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EvtDeviceWdmPrePoFxUnregisterDevice function

[Applies to KMDF only]

The EvtDeviceWdmPrePoFxUnregisterDevice callback function performs device-specific operations before the framework deletes a specified registration with the power framework.

Syntax


EVT_WDFDEVICE_WDM_PRE_PO_FX_UNREGISTER_DEVICE EvtDeviceWdmPrePoFxUnregisterDevice;

void EvtDeviceWdmPrePoFxUnregisterDevice(
  _In_  WDFDEVICE Device,
  _In_  POHANDLE PoHandle
)
{ ... }

Parameters

Device [in]

A handle to a framework device object.

PoHandle [in]

A handle that represents the device’s registration with the power framework.

Return value

This function does not return a value.

Remarks

The EvtDeviceWdmPrePoFxUnregisterDevice callback function applies only to single-component devices.

To register an EvtDeviceWdmPrePoFxUnregisterDevice callback function, a driver must call WdfDeviceWdmAssignPowerFrameworkSettings.

A driver can provide this callback function if it must perform any additional operations before the framework unregisters the specified POHANDLE.

After the driver has returned from this callback, it is no longer safe to use this POHANDLE.

Examples

To define an EvtDeviceWdmPrePoFxUnregisterDevice callback function, you must first provide a function declaration that identifies the type of callback function you’re defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it’s a requirement for writing drivers for the Windows operating system.

For example, to define an EvtDeviceWdmPrePoFxUnregisterDevice callback function that is named MyDeviceWdmPrePoFxUnregisterDevice, use the EVT_WDFDEVICE_WDM_PRE_PO_FX_UNREGISTER_DEVICE type as shown in this code example:


EVT_WDFDEVICE_WDM_PRE_PO_FX_UNREGISTER_DEVICE  MyDeviceWdmPrePoFxUnregisterDevice;

Then, implement your callback function as follows.


_Use_decl_annotations_
VOID
 MyDeviceWdmPrePoFxUnregisterDevice (
   WDFDEVICE Device,
   POHANDLE PoHandle
   );
  {...}

The EVT_WDFDEVICE_WDM_PRE_PO_FX_UNREGISTER_DEVICE function type is defined in the Wdfdevice.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the EVT_WDFDEVICE_WDM_PRE_PO_FX_UNREGISTER_DEVICE function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.

Requirements

Minimum KMDF version

1.11

Header

Wdfdevice.h (include Wdf.h)

IRQL

PASSIVE_LEVEL

See also

WdfDeviceWdmAssignPowerFrameworkSettings
EvtDeviceWdmPostPoFxRegisterDevice

 

 

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