PoSetPowerState function (ntifs.h)

The PoSetPowerState routine notifies the system of a change in the device power state for a device.

Syntax

POWER_STATE PoSetPowerState(
  [in] PDEVICE_OBJECT   DeviceObject,
  [in] POWER_STATE_TYPE Type,
  [in] POWER_STATE      State
);

Parameters

[in] DeviceObject

A pointer to the target DEVICE_OBJECT.

[in] Type

Indicates a POWER_STATE_TYPE value. Drivers must specify DevicePowerState.

[in] State

Specifies the power state to be set. Drivers must specify a DEVICE_POWER_STATE value.

Return value

PoSetPowerState returns the previous power state.

Remarks

PoSetPowerState notifies the power manager of the new power state for a device. Each driver in a device stack (filter, function, and bus drivers) must call PoSetPowerState to inform the power manager of a change in the power state of its corresponding device object. For example:

• A driver calls this routine after receiving a device set-power request and before calling PoStartNextPowerIrp. When handling a PnP IRP_MN_START_DEVICE request, the driver should call PoSetPowerState to notify the power manager that the device is in the D0 state.

• If the device is powering down, the driver must call PoSetPowerState before leaving the D0 state. In addition, the driver must be able to process client requests before PoSetPowerState returns.

• If the device is powering up, the driver must call PoSetPowerState after the device is successfully put into the D0 state.

For more information about powering a device up and down, see Handling IRP_MN_SET_POWER for Device Power States.

Callers of PoSetPowerState must be running at IRQL <= APC_LEVEL except when setting state to D0. When setting state to D0, callers can be running at IRQL <= DISPATCH_LEVEL.

Requirements

See also

IRP_MN_START_DEVICE

PoStartNextPowerIrp