Requirements for WDM (non-miniport) drivers To do so, provide an WDF_DEVICE_POWER_POLICY_IDLE_SETTINGS structure as input to WdfDeviceAssignS0IdleSettings. If the WDF driver does not use runtime power management, add support for it and use system-managed idle timeout. If that is not feasible, use the guidelines in the WDM section below to opt into DFx. If the driver specifies DriverManagedIdleTimeout, consider switching to system-managed idle timeout. To initialize its WDF_POWER_FRAMEWORK_SETTINGS structure, your driver should call WDF_POWER_FRAMEWORK_SETTINGS_INIT.īecause requesting system-managed idle timeout causes WDF to register with PoFx on the driver's behalf, the driver does not need to register with PoFx in this scenario.
HKR,"WDF","WdfDirectedPowerTransitionEnable",0x00010001,0Ī WDF driver targeting version 33 and above can alternatively opt out of DFx by setting the DirectedPoF圎nabled member of the WDF_POWER_FRAMEWORK_SETTINGS structure to WdfFalse. If this is undesired, the driver can opt out of DFx by setting the registry key to 0: HKR,"WDF","WdfDirectedPowerTransitionEnable",0x00010001,1Ī WDF driver targeting version 31 and above will enable DFx by default.
Requirements for WDF (non-miniport) driversĪ WDF driver that specifies SystemManagedIdleTimeout or SystemManagedIdleTimeoutWithHint in the WDF_DEVICE_POWER_POLICY_IDLE_SETTINGS structure can opt into DFx by adding the following registry key to the INF's AddReg directive section within the DDInstall.HW section: DFx skips any device subtree with an F-state constraint.ĭFx does not power down paging or debug devices. The objective is to make systems more power-efficient and to reduce energy consumption for Windows devices across form factors.ĭFx is currently supported for devices with D-state constraints only. With DFx, the operating system directs device stacks to enter their appropriate low-power idle states when the system transitions to idle and there is no activator-brokered software activity, and thereby enables the system to enter low power more reliably. Starting in Windows 10, version 1903, version 3 of the run-time power management framework ( PoFx) provides an optional directed power model, Directed PoFx (DFx). Introduction to the Directed Power Management Framework
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