點擊打開鏈接

一：wakeup_source簡介：

?? ?linux 3.4內核PM使用了wakeup_source來保持喚醒狀態，也就是keep awake。之前android一直是基于Linux加入了wake_lock機制來阻止系統休眠，后來Linux 3.4內核加入了wakeup_source來管理，安卓4.4跟著升級內核也就摒棄了自己的臃腫的wake_lock機制，在對上層接口并不改變，在內核wake_lock實現直接基于wakeup_source來實現的。當然也會帶來debug上的一些問題，比如以前的wake_lock自身帶有強大的debug信息，那么我們在調試的時候可以自己看見dmesg中默認打印active wake lock XXX，很直觀來辨別需要休眠的時候那個wake lock有問題阻止了休眠。這個需要我們自己來完善。個人認為改進很大，現在使用了autosleep機制，只要不存在任何active wakeup_source了，系統自動休眠，當有active wake_source自動block住，個人認為休眠更及時，非休眠時間在減少，同時不會消耗額外的資源。使用基于queue work與進程block來管理suspend。還有這里的wakeup_source個人覺得應該叫keepawake_source或者stayawake_souce，畢竟系統的喚醒也就是cpu的再次運行是由中斷喚醒的而不是wakeup_source。同時安卓4.4還有一個重大改變就是去除了early suspend機制改為fb event通知機制。那么現在就只有suspend與resume,runtime suspend與runtime resume了。


/**
?* struct wakeup_source - Representation of wakeup sources
?*
?* @total_time: Total time this wakeup source has been active.
?* @max_time: Maximum time this wakeup source has been continuously active.
?* @last_time: Monotonic clock when the wakeup source's was touched last time.
?* @prevent_sleep_time: Total time this source has been preventing autosleep.
?* @event_count: Number of signaled wakeup events.
?* @active_count: Number of times the wakeup sorce was activated.
?* @relax_count: Number of times the wakeup sorce was deactivated.
?* @expire_count: Number of times the wakeup source's timeout has expired.
?* @wakeup_count: Number of times the wakeup source might abort suspend.
?* @active: Status of the wakeup source.
?* @has_timeout: The wakeup source has been activated with a timeout.
?*/
struct wakeup_source {
?? ?const char ?? ??? ?*name;
?? ?struct list_head?? ?entry;
?? ?struct list_head?? ?list;
?? ?spinlock_t?? ??? ?lock;
?? ?struct timer_list?? ?timer;
?? ?unsigned long?? ??? ?timer_expires; //超時時間，也就是wake_lock_timeout()里面的時間參數，超時后會執行deactivate函數
?? ?ktime_t total_time;
?? ?ktime_t max_time;
?? ?ktime_t last_time;
?? ?ktime_t start_prevent_time;
?? ?ktime_t prevent_sleep_time;
?? ?unsigned long?? ??? ?event_count; //event計數
?? ?unsigned long?? ??? ?active_count;//active計數
?? ?unsigned long?? ??? ?relax_count;
?? ?unsigned long?? ??? ?expire_count;
?? ?unsigned long?? ??? ?wakeup_count;
?? ?bool?? ??? ??? ?active:1; //用于判斷是否是active狀態
?? ?bool?? ??? ??? ?autosleep_enabled:1;//這個變量是來標記active等時間的
};


//active任何wakeup_source都會執行該函數，標記active為true
/**
?* wakup_source_activate - Mark given wakeup source as active.
?* @ws: Wakeup source to handle.
?*
?* Update the @ws' statistics and, if @ws has just been activated, notify the PM
?* core of the event by incrementing the counter of of wakeup events being
?* processed.
?*/
static void wakeup_source_activate(struct wakeup_source *ws)
{
?? ?unsigned int cec;

?? ?ws->active = true;
?? ?ws->active_count++;
?? ?ws->last_time = ktime_get();
?? ?if (ws->autosleep_enabled)
?? ??? ?ws->start_prevent_time = ws->last_time;

?? ?/* Increment the counter of events in progress. */
?? ?cec = atomic_inc_return(&combined_event_count);

?? ?trace_wakeup_source_activate(ws->name, cec);
}


//deactivate任何wakeup_source都會執行該函數，標記active為false
/**
?* wakup_source_deactivate - Mark given wakeup source as inactive.
?* @ws: Wakeup source to handle.
?*
?* Update the @ws' statistics and notify the PM core that the wakeup source has
?* become inactive by decrementing the counter of wakeup events being processed
?* and incrementing the counter of registered wakeup events.
?*/
static void wakeup_source_deactivate(struct wakeup_source *ws)
{
?? ?unsigned int cnt, inpr, cec;
?? ?ktime_t duration;
?? ?ktime_t now;

