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4/8/2010

This I/O control checks whether changing power state is feasible. This I/O control is deprecated and is not called by Power Manager.

Parameters

pBufIn

[in] Set to a pointer to POWER_RELATIONSHIP. This defines the target device for parent and bus drivers. Otherwise, set to NULL.

dwLenIn

[in] Size of the POWER_RELATIONSHIPstructure.

pBufOut

[in] Set to a pointer to CEDEVICE_POWER_STATE. This is the device power state that the system is querying for a pending IOCTL_POWER_SEToperation.

[out] Optional. Set to PwrDeviceUnspecifiedto veto the query.

dwLenOut

[out] Size of the CEDEVICE_POWER_STATEparameter.

pdwActualOut

[out] Number of bytes passed back in the pBufOutbuffer.

Return Values

TRUE indicates success. FALSE indicates failure.

Remarks

To veto the query, the driver should write PwrDeviceUnspecifiedinto pBufOut. Otherwise, Power Manager assumes that the driver accepted.

Power Manager sends this I/O control only to drivers that support the power management I/O controls.

This is not always sent before a state transition.

The default implementation of Power Manager does not use IOCTL_POWER_QUERY. OEMs can customize Power Manager to call IOCTL_POWER_QUERYand to honor the return value associated with it so that the code supporting IOCTL_POWER_QUERYis still in the model device driver (MDD).

Requirements

Header pm.h
Windows Embedded CE Windows CE .NET 4.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also