一. 螢幕的喚醒
首先inputread在讀取到有keyboard事件上報後，會調用到keydispatch的notifykey，去詢問wm是否會對這次按鍵特殊處理,如果WM不處理，則此處會點亮或者熄滅螢幕。
inputReader.cpp KeyboardInputMapper::processKey
getDispatcher()->notifyKey
inputDispacher.cpp InputDispatcher::notifyKey
mPolicy->interceptKeyBeforeQueueing
com_android_server_inputManager.cpp NativeInputManager::interceptKeyBeforeQueueing
env->CallIntMethod(mCallbacksObj,
gCallbacksClassInfo.interceptKeyBeforeQueueing,
when, action, flags, keyCode, scanCode, policyFlags,
isScreenOn);
//此處gCallbacksClassInfo中的各種方法就是InputManager的對應的方法，在JNI初始化的時候就注冊了，詳情請參看
register_android_server_InputManager函數，通過jniRegisterNativeMethods将
inputmanager的各種callback注冊到gCallbacksClassInfo中。
傳回的wmaction就是後面WM對此次按鍵事件的policy，通過此傳回值，此處會決定下一步的動作。
InputManager.java interceptKeyBeforeQueueing
mWindowManagerService.mInputMonitor.interceptKeyBeforeQueueing
WindowmanagerService.java InputMonitor::interceptKeyBeforeQueueing
mPolicy.interceptKeyBeforeQueueing
PhonewindowManager.java interceptKeyBeforeQueueing
//摘錄部分代碼：
"font-weight: bold; ">publicintinterceptKeyBeforeQueueing(longwhenNanos,intaction,intflags,
intkeyCode,intscanCode,intpolicyFlags,booleanisScreenOn) {
finalbooleandown = action == KeyEvent.ACTION_DOWN;
finalbooleancanceled = (flags & KeyEvent.FLAG_CANCELED) !=0;
finalbooleanisInjected = (policyFlags & WindowManagerPolicy.FLAG_INJECTED) !=0;
// If screen is off then we treat the case where the keyguard is open but hidden
// the same as if it were open and in front.
// This will prevent any keys other than the power button from waking the screen
// when the keyguard is hidden by another activity.
finalbooleankeyguardActive = (isScreenOn ?
mKeyguardMediator.isShowingAndNotHidden() :
mKeyguardMediator.isShowing());
intresult;//result即為傳回到wmaction
if(isScreenOn || isInjected) {
// When the screen is on or if the key is injected pass the key to the application.
result = ACTION_PASS_TO_USER;
} else{//我們現在走的應該是這個
// When the screen is off and the key is not injected, determine whether
// to wake the device but don't pass the key to the application.
result = 0;
finalbooleanisWakeKey = (policyFlags
& (WindowManagerPolicy.FLAG_WAKE | WindowManagerPolicy.FLAG_WAKE_DROPPED)) != 0;
if(down && isWakeKey) {
if(keyguardActive) {
//也就是說，如果目前螢幕是滅的，且按的鍵是可以喚醒螢幕的，那麼WM會首先将此次按鍵傳遞給keyguard，由keyguard來喚醒螢幕，并作出相應的動作，否則就自己點亮螢幕，通過傳回的policy來通知下層。
// If the keyguard is showing, let it decide what to do with the wake key.
"color:#ff0000;"> mKeyguardMediator.onWakeKeyWhenKeyguardShowingTq(keyCode);
} else{
// Otherwise, wake the device ourselves.
result |= ACTION_POKE_USER_ACTIVITY;
}
}
}"font-weight: bold; ">
....................