?? ?ws->relax_count++;
?? ?/*
?? ? * __pm_relax() may be called directly or from a timer function.
?? ? * If it is called directly right after the timer function has been
?? ? * started, but before the timer function calls __pm_relax(), it is
?? ? * possible that __pm_stay_awake() will be called in the meantime and
?? ? * will set ws->active.? Then, ws->active may be cleared immediately
?? ? * by the __pm_relax() called from the timer function, but in such a
?? ? * case ws->relax_count will be different from ws->active_count.
?? ? */
?? ?if (ws->relax_count != ws->active_count) {
?? ??? ?ws->relax_count--;
?? ??? ?return;
?? ?}

?? ?ws->active = false;

?? ?now = ktime_get();
?? ?duration = ktime_sub(now, ws->last_time);
?? ?ws->total_time = ktime_add(ws->total_time, duration);
?? ?if (ktime_to_ns(duration) > ktime_to_ns(ws->max_time))
?? ??? ?ws->max_time = duration;

?? ?ws->last_time = now;
?? ?del_timer(&ws->timer);
?? ?ws->timer_expires = 0;

?? ?if (ws->autosleep_enabled)
?? ??? ?update_prevent_sleep_time(ws, now);

?? ?/*
?? ? * Increment the counter of registered wakeup events and decrement the
?? ? * couter of wakeup events in progress simultaneously.
?? ? */
?? ?cec = atomic_add_return(MAX_IN_PROGRESS, &combined_event_count);
?? ?trace_wakeup_source_deactivate(ws->name, cec);

?? ?split_counters(&cnt, &inpr);
?? ?
?? ?if (!inpr && waitqueue_active(&wakeup_count_wait_queue)){
?? ??? ?wake_up(&wakeup_count_wait_queue); //當不存在任何active wake_up source的時候喚醒try_to_suspend進程。
?? ?}
?? ?
}

wakup_source的申請與釋放：
1：使用安卓的wake_lock接口：wake_lock（），wake_lock_timeout（）,wake_unlock（）;
2: 使用wakeup_source自帶的接口：pm_stay_awake（）,pm_relax();這里的name就是device name。

二：autosleep分析：

sys接口：sys/power/autosleep

亮屏時libsuspend會寫入off,滅屏寫入mem

static ssize_t autosleep_show(struct kobject *kobj,
?? ??? ??? ?????? struct kobj_attribute *attr,
?? ??? ??? ?????? char *buf)
{
?? ?suspend_state_t state = pm_autosleep_state();

?? ?if (state == PM_SUSPEND_ON)
?? ??? ?return sprintf(buf, "off\n");

#ifdef CONFIG_SUSPEND
?? ?if (state < PM_SUSPEND_MAX)
?? ??? ?return sprintf(buf, "%s\n", valid_state(state) ?
?? ??? ??? ??? ??? ??? ?pm_states[state] : "error");
#endif
#ifdef CONFIG_HIBERNATION
?? ?return sprintf(buf, "disk\n");
#else
?? ?return sprintf(buf, "error");
#endif
}

static ssize_t autosleep_store(struct kobject *kobj,
?? ??? ??? ??????? struct kobj_attribute *attr,
?? ??? ??? ??????? const char *buf, size_t n)
{
?? ?suspend_state_t state = decode_state(buf, n);
?? ?int error;

?? ?if (state == PM_SUSPEND_ON
?? ???? && strcmp(buf, "off") && strcmp(buf, "off\n"))
?? ??? ?return -EINVAL;

?? ?error = pm_autosleep_set_state(state);
?? ?return error ? error : n;
}

power_attr(autosleep);


int pm_autosleep_set_state(suspend_state_t state)
{

#ifndef CONFIG_HIBERNATION
?? ?if (state >= PM_SUSPEND_MAX)
?? ??? ?return -EINVAL;
#endif

?? ?__pm_stay_awake(autosleep_ws); //防止系統休眠?

