pm runtime management_linuxpm runtime-优快云博客

本文链接：https://blog.youkuaiyun.com/wanggan267/article/details/46907155

本文详细介绍了Linux设备电源管理中pm_runtime的使用，包括pm_runtime介绍、设备字段、助手函数以及状态转换。重点讨论了rpm_resume、rpm_idle、rpm_suspend等函数的工作原理和应用场景，强调了电源管理的规则和提示。

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2. pm runtime introduction

2.1 pm_runtimedocumentation

Documentation/power/runtime_pm.txt

2.2 RuntimePM Device Fields

Common for runtime PM status:

.runtime_status = RPM_SUSPENDED;

.disable_depth = 1;

.runtime_error = 0;

.usage_count, 0);

.runtime_auto = true;

rpm_idle:

.idle_notification = false;

[wangshm5]For rpm_idle since no suspending/resuming statues to markthis feature in progress

For children:

power.child_count

.ingnor_children

For ASYNC mode:

.request_pending = false;

.request = RPM_REQ_NONE;

.deferred_resume = false;

For auto suspending feature:

.accounting_timestamp = jiffies;

.timer_expires = 0;

.last_busy -called after suspend immediately

.autosuspend_delay;

. use_autosuspend;

2.3 somepm_runtime helper function

2.3.1 rpm_resume

pm_runtime_resume(structdevice *dev) ó rpm_resume(dev,0)

pm_request_resume(structdevice *dev) ó rpm_resume(dev,RPM_ASYNC)

pm_runtime_get_sync(structdevice *dev) ó usage_count++;rpm_resume(dev,0)

pm_runtime_get(structdevice *dev) ó usage_count++;pm_resume(dev,RPM_ASYNC)

* If the resume callback returns an error code, the PMcore regards this as a fatal error and will refuse to run the helper functions until its status is directly set to either'active', or 'suspended' (by means ofspecial helper functions provided by the PM core for this purpose).

[wangshm5] NO -EBUSY or -EAGIAN, directlyother error code

* If->runtime_resume() is about to be executed or there's a pending request to execute it, the other callbacks will notbe executed for the same device.

* A request to execute->runtime_resume() will cancel any pending or scheduled requests to execute the othercallbacks for the same device, exceptfor scheduled autosuspends.

[wangshm5]Nearly future, IO operationneeded, so cancel other

2.3.2 Rpm_idle

pm_runtime_idle(struct device *dev) ó rpm_idle(dev,0)

pm_request_idle(struct device *dev) ó rpm_idle(dev,RPM_ASYNC)

pm_runtime_put_sync(structdevice *dev) ó usage_count--; ifusage_count != 0,return 0;rpm_idle(dev,0)

pm_runtime_put(structdevice *dev) ó usage_count--; ifusage_count != 0,return 0;rpm_idle(dev,RPM_ASYNC)

If there is no idle callback, or if the callback returns 0,then the PM core will attempt to carry out a runtime suspend of the device, alsorespecting devices configured for autosuspend.

Any pending request other than an idle notification takesprecedence over us, except that the timer may be running.

2.3.3 rpm_Suspend

pm_runtime_suspend(struct device *dev) ó rpm_suspend(dev,0)

pm_runtime_autosuspend(struct device *dev) ó rpm_suspend(dev,RPM_AUTO)

pm_request_autosuspend(struct device *dev) ó rpm_suspend(dev,RPM_ASYNC | RPM_AUTO)

pm_runtime_put_sync_suspend(struct device *dev) ó usage_count--; if usage_count != 0,return0;rpm_suspend(dev,0)

pm_runtime_put_sync_autosuspend(structdevice *dev) ó usage_count--; ifusage_count != 0,return 0;rpm_suspend(dev,RPM_AUTO)

pm_runtime_put_autosuspend(structdevice *dev) ó usage_count--; ifusage_count != 0,return 0;rpm_suspend(dev,RPM_ASYNC | RPM_AUTO)

[wangshm5] 默认的put是对应到idle的，加suspend才是对应到suspend的

[wangshm5]Nopm_runtime_put_suspend

2.3.4 irq_safe

By default, the callbacks are always invoked in processcontext with interrupts enabled (can sleep). However, the pm_runtime_irq_safe() helper function can be used to tellthe PM core that it is safe to run the ->runtime_suspend(),->runtime_resume() and ->runtime_idle() callbacks for the given device inatomic context with interrupts disabled.

2.3.5 Runtime rules

2.3.6 Tips

2.4 State Transaction

---------------------------------------------------20150720

SUSPEND without AUTO flag

	current status	SYNC	ASYNC	NOWAIT
rpm_ resume	ACTIVE	1(same)
	SUSPENDED	Callback (ACTIVE/SUSPENDED)	rpm_resume (dev,NOWAIT)	Callback (ACTIVE/SUSPENDED)
	SUSPENDING	SLEEP_WAIT_ RESTART¹	Mark Deferred resume ²(same)
	RESUMING	SLEEP_WAIT_ RESTART¹	EINPORGRESS(same)
rpm_ suspend	ACTIVE	Callback (ACTIVE/SUSPENDED)	rpm_suspend (dev,NOWAIT)	Callback (ACTIVE/SUSPENDED)
	SUSPENDED	1(same)
	SUSPENDING	SLEEP_WAIT_ RESTART	EINPROGRESS(same)
	RESUMING	EAGAIN(same)⁴ Not allowed this operation	rpm_suspend (dev,NOWAIT)	EAGIN(same)⁵ Not allowed this operation
rpm_ idle	ACTIVE && not idle notification	Callback rpm_suspend(SYNC)³	rpm_idle(dev, NOWAIT)	Callback rpm_suspend(SYNC)3
	ACTIVE && idle notification	EINPROGRESS(same)
	SUSPENDED	1(same)
	SUSPENDING	EAGAIN(same)
	RESUMING	EAGAIN(same)

Notice: Inthe bracket is device status

Same: devicestatus stay unchanged

EAGAIN: a kind oferror, we can refer it as this operation is not allowed

Red: when callback failed, the device status

Blue: queue_work to workqueue, and call rpm_xxx in columnASYNC in the near future.

Brown: If callback executed failed, ACTIVE; else it noidle callback or success then invoke rpm_suspend

1、SLEEP_WAIT _RESTART: sleep until theother thread which is do suspending or resuming operation change the statusand wakeup it to go to the beginning ofthe rpm_xxx to redo the code.

2、Whichimplicate rpm_resume(SYNC) will be called immediately after SUSPENDED inrpm_suspend

3、Assumecallback should execute successfully.

4、Whenyou use SYNC mode, the resume function return the device should be ACTIVE. And evenASYNC mode, resume operation will try its best to execute ->runtime_resumecallback function to wakeup the device;

5、rpm_suspendtry tosuspend the device, but it cannot guarantee after call the device status isSUSPENDED

6、rpm_idletry to call rpm_suspend function with SYNC flag, so it cannot guarantee aftercall the device status is SUSPENDED

7、resumeoperation is always take precedence over suspend operation.

8、Synchronoussuspends are not allowed when device is in RESUMING mode⁴

9、Asyncwork queue always only pending the last RMP_RQQUEST_XXX

10、 other scheduled or pending requests need to be canceled atthe beginning of rpm_suspend