}
keyguarViewMediator.java onWakeKeyWhenKeyguardShowingTq
wakeWhenReadyLocked
mHandler.obtainMessage(WAKE_WHEN_READY, keyCode,
0);
mHandler.handleMessage
handleWakeWhenReady
mKeyguardViewManager.wakeWhenReadyTq
KeyguardViewManager.java mKeyguardView.wakeWhenReadyTq
LockpatternKeyguardView.java wakeWhenReadyTq
getCallback().pokeWakelock();
KeyguardViewMediator.java pokeWakelock
mWakeLock.acquire(); //mWakeLock即為：mWakeLock = mPM.newWakeLock(
PowerManager.FULL_WAKE_LOCK | PowerManager.ACQUIRE_CAUSES_WAKEUP,
"keyguard"); 具有ACQUIRE_CAUSE_WAKUPQ權限的喚醒鎖，上層就是通過此鎖來喚醒螢幕，接下來就是powermanager的流程了。
PowerManager.java acquire
mService.acquireWakeLock
PowermanagerService.java acquireWakeLock
acquireWakeLockLocked//此處會檢查喚醒鎖的标志位，作出對應的處理。
setPowerState //此函數為powermanager的核心函數之一，會對螢幕背光/喚醒，睡眠等作出相應的處理
setScreenStateLocked //此函數很關鍵
Power.setScreenState
power.java setScreenState
android_os_Power.cpp setScreenState
power.c set_screen_state//此函數作為上層的最後一個函數，會列印出标志性的log，*** set_screen_state %d，如果打出這個log，至少證明從APP-HAL都是在正常幹活的，那麼問題隻能是kernel的了，貼出代碼看看：
int
set_screen_state(inton)
{
//QEMU_FALLBACK(set_screen_state(on));
LOGI("*** set_screen_state %d", on);//神奇的log标志
initialize_fds();
//LOGI("go_to_sleep eventTime=%lld now=%lld g_error=%s\n", eventTime,
// systemTime(), strerror(g_error));
if(g_error)returng_error;
charbuf[32];
intlen;
if(on)
len = sprintf(buf, "%s", on_state);
else
len = sprintf(buf, "%s", off_state);
"color:#cc0000;">len = write(g_fds[REQUEST_STATE], buf, len);//此處就是寫了kernel的裝置檔案接口。
if(len
LOGE("Failed setting last user activity: g_error=%d\n", g_error);
}
return0;
}
在此函數中寫了底層的power控制的裝置檔案接口，對應的裝置檔案為：/sys/power/state
接下來的流程就是到了核心空間。
kernel/kernel/power/main.c state_store
//此函數被宏power_attr(state)聲明為裝置檔案接口 sys/power/state，宏power_attr的定義為(power.h)：
#define
power_attr(_name) \
static struct kobj_attribute _name##_attr = {\
.attr= {\
.name = __stringify(_name),\
.mode = 0644, \
},\
.show= _name##_show,\
.store = _name##_store,\
}
staticssize_t state_store(structkobject *kobj,structkobj_attribute *attr,
constchar*buf,size_tn)
{
#ifdef CONFIG_SUSPEND
#ifdef CONFIG_EARLYSUSPEND
suspend_state_t state = PM_SUSPEND_ON;
#else
suspend_state_t state = PM_SUSPEND_STANDBY;
#endif
constchar*const*s;
#endif
char*p;
intlen;
interror = -EINVAL;
p = memchr(buf, '\n', n);
len = p ? p - buf : n;
if(len == 4 && !strncmp(buf,"disk", len)) {
error = hibernate();
gotoExit;
}
#ifdef CONFIG_SUSPEND
for(s = &pm_states[state]; state
if(*s && len == strlen(*s) && !strncmp(buf, *s, len))
break;
}
printk("##: enter %s\n", pm_states[state]);
if(state
#ifdef CONFIG_EARLYSUSPEND // android對linux的睡眠喚醒機制做了一些優化，也就是earlysuspen,laterresume機制,此處宏是有定義的，是以會先走android的那一套
if(state == PM_SUSPEND_ON || valid_state(state)) {
error = 0;
printk("##: entering request_suspend_state()...\n");
request_suspend_state(state);
}
#else
error = enter_state(state);
#endif
#endif
Exit:
printk("##: state_store() returns back.\n");
returnerror ? error : n;
}
kernel/kernel/power/erlysuspend.c request_suspend_state
voidrequest_suspend_state(suspend_state_t new_state)
{
unsigned longirqflags;
intold_sleep;
powerkey_wdt_stop();
spin_lock_irqsave(&state_lock, irqflags);
old_sleep = state & SUSPEND_REQUESTED;
if(debug_mask & DEBUG_USER_STATE) {
structtimespec ts;
structrtc_timetm;
getnstimeofday(&ts);
rtc_time_to_tm(ts.tv_sec, &tm);
pr_info("request_suspend_state: %s (%d->%d) at %lld "
"(%d-%02d-%02d %02d:%02d:%02d.%09lu UTC)\n",
new_state != PM_SUSPEND_ON ? "sleep":"wakeup",
requested_suspend_state, new_state,
ktime_to_ns(ktime_get()),