?? ?mutex_lock(&autosleep_lock);

?? ?autosleep_state = state;

?? ?__pm_relax(autosleep_ws); //釋放上面的wake up source

?? ?if (state > PM_SUSPEND_ON) {
?? ??? ?pm_wakep_autosleep_enabled(true); //設置所有wake up source里面的autosleep_enabled為真，這個變量不會對休眠有影響，但是會標記active的時間,使用debugfs可以看見
?? ??? ?queue_up_suspend_work();//調度工作隊列，會執行try_to_suspend（），其實state mem執行try_to_suspend（），一次就可以了，后面再分析。
?? ?} else {
?? ??? ?pm_wakep_autosleep_enabled(false);//設置所有wake up source里面的autosleep_enabled為假
?? ?}

?? ?mutex_unlock(&autosleep_lock);
?? ?return 0;
}


重頭戲：try_to_suspend

static void try_to_suspend(struct work_struct *work)
{
?? ?unsigned int initial_count, final_count;

?? ?if (!pm_get_wakeup_count(&initial_count, true)) //獲取initial_count，這個函數會block住，當存在active wakeup source的時候，直到wakeup source為detative狀態
?? ??? ?goto out;

?? ?mutex_lock(&autosleep_lock);

?? ?if (!pm_save_wakeup_count(initial_count)) {//保存initial_count，不會block，當然也會檢查是否有active wakeup source，當有active存在再次queue work。
?? ??? ?mutex_unlock(&autosleep_lock);
?? ??? ?goto out;
?? ?}

?? ?if (autosleep_state == PM_SUSPEND_ON) {//當為ON狀態時，return。//在睡眠期間跟了很久沒有遇見過這種情況
?? ??? ?mutex_unlock(&autosleep_lock);
?? ??? ?return;
?? ?}
?? ?if (autosleep_state >= PM_SUSPEND_MAX)
?? ??? ?hibernate();????????????????? //hibernate高通平臺目前不支持
?? ?else
?? ??? ?pm_suspend(autosleep_state); //進入pm_suspend，dmesg會有PM: suspend entry 與PM: suspend exit來標記，這里面會執行freeze task,suspend與resume，disable cpu的操作。內核PM最重要的函數。

?? ?mutex_unlock(&autosleep_lock);

?? ?if (!pm_get_wakeup_count(&final_count, false))//獲取final_count，非block,當然也會檢查是否有active wakeup source，當有active存在再次queue work
?? ??? ?goto out;

?? ?/*
?? ? * If the wakeup occured for an unknown reason, wait to prevent the
?? ? * system from trying to suspend and waking up in a tight loop.
?? ? */
?? ?if (final_count == initial_count)???????????? //這里遇見未知原因，initial_count與final_count相等，超時500ms后繼續往下執行。這種現象我也是跟了許久沒有遇見過。
?? ??? ?schedule_timeout_uninterruptible(HZ / 2);

?out:
?? ?queue_up_suspend_work(); //調度queue work會再次執行該函數，實際上只要一次echo mem > sys/power/autosleep后這個進程一直會在auto_sleep cycle。
}


pm_get_wakeup_count原型,個人感覺這個是仿__wait_event_interruptible（）而寫的。

bool pm_get_wakeup_count(unsigned int *count, bool block)
{
?? ?unsigned int cnt, inpr;

?? ?if (block) { //當block為真時，該進程可能會block住
?? ??? ?DEFINE_WAIT(wait);

?? ??? ?for (;;) {
?? ??? ??? ?prepare_to_wait(&wakeup_count_wait_queue, &wait,
?? ??? ??? ??? ??? ?TASK_INTERRUPTIBLE);
?? ??? ??? ?split_counters(&cnt, &inpr); //有active的wakeup_source存在就是block住，否則block
?? ??? ??? ?if (inpr == 0 || signal_pending(current))
?? ??? ??? ??? ?break;
?? ??? ??? ?
?? ??? ??? ?schedule();//在這里面block住，直到最后一個active的wakeup_source deactivate時會喚醒該進程，之后會break出來。
?? ??? ?}
?? ??? ?finish_wait(&wakeup_count_wait_queue, &wait);
?? ?}

