linux内核休眠、唤醒流程分析之挂起：pm.suspend_noirq（七）

最新推荐文章于 2022-08-03 10:15:56 发布

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最新推荐文章于 2022-08-03 10:15:56 发布 · 1.9k 阅读

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CC 4.0 BY-SA版权

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#linux #android

本文深入分析Linux内核挂起流程，详细讲解了通过dpm_suspend_noirq函数实现设备的suspend_noirq操作，包括状态复制、设备遍历、错误处理及链表迁移。此外，还探讨了如何判断并执行设备的电源管理操作，以及后续的CPU关闭、中断禁用、系统核心模块停用和进入休眠的步骤。

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 // kernel\power\suspend.c
 
/**
 * suspend_enter - Make the system enter the given sleep state.
 * @state: System sleep state to enter.
 * @wakeup: Returns information that the sleep state should not be re-entered.
 *
 * This function should be called after devices have been suspended.
 */
static int suspend_enter(suspend_state_t state, bool *wakeup)
{
   
   
	int error;

	error = platform_suspend_prepare(state);
	if (error)
		goto Platform_finish;

	error = dpm_suspend_late(PMSG_SUSPEND);
	if (error) {
   
   
		pr_err("late suspend of devices failed\n");
		goto Platform_finish;
	}
	error = platform_suspend_prepare_late(state);
	if (error)
		goto Devices_early_resume;

	error = dpm_suspend_noirq(PMSG_SUSPEND);
	if (error) {
   
   
		pr_err("noirq suspend of devices failed\n");
		goto Platform_early_resume;
	}
	error = platform_suspend_prepare_noirq(state);
	if (error)
		goto Platform_wake;

	if (suspend_test(TEST_PLATFORM))
		goto Platform_wake;

	if (state == PM_SUSPEND_TO_IDLE) {
   
   
		s2idle_loop();
		goto Platform_wake;
	}

	error = suspend_disable_secondary_cpus();
	if (error || suspend_test(TEST_CPUS))
		goto Enable_cpus;

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

	system_state = SYSTEM_SUSPEND;

	error = syscore_suspend();
	if (!error) {
   
   
		*wakeup = pm_wakeup_pending();
		if (!(suspend_test(TEST_CORE) || *wakeup)) {
   
   
			trace_suspend_resume(TPS("machine_suspend"),
				state, true);
			error = suspend_ops->enter(state);
			trace_suspend_resume(TPS("machine_suspend"),
				state, false);
		} else if (*wakeup) {
   
   
			error = -EBUSY;
		}
		syscore_resume(