kernel suspend

mstar_pm_enter

PM Power Down

N

enter_state/*off mem sleep state*/

enter_state/*mem sleep state*/

If Not wakeup event

Freeze User Space and Kernel Process

early_suspend

early_resume

Y

PowerManagerService/*request wakeup by user*/

注意：休眠过程：这个只是简化的流程，实际还需要考虑很多情况，整个绿色标示过程中用户都有可能按下遥控器PowerKey或者触发其他wakeup event，都将导致系统完全唤醒，或者该过程遇到错误，系统后台局部唤醒然后等待条件满足重新执行suspend。该过程执行的时间是不确定的。wakeup event是由wakeup source产生，系统指定的wakeup source不会被suspend唤醒过程：类似，由PowerManagerService向节点/sys/power/state写入off终止休眠

suspend devices

PowerManagerService/*request sleep by user*/

resume devices

If has wakeup evnet or freeze process failed

exitStrMode

thaw all processes

enterStrMode/*echo mem /sys/power/state*/

If has wake_lock

If has wake up event or suspend failed

Kernel Mode