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