UfxDeviceNotifyAttach function (ufxclient.h)

Article
09/19/2022

Notifies UFX that the device's USB cable has been attached.

Syntax

void UfxDeviceNotifyAttach(
  [in] UFXDEVICE UfxDevice
);

Parameters

[in] UfxDevice

A handle to a UFX device object that the driver created by calling UfxDeviceCreate.

Return value

None

Remarks

When the client driver calls UfxDeviceNotifyAttach, the USB function class extension (UFX) does the following:

Moves the device to the powered state, as defined in the USB specification.
Allows device enumeration to occur.

The client driver typically calls UfxDeviceNotifyAttach from its EVT_WDF_INTERRUPT_DPC callback function, as shown in the following example.

VOID 
DeviceInterrupt_EvtInterruptDpc (
    _In_ WDFINTERRUPT Interrupt,
    _In_ WDFOBJECT AssociatedObject
    )
/*++

Routine Description:

    'EVT_WDF_INTERRUPT_DPC' handler for the device interrupt object.

Arguments:

    Interrupt - Associated interrupt object.

    AssociatedObject - FDO Object

--*/
{
    WDFDEVICE WdfDevice;
    PDEVICE_INTERRUPT_CONTEXT InterruptContext;
    PCONTROLLER_CONTEXT ControllerContext;
    BOOLEAN Attached;
    BOOLEAN GotAttachOrDetach;
    CONTROLLER_EVENT ControllerEvent;

    UNREFERENCED_PARAMETER(Interrupt);

    TraceEntry();

    WdfDevice = (WDFDEVICE) AssociatedObject;
    ControllerContext = DeviceGetControllerContext(WdfDevice);

    WdfSpinLockAcquire(ControllerContext->DpcLock);

    WdfInterruptAcquireLock(ControllerContext->DeviceInterrupt);
    Attached = ControllerContext->Attached;
    GotAttachOrDetach = ControllerContext->GotAttachOrDetach;
    ControllerContext->GotAttachOrDetach = FALSE;
    WdfInterruptReleaseLock(ControllerContext->DeviceInterrupt);

    //
    // Handle attach/detach events
    //
    if (GotAttachOrDetach) {
        if (Attached && ControllerContext->WasAttached) {
            //
            // We must have gotten at least one detach. Need to reset the state.
            //        
            ControllerContext->RemoteWakeupRequested = FALSE;
            ControllerContext->Suspended = FALSE;
            UfxDeviceNotifyDetach(ControllerContext->UfxDevice);
        }

        if (Attached) {
            ControllerContext->RemoteWakeupRequested = FALSE;
            ControllerContext->Suspended = FALSE;
            UfxDeviceNotifyAttach(ControllerContext->UfxDevice);
        }
    }

    ControllerContext->WasAttached = Attached;

    InterruptContext = DeviceInterruptGetContext(ControllerContext->DeviceInterrupt);

    //
    // #### TODO: Insert code to read and dispatch events from the controller ####
    // 

    // The sample will assume an endpoint event of EndpointEventTransferComplete
    ControllerEvent.Type = EventTypeEndpoint;
    ControllerEvent.u.EndpointEvent = EndpointEventTransferComplete;
    
    //
    // Handle events from the controller
    //
    switch (ControllerEvent.Type) {
    case EventTypeDevice:
        HandleDeviceEvent(WdfDevice, ControllerEvent.u.DeviceEvent);
        break;

    case EventTypeEndpoint:
        HandleEndpointEvent(WdfDevice, ControllerEvent.u.EndpointEvent);
        break;
    }

    WdfSpinLockRelease(ControllerContext->DpcLock);

    TraceExit();
}

Requirements

Requirement	Value
Minimum supported client	Windows 10
Target Platform	Windows
Header	ufxclient.h
Library	ufxstub.lib
IRQL	DISPATCH_LEVEL

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