---
title: changePowerStateToPriv
framework: kernel
role: pseudoSymbol
path: kernel/ioservice/1809819-changepowerstatetopriv
---

# changePowerStateToPriv

Tells a driver's superclass to change the power state of its device.

## Declaration

```occ
IOReturn changePowerStateToPriv(
 unsigned longordinal ); 
```

## Parameters

- `ordinal`: The number of the desired power state in the power state array.

## Return Value

Return Value A return code that can be ignored by the caller.

## Overview

Overview A driver uses this method to tell its superclass to change the power state of the device. This is the recommended way to change the power state of a device. Three things affect driver power state: changePowerStateTo, changePowerStateToPriv, and the desires of the driver's power plane children. Power management puts the device into the maximum state governed by those three entities. Drivers may eliminate the influence of the changePowerStateTo method on power state one of two ways. See powerOverrideOnPriv to ignore the method's influence, or call changePowerStateTo(0) in the driver's start routine to remove the changePowerStateTo method's power request.

## See Also

### Miscellaneous

- [acknowledgePowerChange](kernel/ioservice/1809710-acknowledgepowerchange.md)
- [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)
- [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)