
->mContext.sendOrderedBroadcast（mScreenOnIntent,null,
mScreenOnBroadcastDone,mHandler,0,null,null）;
4.WifiServicewillreceivetheSCREEN_ONintent,willenableRssipolling,thencallupdateWifiState.
if（action.equals（Intent.ACTION_SCREEN_ON））{
Log.d（TAG,"ACTION_SCREEN_ON"）;
mAlarmManager.cancel（mIdleIntent）;
mDeviceIdle=false;
mScreenOff=false;
mWifiStateTracker.enableRssiPolling（true）;
5.updateWifiStatewillsendstartdrivermessage:
MESSAGE_START_WIFItoWifiServiceitself.
if（wifiShouldBeEnabled）{
if（wifiShouldBeStarted）{
sWakeLock.acquire（）;
sendEnableMessage（true,false,mLastEnableUid）;
sWakeLock.acquire（）;
sendStartMessage（strongestLockMode==WifiManager.WIFI_MODE_SCAN_ONLY）;
}
6.HandleMessagewillcallrestartofWifiStateTracker
publicvoidhandleMessage（Messagemsg）{
switch（msg.what）{
caseMESSAGE_START_WIFI:
mWifiStateTracker.setScanOnlyMode（msg.arg1!
=0）;
mWifiStateTracker.restart（）;
sWakeLock.release（）;
break;
7.restartofWifiStateTrackerwillresetinterface,callWifiNative.startDriverCommand
publicsynchronizedbooleanrestart（）{
if（mRunState==RUN_STATE_STOPPED）{
mRunState=RUN_STATE_STARTING;
resetInterface（true）;
returnWifiNative.startDriverCommand（）;
}elseif（mRunState==RUN_STATE_STOPPING）{
mRunState=RUN_STATE_STARTING;
}
returntrue;
}
8.resetInterfacewillclearwifiipaddress,resetConnectionsandstopDHCP.
/**
*ResetstheWi-Fiinterfacebyclearinganystate,resettinganysockets
*usingtheinterface,stoppingDHCP,anddisablingtheinterface.
*/
publicvoidresetInterface（booleanreenable）{
mHaveIpAddress=false;
mObtainingIpAddress=false;
mWifiInfo.setIpAddress（0）;
/*
*ResetconnectiondependsonboththeinterfaceandtheIPassigned,
*soitshouldbedonebeforeanychanceoftheIPbeinglost.
*/
NetworkUtils.resetConnections（mInterfaceName）;
//StopDHCP
if（mDhcpTarget!
=null）{
mDhcpTarget.setCancelCallback（true）;
mDhcpTarget.removeMessages（EVENT_DHCP_START）;
}
if（!
NetworkUtils.stopDhcp（mInterfaceName））{
Log.e（TAG,"CouldnotstopDHCP"）;
}
//[Marvell:
]can'tdisableInterfacehereasthedriverwon'tturnitonautomatically
//NetworkUtils.disableInterface（mInterfaceName）;
//wenolongernettostarttheinterface（driverdoesthisforus）
//anditledtoproblems-removed.
}
/**
*Thesupplicantisreportingthatwearedisconnectedfromthecurrent
*accesspoint.Often,however,adisconnectwillbefollowedveryshortly
*byareconnecttothesameaccesspoint.Therefore,wedelayresetting
*theconnection'sIPstateforabit.
*/
8.WifiNative.startDriverCommandsendstartdrivereventtowpa_suppliant
9.Wpa_supplicantcallwexttohandlestartdriverevent,wpa_supplicant_run–〉eloop_run（void）–〉tmp->handler（tmp->eloop_data,tmp->user_data）;-〉wpa_supplicant_ctrl_iface_receive–〉wpa_supplicant_ctrl_iface_process-〉wpa_supplicant_driver_cmd–〉wpa_drv_driver_cmd-〉wpa_s->driver->driver_cmd（wpa_s->drv_priv,cmd,buf,buf_len）;
10.WextwillcallioctltosendcommandtoWlankerneldriver
11.Wlankerneldriverwillhandlestartdrivercommand（nownotsupportyet）
1.3Screenoff
1.WhenAndroidisinrunningmode，ifthepowerkeyispressed,ThreadInputDeviceReaderwillbecreatedandprocessthekeyevent.SendamessagetoWindowsmanager.
KeyInputQueue.java
ThreadmThread=newThread（"InputDeviceReader"）
abstractbooleanpreprocessEvent（InputDevicedevice,RawInputEventevent）;
2.Windowsmanagerwillhandlethekeyevent,sendamessagetoPowermanagerService.
WindowManagerService.java
BooleanpreprocessEvent（InputDevicedevice,RawInputEventevent）;
userActivity（）
3.PowermanagerServicewillcallsetPowerStatetosetpowerstate,callsendNotificationLockedtonotifypoweronevent.willcallscreenTurnedOffofKeyguardViewMediatortoturnoffscreen,callgoingToSleep（）ofActivityManagerServicetopauseactivity,broadcastintent,Intent（Intent.ACTION_SCREEN_OFF）,sendbroadcastmessage:
ScreenOnIntent
PowerManagerService.java
PublicvoiduserActivity（longtime,booleannoChangeLights,inteventType,booleanforce）
privatevoidsetPowerState（intnewState,booleannoChangeLights,intreason）
privatevoidsendNotificationLocked（booleanon,intwhy）
4.WifiServicewillreceivetheSCREEN_OFFintent,willdisableRssipolling,
SetanalarmtimertosendACTION_DEVICE_IDLE
elseif（action.equals（Intent.ACTION_SCREEN_OFF））{
Log.d（TAG,"ACTION_SCREEN_OFF"）;
mScreenOff=true;
mWifiStateTracker.enableRssiPolling（false）;
/*
*SetatimertoputWi-Fitosleep,butonlyifthescreenisoff
*ANDthe"stayonwhilepluggedin"settingdoesn'tmatchthe
*currentpowerconditions（i.e,notpluggedin,pluggedintoUSB,
*orpluggedintoAC）.