tm.tm_year + 1900,tm.tm_mon + 1,tm.tm_mday,
tm.tm_hour,tm.tm_min,tm.tm_sec, ts.tv_nsec);
}
if(!old_sleep && new_state != PM_SUSPEND_ON) {
state |= SUSPEND_REQUESTED;
queue_work(suspend_work_queue, &early_suspend_work);
}"color: rgb(255, 0, 0); background-color: rgb(255, 255, 255);">"background-color: rgb(255, 255, 255); ">elseif(old_sleep && new_state == PM_SUSPEND_ON) {
state &= ~SUSPEND_REQUESTED;
wake_lock(&main_wake_lock); //acquire main ——wakelock
queue_work(suspend_work_queue, &late_resume_work); //将喚醒的work起來，開始執行之前聲明的late_resume_work
}
requested_suspend_state = new_state;
spin_unlock_irqrestore(&state_lock, irqflags);
}
而 之前有聲明static DECLARE_WORK(late_resume_work, late_resume); 故實際執行的函數是：late_resume。
kernel/kernel/power/erlysuspend.c late_resume
staticvoidlate_resume(structwork_struct *work)
{
structearly_suspend *pos;
unsigned longirqflags;
intabort = 0;
mutex_lock(&early_suspend_lock);
spin_lock_irqsave(&state_lock, irqflags);
if(state == SUSPENDED)
state &= ~SUSPENDED;
else
abort = 1;
spin_unlock_irqrestore(&state_lock, irqflags);
if(abort) {
if(debug_mask & DEBUG_SUSPEND)
pr_info("late_resume: abort, state %d\n", state);
gotoabort;
}
if(debug_mask & DEBUG_SUSPEND)
pr_info("late_resume: call handlers\n");
list_for_each_entry_reverse(pos, &early_suspend_handlers, link)
if(pos->resume != NULL) {
print_name_offset(NULL, pos->resume);
pos->resume(pos); //此處會調用到之前注冊了laterresume的drv的對應的函數，調用到fb_resume之後，螢幕就喚醒刷屏，螢幕上夜就有了資料，螢幕喚醒的流程就結束了。
}
if(debug_mask & DEBUG_SUSPEND)
pr_info("late_resume: done\n");
abort:
mutex_unlock(&early_suspend_lock);
}
總結： 螢幕點亮過程是由inputread捕獲後交由WM處理，由keyguard去申請喚醒鎖，powermanagerservice去調用kernel的喚醒的過程，其中彎彎繞還是比較多的，涉及的東西也很多，wakelock機制我還沒有搞的很清楚。
二、 螢幕睡眠
和螢幕喚醒的過程很類似，如下：
inputReader.cpp KeyboardInputMapper::processKey
getDispatcher()->notifyKey
inputDispacher.cpp InputDispatcher::notifyKey
mPolicy->interceptKeyBeforeQueueing
com_android_server_inputManager.cpp NativeInputManager::interceptKeyBeforeQueueing
InputManager.java interceptKeyBeforeQueueing
mWindowManagerService.mInputMonitor.interceptKeyBeforeQueueing
WindowmanagerService.java InputMonitor::interceptKeyBeforeQueueing
mPolicy.interceptKeyBeforeQueueing
PhonewindowManager.java interceptKeyBeforeQueueing
//同上面的分析，此處傳回的action是被或上了ACTION_GO_TO_SLEEP的(見1975行對
KeyEvent.KEYCODE_POWER的處理).......一級一級的傳回後.....
com_android_server_inputManager.cpp
NativeInputManager::interceptKeyBeforeQueueing
//傳回值中含有gotosleep的flag，故走到gotosleep分支
android_server_PowerManagerService_goToSleep
com_android_server_PowerManagerService.cpp
android_server_PowerManagerService_goToSleep
//同上面的inputmanager，此處也會調用到PowerManagerService的gotosleep,也是用
register_android_server_PowerManagerService方法來對應起來。
env->CallVoidMethod(gPowerManagerServiceObj,
gPowerManagerServiceClassInfo.goToSleep,
nanoseconds_to_milliseconds(eventTime));
PowermanagerService.java goToSleep
goToSleepWithReason
goToSleepLocked
setPowerState(SCREEN_OFF, false, reason);
setPowerState
setScreenStateLocked
Power.setScreenState(false)
power.java setScreenState
android_os_power.java setScreenState
power.c set_screen_state
kernel/kernel/power/main.c state_store
kernel/kernel/power/earlysuspend.c
request_suspend_state //此處流程和喚醒大同小異，不在贅述
early_suspend
staticvoidearly_suspend(structwork_struct *work)
{
structearly_suspend *pos;
unsigned longirqflags;
intabort = 0;
mutex_lock(&early_suspend_lock);
spin_lock_irqsave(&state_lock, irqflags);
if(state == SUSPEND_REQUESTED)
state |= SUSPENDED;
else
abort = 1;
spin_unlock_irqrestore(&state_lock, irqflags);
if(abort) {
if(debug_mask & DEBUG_SUSPEND)
