---
title: acknowledgePowerChange
framework: kernel
role: pseudoSymbol
path: kernel/ioservice/1809710-acknowledgepowerchange
---

# acknowledgePowerChange

Acknowledges an in-progress power state change.

## Declaration

```occ
IOReturn acknowledgePowerChange(
 IOService *whichDriver ); 
```

## Parameters

- `whichDriver`: A pointer to the calling driver. The called object tracks all interested parties to ensure that all have acknowledged the power state change.

## Return Value

Return Value IOPMNoErr.

## Overview

Overview When power management informs an interested object (via powerStateWillChangeTo or powerStateDidChangeTo), the object can return an immediate acknowledgement via a return code, or it may return an indication that it will acknowledge later by calling acknowledgePowerChange. Interested objects are those that have registered as interested drivers, as well as power plane children of the power changing driver. A driver that calls registerInterestedDriver must call acknowledgePowerChange, or use an immediate acknowledgement return from powerStateWillChangeTo or powerStateDidChangeTo.

## See Also

### Miscellaneous

- [acknowledgeSetPowerState](kernel/ioservice/1532596-acknowledgesetpowerstate.md)
- [activityTickle](kernel/ioservice/1809731-activitytickle.md)
- [addLocation](kernel/ioservice/1809740-addlocation.md)
- [addMatchingNotification](kernel/ioservice/1809749-addmatchingnotification.md)
- [addNotification](kernel/ioservice/1809760-addnotification.md)
- [addPowerChild](kernel/ioservice/1809766-addpowerchild.md)
- [adjustBusy](kernel/ioservice/1809776-adjustbusy.md)
- [attach](kernel/ioservice/1809786-attach.md)
- [callPlatformFunction](kernel/ioservice/1809795-callplatformfunction.md)
- [causeInterrupt](kernel/ioservice/1809803-causeinterrupt.md)
- [changePowerStateTo](kernel/ioservice/1809809-changepowerstateto.md)
- [changePowerStateToPriv](kernel/ioservice/1809819-changepowerstatetopriv.md)
- [clampPowerOn](kernel/ioservice/1809824-clamppoweron.md)
- [close](kernel/ioservice/1809831-close.md)
- [command_received](kernel/ioservice/1809840-command_received.md)
- [compareProperties](kernel/ioservice/1809848-compareproperties.md)
- [compareProperty(OSDictionary *, const char *)](kernel/ioservice/1809855-compareproperty.md)
- [compareProperty(OSDictionary *, const OSString *)](kernel/ioservice/1809861-compareproperty.md)
- [configureReport](kernel/ioservice/1809870-configurereport.md)
- [copyClientWithCategory](kernel/ioservice/1809878-copyclientwithcategory.md)
- [copyMatchingService](kernel/ioservice/1809887-copymatchingservice.md)
- [currentCapability](kernel/ioservice/1809891-currentcapability.md)
- [currentPowerConsumption](kernel/ioservice/1809899-currentpowerconsumption.md)
- [deRegisterInterestedDriver](kernel/ioservice/1809905-deregisterinteresteddriver.md)
- [detach](kernel/ioservice/1809913-detach.md)
- [didTerminate](kernel/ioservice/1809918-didterminate.md)
- [didYouWakeSystem](kernel/ioservice/1809924-didyouwakesystem.md)
- [disableInterrupt](kernel/ioservice/1809929-disableinterrupt.md)
- [enableInterrupt](kernel/ioservice/1809937-enableinterrupt.md)
- [errnoFromReturn](kernel/ioservice/1809942-errnofromreturn.md)
- [finalize](kernel/ioservice/1809948-finalize.md)
