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4/8/2010

This structure is used for drivers to report the power management capabilities of a device.

Syntax 

typedef struct _POWER_CAPABILITIES {
  UCHAR 
DeviceDx;
  UCHAR 
WakeFromDx;
  UCHAR 
InrushDx;
  DWORD 
Power[5];
  DWORD 
Latency[5];
  DWORD 
Flags;
} POWER_CAPABILITIES, *PPOWER_CAPABILITIES;

Members

DeviceDx

Bit mask that indicates whether the device hardware supports these device states. Each is a single bit, set if the device supports the state, and clear if the device does not support the state.

WakeFromDx

Bit mask that indicates whether the device hardware can awaken in response to an external signal that arrives when the device is in the specified state. Each is a single bit, set if the device supports wake from the state, and clear if the device does not support wake from the state.

InrushDx

Bit mask that indicates whether the device hardware has inrush requirements at the specified device state. Each is a single bit, set if the device has inrush requirements at the state, and clear if the device does not. Drivers for devices that require an inrush of power at the specified state must set the appropriate bits. Bus drivers may need to set Inrush. The flag notifies Power Manager that such devices must be powered up one at a time, in sequence with other such devices.

Inrush is a sudden rushing in of power.

Power

This is an array of five values, indexed by the CEDEVICE_POWER_STATEvalues ranging from D0 to D4. Each element of the array contains the maximum or highest-power usage, in milliwatts, that the device uses for the device power state denoted by the array index, or PwrDeviceUnspecifiedif the system state is not supported. Devices with their own power supplies, even if it is a self-contained battery, should only report their drains on the system power supply.

Latency

Contains an array of the approximate time, in milliseconds, that the device requires to return to the D0 state from each of the specified states. A driver should specify a latency time of PwrDeviceUnspecifiedfor any device state it does not support.

Flags

Set to POWER_CAP_PARENT bit if the device should receive an IOCTL_REGISTER_POWER_RELATIONSHIP call after initialization.

Remarks

During enumeration, drivers report device-specific information in response to an IOCTL_POWER_CAPABILITIESquery request.

See Also