?? ?split_counters(&cnt, &inpr);
?? ?*count = cnt;
?? ?return !inpr;
}

那么有2個問題，按power鍵喚醒系統是退出try_to_suspend了嗎？
?????? 首先系統是如何被喚醒的？這個是由硬件中斷喚醒的，比如我們這里的power鍵，還有其他的比如alarm等其他硬件中斷，只要我們在中斷申請時enbale_irq_wake（）， 那么睡眠期間，只要觸發該中斷就可以喚醒系統。那么在try_to_suspend里面喚醒后pm_suspend（）執行完resume后會退出來，接著會獲取final_count，在這里是存在active ? wake_up source的（在out之前加添的打印active wakeup_source，下面的dmesg證明了存在的wakeup_source），之后執行out,后調度工作隊列，再次進入try_to_suspend（），在第一次獲取initial_count后便會遇見active wakeup_source，這里面更多的是系統上層加的wakeup_source，那么try_to_suspend()會一直block在pm_get_wakeup_count()里面直到滅屏和所有wakeup_source deactivate時會再次進入pm_suspend（）休眠。
?????? 這里也就解釋了為什么只要執行一次ehco mem > sys/power/autosleep后自動可以休眠了的原因。

看下面的dmesg:
<6>[? 928.536418] CPU0: msm_cpu_pm_enter_sleep mode 000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000
<6>[? 928.543066] PM: noirq resume of devices complete after 6.020 msecs
<6>[? 928.548512] PM: early resume of devices complete after 2.598 msecs
<6>[? 928.650793] PM: resume of devices complete after 102.266 msecs
<6>[? 928.660290] Restarting tasks ... done.
<6>[? 928.681208] PM: suspend exit 1970-01-05 05:23:32.206389881 UTC
<6>[? 928.681229] active wake lock KeyEvents
<6>[? 928.681267] active wake lock qpnp_soc_wake
<6>[? 928.681284] active wake lock alarm, time left 486
<6>[? 928.681342] active wake lock KeyEvents
<6>[? 928.681584] active wake lock qpnp_soc_wake
<6>[? 928.681600] active wake lock alarm, time left 486
<6>[? 928.696345] request_suspend_state: wakeup at 928691792356 (1970-01-05 05:23:32.221521704 UTC)
<6>[? 928.708608] mdss_dsi_panel_power on=1



還有一個與wakeup source無關的問題,為什么suspend后就一直停留在那里不動了？
?????? 這個是cpu停止運轉了，下面再分析下代碼。
?????? 核心函數suspend_devices_and_enter（）：

/**
?* suspend_devices_and_enter - Suspend devices and enter system sleep state.
?* @state: System sleep state to enter.
?*/
int suspend_devices_and_enter(suspend_state_t state)
{
?? ?int error;
?? ?bool wakeup = false;

?? ?if (!suspend_ops)
?? ??? ?return -ENOSYS;

?? ?trace_machine_suspend(state);
?? ?if (suspend_ops->begin) {
?? ??? ?error = suspend_ops->begin(state);
?? ??? ?if (error)
?? ??? ??? ?goto Close;
?? ?}
?? ?suspend_console();
?? ?suspend_test_start();
?? ?error = dpm_suspend_start(PMSG_SUSPEND);//這里會執行所有driver的suspend函數，suspend里面有active wakeup_source或者return 為真的話，suspend會報錯
?? ?if (error) {
?? ??? ?printk(KERN_ERR "PM: Some devices failed to suspend\n");
?? ??? ?goto Recover_platform;
?? ?}
?? ?suspend_test_finish("suspend devices");
?? ?if (suspend_test(TEST_DEVICES))
?? ??? ?goto Recover_platform;

?? ?do {
?? ??? ?error = suspend_enter(state, &wakeup);//這里會diable cpu
?? ?} while (!error && !wakeup
?? ??? ?&& suspend_ops->suspend_again && suspend_ops->suspend_again());

?Resume_devices:
?? ?suspend_test_start();
?? ?dpm_resume_end(PMSG_RESUME);
?? ?suspend_test_finish("resume devices");
?? ?resume_console();
?Close:
?? ?if (suspend_ops->end)
?? ??? ?suspend_ops->end();
?? ?trace_machine_suspend(PWR_EVENT_EXIT);
?? ?return error;

?Recover_platform:
?? ?if (suspend_ops->recover)
?? ??? ?suspend_ops->recover();
?? ?goto Resume_devices;
}


static int suspend_enter(suspend_state_t state, bool *wakeup)
{
?? ?int error;

?? ?if (suspend_ops->prepare) {
?? ??? ?error = suspend_ops->prepare();
?? ??? ?if (error)
?? ??? ??? ?goto Platform_finish;
?? ?}

?? ?error = dpm_suspend_end(PMSG_SUSPEND);
?? ?if (error) {
?? ??? ?printk(KERN_ERR "PM: Some devices failed to power down\n");
?? ??? ?goto Platform_finish;
?? ?}

