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4/8/2010

This enumeration describes the device power states. The PwrDeviceUnspecifiedand PwrDeviceMaximumvalues are not valid device power states but are used for some Power Manager functions.

Syntax 

typedef enum _CEDEVICE_POWER_STATE {
  PwrDeviceUnspecified = -1,
  D0 = 0,
  D1,
  D2,
  D3,
  D4,
  PwrDeviceMaximum
} CEDEVICE_POWER_STATE, *PCEDEVICE_POWER_STATE;

Elements

PwrDeviceUnspecified

System state is unspecified.

D0

Full On. This is the state in which the device is on and running. It is receiving full power from the system and is delivering full functionality to the user.

D1

Low On. This is the state in which the device is fully functional at a lower power state than D0, a lower performance state than D0, or both. This state is applicable when the device is being used, but where peak performance is unnecessary and power is at a premium.

D2

Standby. This is the state in which the device is partially powered with automatic wakeup on request. The device is effectively standing by.

D3

Sleep. This is the state in which the device is partially powered with device-initiated wakeup if available. A device in state D3 is sleeping but capable of raising the system power state on its own. It consumes only enough power to be able to do so; which must be less than or equal to the amount of power used in state D2.

D4

Off. This is the state in which the device is not powered. A device in state D4 should not be consuming any significant power. Some peripheral busses require static terminations that intrinsically use non-zero power when a device is physically connected to the bus; a device on such a bus can still support D4.

PwrDeviceMaximum

Valid device power state values are greater than PwrDeviceUnspecifiedand less than PwrDeviceMaximum.

See Also