- [free](kernel/ioservice/1809960-free.md)
- [getAggressiveness](kernel/ioservice/1809962-getaggressiveness.md)
- [getBusyState](kernel/ioservice/1809968-getbusystate.md)
- [getClient](kernel/ioservice/1809973-getclient.md)
- [getClientIterator](kernel/ioservice/1809979-getclientiterator.md)
- [getDeviceMemory](kernel/ioservice/1809984-getdevicememory.md)
- [getDeviceMemoryCount](kernel/ioservice/1809990-getdevicememorycount.md)
- [getDeviceMemoryWithIndex](kernel/ioservice/1809999-getdevicememorywithindex.md)
- [getInterruptType](kernel/ioservice/1810004-getinterrupttype.md)
- [getMatchingServices](kernel/ioservice/1810011-getmatchingservices.md)
- [getOpenClientIterator](kernel/ioservice/1810018-getopenclientiterator.md)
- [getOpenProviderIterator](kernel/ioservice/1810027-getopenprovideriterator.md)
- [getPlatform](kernel/ioservice/1810033-getplatform.md)
- [getPMRootDomain](kernel/ioservice/1810046-getpmrootdomain.md)
- [getPMworkloop](kernel/ioservice/1810059-getpmworkloop.md)
- [getPowerState](kernel/ioservice/1810074-getpowerstate.md)
- [getProvider](kernel/ioservice/1810088-getprovider.md)
- [getProviderIterator](kernel/ioservice/1810097-getprovideriterator.md)
- [getResources](kernel/ioservice/1810107-getresources.md)
- [getResourceService](kernel/ioservice/1810116-getresourceservice.md)
- [getServiceRoot](kernel/ioservice/1810122-getserviceroot.md)
- [getState](kernel/ioservice/1810137-getstate.md)
- [getWorkLoop](kernel/ioservice/1810145-getworkloop.md)
- [handleClose](kernel/ioservice/1810153-handleclose.md)
- [handleIsOpen](kernel/ioservice/1810164-handleisopen.md)
- [handleOpen](kernel/ioservice/1810174-handleopen.md)
- [initialPowerStateForDomainState](kernel/ioservice/1810182-initialpowerstatefordomainstate.md)
- [isInactive](kernel/ioservice/1810198-isinactive.md)
- [isOpen](kernel/ioservice/1810209-isopen.md)
- [joinPMtree](kernel/ioservice/1810216-joinpmtree.md)
- [lockForArbitration](kernel/ioservice/1810228-lockforarbitration.md)
- [makeUsable](kernel/ioservice/1810246-makeusable.md)
- [mapDeviceMemoryWithIndex](kernel/ioservice/1810261-mapdevicememorywithindex.md)
- [matchLocation](kernel/ioservice/1810275-matchlocation.md)
- [matchPropertyTable](kernel/ioservice/1810286-matchpropertytable.md)
- [maxCapabilityForDomainState](kernel/ioservice/1810302-maxcapabilityfordomainstate.md)
- [message](kernel/ioservice/1810323-message.md)
- [messageClient](kernel/ioservice/1810334-messageclient.md)
- [messageClients](kernel/ioservice/1810353-messageclients.md)
- [nameMatching(const char *, OSDictionary *)](kernel/ioservice/1810365-namematching.md)
- [nameMatching(const OSString *, OSDictionary *)](kernel/ioservice/1810383-namematching.md)
- [newTemperature](kernel/ioservice/1810402-newtemperature.md)
- [newUserClient](kernel/ioservice/1810417-newuserclient.md)
- [nextIdleTimeout](kernel/ioservice/1810435-nextidletimeout.md)
- [open](kernel/ioservice/1810450-open.md)
- [PM_Clamp_Timer_Expired](kernel/ioservice/1810463-pm_clamp_timer_expired.md)
- [PM_idle_timer_expiration](kernel/ioservice/1810474-pm_idle_timer_expiration.md)
- [PMinit](kernel/ioservice/1810486-pminit.md)
- [PMstop](kernel/ioservice/1810502-pmstop.md)