?? ?if (suspend_ops->prepare_late) {
?? ??? ?error = suspend_ops->prepare_late();
?? ??? ?if (error)
?? ??? ??? ?goto Platform_wake;
?? ?}

?? ?if (suspend_test(TEST_PLATFORM))
?? ??? ?goto Platform_wake;

?? ?error = disable_nonboot_cpus();? //disable nonboot cpu注意還有cpu需要下面disable的
?? ?if (error || suspend_test(TEST_CPUS))
?? ??? ?goto Enable_cpus;

?? ?arch_suspend_disable_irqs();
?? ?BUG_ON(!irqs_disabled());

?? ?error = syscore_suspend();
?? ?if (!error) {
?? ??? ?*wakeup = pm_wakeup_pending();
?? ??? ?if (!(suspend_test(TEST_CORE) || *wakeup)) {
?? ??? ??? ?error = suspend_ops->enter(state); //在這里cpu會停止運行，直到中斷喚醒
//下面的全部是喚醒的操作了
?? ??? ??? ?events_check_enabled = false;
?? ??? ?}
?? ??? ?syscore_resume();
?? ?}

?? ?arch_suspend_enable_irqs();
?? ?BUG_ON(irqs_disabled());

?Enable_cpus:
?? ?enable_nonboot_cpus();

?Platform_wake:
?? ?if (suspend_ops->wake)
?? ??? ?suspend_ops->wake();

?? ?dpm_resume_start(PMSG_RESUME);

?Platform_finish:
?? ?if (suspend_ops->finish)
?? ??? ?suspend_ops->finish();

?? ?return error;
}

平臺賦值，這里debug平臺是基于msm8974的：
static const struct platform_suspend_ops lpm_suspend_ops = {
?? ?.enter = lpm_suspend_enter,//在這里面disbale cpu，停止運行程序
?? ?.valid = suspend_valid_only_mem,
?? ?.prepare_late = lpm_suspend_prepare,
?? ?.wake = lpm_suspend_wake,
};