*/
if（!
shouldWifiStayAwake（stayAwakeConditions,mPluggedType））{
WifiInfoinfo=mWifiStateTracker.requestConnectionInfo（）;
if（info.getSupplicantState（）!
=SupplicantState.COMPLETED）{
//weusedtogotosleepimmediately,butthiscausedsomeraceconditions
//wedon'thavetimetotrackdownforthisrelease.Delayinstead,butnot
//aslongaswewouldifconnected（below）
//TODO-fixtheraceconditionsandswitchbacktotheimmediateturn-off
longtriggerTime=System.currentTimeMillis（）+（2*60*1000）;//2min
Log.d（TAG,"settingACTION_DEVICE_IDLEtimerfor120,000ms"）;
mAlarmManager.set（AlarmManager.RTC_WAKEUP,triggerTime,mIdleIntent）;
////donotkeepWifiawakewhenscreenisoffifWifiisnotassociated
//mDeviceIdle=true;
//updateWifiState（）;
}else{
longtriggerTime=System.currentTimeMillis（）+idleMillis;
Log.d（TAG,"settingACTION_DEVICE_IDLEtimerfor"+idleMillis+"ms"）;
mAlarmManager.set（AlarmManager.RTC_WAKEUP,triggerTime,mIdleIntent）;
}
}
5.updateWifiStatewillsendstartdrivermessage:
MESSAGE_STOP_WIFItoWifiServiceitself.
sDriverStopWakeLock.acquire（）;
mWifiHandler.sendEmptyMessage（MESSAGE_STOP_WIFI）;mWifiHandler.sendEmptyMessageDelayed（MESSAGE_RELEASE_WAKELOCK,wakeLockTimeout）;
6.HandleMessagewillcalldisconnectAndStopofWifiStateTracker
publicvoidhandleMessage（Messagemsg）{
caseMESSAGE_STOP_WIFI:
mWifiStateTracker.disconnectAndStop（）;
//don'treleasewakelock
break;
7.disconnectAndStopofWifiStateTrackercallWifiNative.disconnectCommandfirsttodisconnectthewifinetwork.
/**
*Wewanttostopthedriver,butifwe'reconnectedtoanetwork,
*wefirstwanttodisconnect,sothatthesupplicantisalwaysin
*aknownstate（DISCONNECTED）whenthedriverisstopped.
*@return{@codetrue}iftheoperationsucceeds,whichmeansthatthe
*disconnectorstopcommandwasinitiated.
*/
publicsynchronizedbooleandisconnectAndStop（）{
if（mRunState!
=RUN_STATE_STOPPING&&mRunState!
=RUN_STATE_STOPPED）{
//Takedownanyopennetworknotifications
setNotificationVisible（false,0,false,0）;
mRunState=RUN_STATE_STOPPING;
if（mWifiInfo.getSupplicantState（）==SupplicantState.DORMANT）{
returnWifiNative.stopDriverCommand（）;
}else{
returnWifiNative.disconnectCommand（）;
}
}else{
/*
*The"driver-stop"wakelocknormallyisreleasedfromthe
*connectivitymanagerafterthemobiledataconnectionhas
*beenestablished,orafteratimeoutperiod,ifthatnever
*happens.BecauseWifiService.updateWifiState（）cangetcalled
*multipletimes,wecanendupacquiringthewakelockandcalling
*disconnectAndStop（）evenwhenadisconnectorstopoperation
*isalreadyinprogress.Inthatcase,wewanttoignorethe
*disconnectAndStoprequestandreleasethe（ref-counted）wake
*lock,sothateventually,whenthemobiledataconnectionis
*established,therefcountwilldroptozero.
*/
releaseWakeLock（）;
}
returntrue;
}
8.wpa_supplicant_ctrl_iface_processofhandles“DISCONNECT”command,willcallwpa_supplicant_disassociate,thencallwpa_drv_disassociate
voidwpa_supplicant_disassociate（structwpa_supplicant*wpa_s,
intreason_code）
{
u8*addr=NULL;
if（os_memcmp（wpa_s->bssid,"\x00\x00\x00\x00\x00\x00",ETH_ALEN）!
=0）
{
if（wpa_s->use_client_mlme）
ieee80211_sta_disassociate（wpa_s,reason_code）;
else
wpa_drv_disassociate（wpa_s,wpa_s->bssid,reason_code）;
addr=wpa_s->bssid;
}
wpa_clear_keys（wpa_s,addr）;
wpa_supplicant_mark_disassoc（wpa_s）;
wpa_s->current_ssid=NULL;
wpa_sm_set_config（wpa_s->wpa,NULL）;
9.wpa_drv_disassociatewillcallwpa_driver_wext_disassociate
staticintwpa_driver_wext_disassociate（void*priv,constu8*addr,
intreason_code）
{
structwpa_driver_wext_data*drv=priv;
wpa_printf（MSG_DEBUG,"%s",__FUNCTION__）;
returnwpa_driver_wext_mlme（drv,addr,IW_MLME_DISASSOC,
reason_code）;
}
10.wpa_driver_wext_disassociatecallwpa_driver_wext
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