linux内核休眠、唤醒流程分析之挂起：pm.suspend（五）

最新推荐文章于 2023-06-28 17:39:50 发布

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最新推荐文章于 2023-06-28 17:39:50 发布 · 1.1k 阅读

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#安卓 #linux

本文详细解析了Linux内核挂起流程中的dpm_suspend操作，包括复制状态到全局变量、遍历设备列表、执行设备挂起准备、处理失败情况以及设备链表转移等关键步骤。在设备挂起过程中，会根据dev->pm_domain->ops调用相应驱动的pm方法，若不存在则逐级向上查找type、class、bus的pm操作。

在这里插入图片描述

// devices\base\power\main.c

/**
 * dpm_suspend_start - Prepare devices for PM transition and suspend them.
 * @state: PM transition of the system being carried out.
 *
 * Prepare all non-sysdev devices for system PM transition and execute "suspend"
 * callbacks for them.
 */
int dpm_suspend_start(pm_message_t state)
{
   
   
	ktime_t starttime = ktime_get();
	int error;

	error = dpm_prepare(state);
	if (error) {
   
   
		suspend_stats.failed_prepare++;
		dpm_save_failed_step(SUSPEND_PREPARE);
	} else
		error = dpm_suspend(state);
	dpm_show_time(starttime, state, error, "start");
	return error;
}
EXPORT_SYMBOL_GPL(dpm_suspend_start);

然后调用dpm_suspend实现挂起流程，即流程图中的过程4。

// drivers\base\power\main.c

/**
 * dpm_suspend - Execute "suspend" callbacks for all non-sysdev devices.
 * @state: PM transition of the system being carried out.
 */
int dpm_suspend(pm_message_t state)
{
   
   
	ktime_t starttime = ktime_get();
	int error = 0;

	trace_suspend_resume(TPS("dpm_suspend"), state.event, true);
	might_sleep();

	devfreq_suspend();
	cpufreq_suspend();

	mutex_lock(&dpm_list_mtx);
	pm_transition = state;
	async_error = 0;
	while (!list_empty(&dpm_prepared_list)) {
   
   
		struct device *dev = to_device(dpm_prepared_list.prev);

		get_device(dev);
		mutex_unlock(&dpm_list_mtx);

		error = device_suspend(dev<

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