iokit/IOKit/IOService.h

1341     @discussion Removes the driver from the power plane and stop its power management. This method is synchronous against any power management method invocations (e.g. <code>setPowerState</code> or <code>setAggressiveness</code>), so when this method returns it is guaranteed those power management methods will not be entered. Driver should not call any power management methods after this call.
1356     @discussion A driver defines its array of supported power states with power management in its power management initialization (its <code>start</code> routine). If successful, power management will call the driver to instruct it to change its power state through @link setPowerState setPowerState@/link.
1401     @abstract Acknowledges the belated completion of a driver's <code>setPowerState</code> power state change.
1402     @discussion After power management instructs a driver to change its state via @link setPowerState setPowerState@/link, that driver must acknowledge the change when its device has completed its transition. The acknowledgement may be immediate, via a return code from <code>setPowerState</code>, or delayed, via this call to <code>acknowledgeSetPowerState</code>.
1403     Any driver that does not return <code>kIOPMAckImplied</code> from its <code>setPowerState</code> implementation must later call <code>acknowledgeSetPowerState</code>.
1597 /*! @function setPowerState
1599     @discussion A power managed driver must override <code>setPowerState</code> to take part in system power management. After a driver is registered with power management, the system uses <code>setPowerState</code> to power the device off and on for system sleep and wake.
1600     Calls to @link PMinit PMinit@/link and @link registerPowerDriver registerPowerDriver@/link enable power management to change a device's power state using <code>setPowerState</code>. <code>setPowerState</code> is called in a clean and separate thread context.
1605     virtual IOReturn setPowerState(