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PO_FX_COMPONENT_IDLE_STATE structure (wdm.h)

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The PO_FX_COMPONENT_IDLE_STATE structure specifies the attributes of an Fx power state of a component in a device.

Syntax

typedef struct _PO_FX_COMPONENT_IDLE_STATE {
  ULONGLONG TransitionLatency;
  ULONGLONG ResidencyRequirement;
  ULONG     NominalPower;
} PO_FX_COMPONENT_IDLE_STATE, *PPO_FX_COMPONENT_IDLE_STATE;

Members

TransitionLatency

The transition latency. This latency is the amount of time, in 100-nanosecond units, that the component requires to return from this Fx state to the F0 state. For a PO_FX_COMPONENT_IDLE_STATE structure that specifies the attributes of the F0 state, set this member to zero.

ResidencyRequirement

The residency requirement. The residency requirement is the minimum amount of time, in 100-nanosecond units, that the component must spend in this Fx state to make a transition to this Fx state worthwhile. PoFx uses this member value as a hint to avoid switching a component to an Fx state unless the component is likely to remain in this state for at least the amount of time specified by ResidencyRequirement. For a PO_FX_COMPONENT_IDLE_STATE structure that describes the attributes of the F0 state, set this member to zero.

NominalPower

The power, in microwatts, that the component consumes in this Fx state. Set this member to PO_FX_UNKNOWN_POWER to indicate that PoFx should ignore (treat as negligible) the component's internal power consumption in this Fx state when PoFx evaluates which power state to switch to when the component is idle.

Remarks

The PO_FX_COMPONENT structure contains a pointer to an array of PO_FX_COMPONENT_IDLE_STATE structures. Each array element specifies the attributes of an Fx state. Element 0 describes F0, element 1 describes F1, and so on.

When the driver registers a device with PoFx, the driver supplies an array of PO_FX_COMPONENT structures. Each array element describes the power attributes of a component in the device.

Do not set TransitionLatency and ResidencyRequirement to PO_FX_UNKNOWN_TIME because it may prevent the power management framework (PoFx) from selecting the idle state.

Requirements

Requirement Value
Minimum supported client Supported starting with Windows 8.
Header wdm.h (include Wudfwdm.h)

See also

PO_FX_COMPONENT