添加顯示wake_lock的dmesg:
<6>[?? 90.964850] CPU0: msm_cpu_pm_enter_sleep mode 000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000
<6>[?? 90.965302] Enabling non-boot CPUs ...
<6>[?? 90.968303] CPU3 is up
<6>[?? 90.970699] PM: noirq resume of devices complete after 2.382 msecs
<6>[?? 90.973460] PM: early resume of devices complete after 1.443 msecs
<6>[?? 91.097369] PM: resume of devices complete after 123.888 msecs
<6>[?? 91.112858] Restarting tasks ... done.
<6>[?? 91.141699] PM: suspend exit 1970-01-05 03:59:28.158266979 UTC
<6>[?? 91.141776] PM: suspend entry 1970-01-05 03:59:28.158347917 UTC
<6>[?? 91.141801] PM: Syncing filesystems ... done.
<6>[?? 91.222299] Freezing user space processes ... (elapsed 0.03 seconds) done.
<6>[?? 91.258126] Freezing remaining freezable tasks ... (elapsed 0.02 seconds) done.
<6>[?? 91.278279] Suspending console(s) (use no_console_suspend to debug)
<6>[?? 91.384933] PM: suspend of devices complete after 95.062 msecs
<6>[?? 91.397910] PM: late suspend of devices complete after 12.934 msecs
<6>[?? 91.413019] PM: noirq suspend of devices complete after 15.064 msecs
<6>[?? 91.413059] Disabling non-boot CPUs ...
<6>[?? 91.424477] CPU0: msm_cpu_pm_enter_sleep mode 000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000//這里cpu停止運行直到中斷喚醒
<6>[?? 91.425144] Enabling non-boot CPUs ...
<6>[?? 91.432354] CPU3 is up
<6>[?? 91.444416] PM: noirq resume of devices complete after 11.997 msecs
<6>[?? 91.460948] PM: early resume of devices complete after 10.458 msecs
<6>[?? 91.577213] PM: resume of devices complete after 116.231 msecs
<6>[?? 91.584876] Restarting tasks ... done.
<6>[?? 91.614571] PM: suspend exit 1970-01-05 03:59:35.550203849 UTC
<6>[?? 91.614639] active wake lock rmt_storage_-1220268312
<6>[?? 91.689912] PM: suspend entry 1970-01-05 03:59:35.625550620 UTC
<6>[?? 91.689921] PM: Syncing filesystems ... done.
<6>[?? 91.700706] Freezing user space processes ...?
<3>[?? 91.712870] Freezing of user space? aborted
<6>[?? 91.712898]?
<6>[?? 91.712903] Restarting tasks ... done.
<6>[?? 91.720540] PM: suspend exit 1970-01-05 03:59:35.656175256 UTC
<6>[?? 91.720574] PM: suspend entry 1970-01-05 03:59:35.656214579 UTC
<6>[?? 91.720586] PM: Syncing filesystems ... done.
<6>[?? 91.801097] Freezing user space processes ...?
<3>[?? 91.815050] Freezing of user space? aborted
<6>[?? 91.815075]?
<6>[?? 91.815083] Restarting tasks ... done.
<6>[?? 91.823603] PM: suspend exit 1970-01-05 03:59:35.759241558 UTC
<6>[?? 91.823633] PM: suspend entry 1970-01-05 03:59:35.759272964 UTC
<6>[?? 91.823643] PM: Syncing filesystems ... done.
<6>[?? 91.911985] Freezing user space processes ... (elapsed 0.03 seconds) done.
<6>[?? 91.949378] Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
<6>[?? 91.969089] Suspending console(s) (use no_console_suspend to debug)
<6>[?? 92.085594] PM: suspend of devices complete after 98.499 msecs
<6>[?? 92.098615] PM: late suspend of devices complete after 12.975 msecs
<6>[?? 92.113909] PM: noirq suspend of devices complete after 15.249 msecs
<6>[?? 92.113951] Disabling non-boot CPUs ...
<6>[?? 92.147320] CPU0: msm_cpu_pm_enter_sleep mode 000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000
<6>[?? 92.148265] Enabling non-boot CPUs ...
<6>[?? 92.155121] CPU1 is up
<6>[?? 92.163797] CPU2 is up
<6>[?? 92.174144] CPU3 is up
<6>[?? 92.186556] PM: noirq resume of devices complete after 12.344 msecs
<6>[?? 92.199945] PM: early resume of devices complete after 10.020 msecs
<6>[?? 92.317528] PM: resume of devices complete after 117.548 msecs
<6>[?? 92.326254] Restarting tasks ... done.
<6>[?? 92.342025] PM: suspend exit 1970-01-05 04:00:48.122436614 UTC
<6>[?? 92.342337] active wake lock qpnp-vadc-f611ac00
<6>[?? 92.342357] active wake lock alarm, time left 481
<6>[?? 92.411428] PM: suspend entry 1970-01-05 04:00:48.191838905 UTC
<6>[?? 92.411451] PM: Syncing filesystems ... done.
<6>[?? 92.419086] Freezing user space processes ...?
<3>[?? 92.431173] Freezing of user space? aborted
<6>[?? 92.431213]?
<6>[?? 92.431225] Restarting tasks ... done.
<6>[?? 92.441575] PM: suspend exit 1970-01-05 04:00:48.221987864 UTC
<6>[?? 92.441709] active wake lock qpnp-vadc-f611ac00
<6>[?? 92.445004] PM: suspend entry 1970-01-05 04:00:48.225417551 UTC
<6>[?? 92.445026] PM: Syncing filesystems ... done.
<6>[?? 92.525764] Freezing user space processes ...?
<3>[?? 92.541465] Freezing of user space? aborted
<6>[?? 92.541523]?
<6>[?? 92.541545] Restarting tasks ... done.
<6>[?? 92.558768] PM: suspend exit 1970-01-05 04:00:48.339166145 UTC
<6>[?? 92.558865] PM: suspend entry 1970-01-05 04:00:48.339268645 UTC
<6>[?? 92.558898] PM: Syncing filesystems ... done.
<6>[?? 92.656122] Freezing user space processes ... (elapsed 0.04 seconds) done.
<6>[?? 92.699091] Freezing remaining freezable tasks ... (elapsed 0.01 seconds) done.
<6>[?? 92.718891] Suspending console(s) (use no_console_suspend to debug)
<6>[?? 92.832084] PM: suspend of devices complete after 97.905 msecs
<6>[?? 92.845099] PM: late suspend of devices complete after 12.971 msecs
<6>[?? 92.860407] PM: noirq suspend of devices complete after 15.264 msecs
<6>[?? 92.860447] Disabling non-boot CPUs ...
<6>[?? 92.895114] CPU0: msm_cpu_pm_enter_sleep mode 000000,00000000,00000000,00000000,00000000,00000020,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000

總結

以上是生活随笔為你收集整理的linux内核3.4基于wakeup_source的autosleep机制分析的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。