- [powerChangeDone](kernel/ioservice/1810518-powerchangedone.md)
- [powerOverrideOffPriv](kernel/ioservice/1810533-poweroverrideoffpriv.md)
- [powerOverrideOnPriv](kernel/ioservice/1810549-poweroverrideonpriv.md)
- [powerStateDidChangeTo](kernel/ioservice/1810564-powerstatedidchangeto.md)
- [powerStateForDomainState](kernel/ioservice/1810576-powerstatefordomainstate.md)
- [powerStateWillChangeTo](kernel/ioservice/1810597-powerstatewillchangeto.md)
- [probe](kernel/ioservice/1810605-probe.md)
- [propertyMatching](kernel/ioservice/1810622-propertymatching.md)
- [publishResource(const char *, OSObject *)](kernel/ioservice/1810642-publishresource.md)
- [publishResource(const OSSymbol *, OSObject *)](kernel/ioservice/1810661-publishresource.md)
- [registerInterestedDriver](kernel/ioservice/1810675-registerinteresteddriver.md)
- [registerInterrupt](kernel/ioservice/1810691-registerinterrupt.md)
- [registerPowerDriver](kernel/ioservice/1810706-registerpowerdriver.md)
- [registerService](kernel/ioservice/1810726-registerservice.md)
- [registryEntryIDMatching](kernel/ioservice/1810750-registryentryidmatching.md)
- [removePowerChild](kernel/ioservice/1810770-removepowerchild.md)
- [requestPowerDomainState](kernel/ioservice/1810786-requestpowerdomainstate.md)
- [requestProbe](kernel/ioservice/1810804-requestprobe.md)
- [requestTerminate](kernel/ioservice/1810819-requestterminate.md)
- [resourceMatching(const char *, OSDictionary *)](kernel/ioservice/1810840-resourcematching.md)
- [resourceMatching(const OSString *, OSDictionary *)](kernel/ioservice/1810857-resourcematching.md)
- [serviceMatching(const char *, OSDictionary *)](kernel/ioservice/1810880-servicematching.md)
- [serviceMatching(const OSString *, OSDictionary *)](kernel/ioservice/1810901-servicematching.md)
- [setAggressiveness](kernel/ioservice/1810925-setaggressiveness.md)
- [setDeviceMemory](kernel/ioservice/1810946-setdevicememory.md)
- [setIdleTimerPeriod](kernel/ioservice/1810962-setidletimerperiod.md)
- [setPowerParent](kernel/ioservice/1810987-setpowerparent.md)
- [setPowerState](kernel/ioservice/1532866-setpowerstate.md)
- [start](kernel/ioservice/1811009-start.md)
- [start_PM_idle_timer](kernel/ioservice/1811024-start_pm_idle_timer.md)
- [stop](kernel/ioservice/1811034-stop.md)
- [stringFromReturn](kernel/ioservice/1811046-stringfromreturn.md)
- [systemWake](kernel/ioservice/1811056-systemwake.md)
- [systemWillShutdown](kernel/ioservice/1811071-systemwillshutdown.md)
- [temperatureCriticalForZone](kernel/ioservice/1811087-temperaturecriticalforzone.md)
- [temporaryPowerClampOn](kernel/ioservice/1811099-temporarypowerclampon.md)
- [terminate](kernel/ioservice/1811110-terminate.md)
- [terminateClient](kernel/ioservice/1811121-terminateclient.md)
- [unlockForArbitration](kernel/ioservice/1811130-unlockforarbitration.md)
- [unregisterInterrupt](kernel/ioservice/1811142-unregisterinterrupt.md)
- [updateReport](kernel/ioservice/1811152-updatereport.md)
- [waitForMatchingService](kernel/ioservice/1811164-waitformatchingservice.md)
- [waitForService](kernel/ioservice/1811172-waitforservice.md)
- [waitQuiet](kernel/ioservice/1811184-waitquiet.md)
- [willTerminate](kernel/ioservice/1811202-willterminate.md)
- [youAreRoot](kernel/ioservice/1811214-youareroot.md)