linux 休眠唤醒中设备、总线、用户进程、内核线程调试分析流程

一、suspending consoles打印

代码位置:Kernel/power/suspend.c

函数调用流程:devices_and_enter(suspend_state_t state) --> suspend_console();

void suspend_console(void)

{

if (!console_suspend_enabled) 注释这一行,可以看到休眠后printk的打印

return;

printk("Suspending console(s) (use no_console_suspend to debug)\n");

console_lock();

console_suspended = 1;

up(&console_sem);

}

二、打印linux 内核 bus总线休眠唤醒流程

代码位置:Kernel/drivers/base/power/main.c

dpm_suspend() --> device_suspend() --> __device_suspend()

修改位置:

static void pm_dev_dbg(struct device *dev, pm_message_t state, char *info)
{
    dev_printk(KERN_ERR,dev, "%s%s%s\n", info, pm_verb(state.event),
        ((state.event & PM_EVENT_SLEEP) && device_may_wakeup(dev)) ?
        ", may wakeup" : "");
}

内核 log如下:

bus suspend:

[ 329.576315] reg-fixed-voltage soc:emac_lan_vreg: bus suspend

[ 329.581997] reg-fixed-voltage soc:rome_vreg: bus suspend

[ 329.587245] reg-fixed-voltage soc:sdcard_ext_vreg: bus suspend

[ 329.593177] qcom,mem-acc-regulator 1942131.regulator: bus suspend

[ 329.599144] pps-gpio soc:pps: bus suspend

[ 329.603183] platform 7c50000.qcom,emac: bus suspend

bus resume:

[ 331.355074] msm_serial_hs 98b1000.uart: noirq driver resume

[ 331.361022] PM: noirq resume of devices complete after 17.017 msecs

[ 331.367635] PM: early resume of devices complete after 0.543 msecs

[ 331.372985] reg-dummy reg-dummy: bus resume

三、设备休眠唤醒流程打印

代码位置:driver/base/platform.c

3.1 linux设备休眠流程:

int platform_pm_suspend(struct device *dev)
{
struct device_driver *drv = dev->driver;
int ret = 0;
...
...

if (drv->pm) {
if (drv->pm->suspend)
ret = drv->pm->suspend(dev);
+pr_info("%s called name = %s\n", __func__, drv->name); //此处添加suspend 设备调试打印
} else {
ret = platform_legacy_suspend(dev, PMSG_SUSPEND);
}

3.2 linux设备唤醒流程

int platform_pm_resume(struct device *dev)
{
struct device_driver *drv = dev->driver;
int ret = 0;

...
...

if (drv->pm) {
if (drv->pm->resume)
ret = drv->pm->resume(dev);
pr_info("%s called name = %s\n", __func__, drv->name);//此处添加设备resume打印
} else {
ret = platform_legacy_resume(dev);
}

四、linux内核线程和进程休眠过程打印

函数调用流程:

enter_state(suspend.c)--->suspend_prepare--->suspend_freeze_processes()--->freeze_processes(--->try_to_freeze_tasks--->freeze_task)--->freeze_kernel_processes

可以在kernel/power/process.c中添加如下打印:

for_each_process_thread(g,p)

...

pr_info("userspace pid %d, %d\n", p->pid, current->pid);

...

打印效果如下:

[ 327.812216] PM: suspend entry 2018-09-18 11:53:17.879150194 UTC

[ 327.817117] PM: Syncing filesystems ... done.

[ 327.823632] Freezing user space processes ... userspace pid 1

[ 327.828524] userspace pid 6

[ 327.831545] userspace pid 124

[ 327.834264] userspace pid 1345

[ 327.837216] userspace pid 2150

对于内核线程休眠的打印可以参考上面在freeze_kernel_processes中添加打印。

五、late_resume和earlysuspend.c加打印

在部分内核版本中可以添加如下log分析问题:

late_resume函数中:

list_for_each_entry_reverse(pos, &early_suspend_handlers, link)

if (pos->resume != NULL) {

pos->resume(pos);

+pr_info("late_resume: func %p\n",pos->resume);

}

early_suspend late_resume添加log

在earlysuspend.c中

static int debug_mask = DEBUG_USER_STATE;

->

static int debug_mask = DEBUG_USER_STATE | DEBUG_SUSPEND |

DEBUG_VERBOSE;

六、休眠唤醒时间长问题排查

参见之前调试文档说明,链接如下:

休眠唤醒(suspend/resume)时长问题分析思路_sched_clock_suspend-CSDN博客

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