pr_info("early_suspend: abort, state %d\n", state);
mutex_unlock(&early_suspend_lock);
gotoabort;
}
if(debug_mask & DEBUG_SUSPEND)
pr_info("early_suspend: call handlers\n");
list_for_each_entry(pos, &early_suspend_handlers, link) {
if(pos->suspend != NULL) {
print_name_offset(NULL, pos->suspend);
"background-color: rgb(204, 204, 204);">pos->suspend(pos);//調用注冊了earlysuspend的drv的suspend函數，調用到了fb_suspend，螢幕就會進入睡眠，睡眠的過程就結束了
}
}
mutex_unlock(&early_suspend_lock);
if(debug_mask & DEBUG_SUSPEND)
pr_info("early_suspend: sync\n");
//sys_sync();//let screen up faster
abort:
spin_lock_irqsave(&state_lock, irqflags);
if(state == SUSPEND_REQUESTED_AND_SUSPENDED)
wake_unlock(&main_wake_lock); //earlysuspend完畢後，檢查目前是否還有wakelock是active狀态，如果沒有，則會進入深睡眠(linux的suspend)
spin_unlock_irqrestore(&state_lock, irqflags);
}
下面我們繼續跟下代碼，簡單看看earlysuspend到deepsleep的過程，從wake_unlock開始
kernel/kernel/power/wakelock.c wake_unlock
voidwake_unlock(structwake_lock *lock)
{
inttype;
unsigned longirqflags;
spin_lock_irqsave(&list_lock, irqflags);
type = lock->flags & WAKE_LOCK_TYPE_MASK;
#ifdef CONFIG_WAKELOCK_STAT
wake_unlock_stat_locked(lock, 0);
#endif
if(debug_mask & DEBUG_WAKE_LOCK)
pr_info("wake_unlock: %s\n", lock->name);
lock->flags &= ~(WAKE_LOCK_ACTIVE | WAKE_LOCK_AUTO_EXPIRE);
list_del(&lock->link);
list_add(&lock->link, &inactive_locks);
if(type == WAKE_LOCK_SUSPEND) {
longhas_lock = has_wake_lock_locked(type);//判斷目前是否還有wake_lock是active的
if(has_lock > 0) {
if(debug_mask & DEBUG_EXPIRE)
pr_info("wake_unlock: %s, start expire timer, "
"%ld\n", lock->name, has_lock);
mod_timer(&expire_timer, jiffies + has_lock);
} else{
if(del_timer(&expire_timer))
if(debug_mask & DEBUG_EXPIRE)
pr_info("wake_unlock: %s, stop expire "
"timer\n", lock->name);
if(has_lock == 0) {
if(sprd_suspend_enable) {
queue_work(suspend_work_queue, &suspend_work); //起suspend_work，根據聲明，此處的work對應的函數即是suspend
}
}
}
if(lock == &main_wake_lock) {
if(debug_mask & DEBUG_SUSPEND)
print_active_locks(WAKE_LOCK_SUSPEND);
#ifdef CONFIG_WAKELOCK_STAT
update_sleep_wait_stats_locked(0);
#endif
}
}
spin_unlock_irqrestore(&list_lock, irqflags);
}
kernel/kernel/power/wakelock.c suspend
staticvoidsuspend(structwork_struct *work)
{
intret;
intentry_event_num;
add_pm_message(get_sys_cnt(), "suspend--enter: ", 0, 0, 0);
if(has_wake_lock(WAKE_LOCK_SUSPEND)) {
if(debug_mask & DEBUG_SUSPEND)
pr_info("suspend: abort suspend\n");
return;
}
entry_event_num = current_event_num;
sys_sync();
if(debug_mask & DEBUG_SUSPEND)
pr_info("suspend: enter suspend\n");
ret = pm_suspend(requested_suspend_state);
if(debug_mask & DEBUG_EXIT_SUSPEND) {
structtimespec ts;
structrtc_timetm;
getnstimeofday(&ts);
rtc_time_to_tm(ts.tv_sec, &tm);
pr_info("suspend: exit suspend, ret = %d "
"(%d-%02d-%02d %02d:%02d:%02d.%09lu UTC)\n", ret,
tm.tm_year + 1900,tm.tm_mon + 1,tm.tm_mday,
tm.tm_hour,tm.tm_min,tm.tm_sec, ts.tv_nsec);
}
if(current_event_num == entry_event_num) {
if(debug_mask & DEBUG_SUSPEND)
pr_info("suspend: pm_suspend returned with no event\n");
wake_lock_timeout(&unknown_wakeup, HZ / 2);
}
add_pm_message(get_sys_cnt(), "suspend--leave: ", 0, 0, 0);
}
kernel/kernel/power/suspend.c pm_suspend
intpm_suspend(suspend_state_t state)
{
if(state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX)
returnenter_state(state);//是不是和main.c裡的state_store函數中liunx的suspend一樣？豁然開朗。
return-EINVAL;
}
接下來就是linux的suspend了，沒有再仔細看過，慚愧慚愧。
總的來說，螢幕的睡眠是和上層的keyguard沒有關系，是在WM和PMS以及相關的JNI的配合下對kernel的操作完成的。
螢幕喚醒和睡眠就寫到這裡，而背光的點亮過程，大部分處理是在PMS中，是在HAL層操作了lights的裝置檔案并不涉及到喚醒和睡眠，顯得比較簡單，有時間也寫出來分享。