PoSetPowerState(DeviceObject, DevicePowerState, newState);
    }

    PoStartNextPowerIrp(Irp);

    BulkUsb_DbgPrint(3, ("FinishDevPoDnIrp::"));
    BulkUsb_IoDecrement(DeviceExtension);

    BulkUsb_DbgPrint(3, ("FinishDevPoDnIrp - ends\n"));

    return STATUS_SUCCESS;
}

NTSTATUS
HoldIoRequests(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP           Irp
    )
/*++
 
Routine Description:

    This routine is called on query or set power DOWN irp for the device.
    This routine queues a workitem.

Arguments:

    DeviceObject - pointer to device object
    Irp - I/O request packet

Return Value:

    NT status value

--*/
{
    NTSTATUS               ntStatus;
    PIO_WORKITEM           item;
    PDEVICE_EXTENSION      deviceExtension;
    PWORKER_THREAD_CONTEXT context;

    //
    // initialize variables
    //
    deviceExtension = (PDEVICE_EXTENSION) DeviceObject->DeviceExtension;

    BulkUsb_DbgPrint(3, ("HoldIoRequests - begins\n"));

    deviceExtension->QueueState = HoldRequests;

    context = ExAllocatePool(NonPagedPool, sizeof(WORKER_THREAD_CONTEXT));

    if(context) {

        item = IoAllocateWorkItem(DeviceObject);

        context->Irp = Irp;
        context->DeviceObject = DeviceObject;
        context->WorkItem = item;

        if(item) {

            IoMarkIrpPending(Irp);
            
            IoQueueWorkItem(item, HoldIoRequestsWorkerRoutine,
                            DelayedWorkQueue, context);
            
            ntStatus = STATUS_PENDING;
        }
        else {

            BulkUsb_DbgPrint(3, ("Failed to allocate memory for workitem\n"));
            ExFreePool(context);
            ntStatus = STATUS_INSUFFICIENT_RESOURCES;
        }
    }
    else {

        BulkUsb_DbgPrint(1, ("Failed to alloc memory for worker thread context\n"));
        ntStatus = STATUS_INSUFFICIENT_RESOURCES;
    }

    BulkUsb_DbgPrint(3, ("HoldIoRequests - ends\n"));

    return ntStatus;
}

VOID
HoldIoRequestsWorkerRoutine(
    IN PDEVICE_OBJECT DeviceObject,
    IN PVOID          Context
    )
/*++
 
Routine Description:

    This routine waits for the I/O in progress to finish and then
    sends the device power irp (query/set) down the stack.

Arguments:

    DeviceObject - pointer to device object
    Context - context passed to the work-item.

Return Value:

    None

--*/
{
    PIRP                   irp;
    NTSTATUS               ntStatus;
    PDEVICE_EXTENSION      deviceExtension;
    PWORKER_THREAD_CONTEXT context;

    BulkUsb_DbgPrint(3, ("HoldIoRequestsWorkerRoutine - begins\n"));

    //
    // initialize variables
    //
    deviceExtension = (PDEVICE_EXTENSION) DeviceObject->DeviceExtension;
    context = (PWORKER_THREAD_CONTEXT) Context;
    irp = (PIRP) context->Irp;


    //
    // wait for I/O in progress to finish.
    // the stop event is signalled when the counter drops to 1.
    // invoke BulkUsb_IoDecrement twice: once each for the S-Irp and D-Irp.
    //
    BulkUsb_DbgPrint(3, ("HoldIoRequestsWorkerRoutine::"));
    BulkUsb_IoDecrement(deviceExtension);
    BulkUsb_DbgPrint(3, ("HoldIoRequestsWorkerRoutine::"));
    BulkUsb_IoDecrement(deviceExtension);

    KeWaitForSingleObject(&deviceExtension->StopEvent, Executive,
                          KernelMode, FALSE, NULL);

    //
    // Increment twice to restore the count
    //
    BulkUsb_DbgPrint(3, ("HoldIoRequestsWorkerRoutine::"));
    BulkUsb_IoIncrement(deviceExtension);
    BulkUsb_DbgPrint(3, ("HoldIoRequestsWorkerRoutine::"));
    BulkUsb_IoIncrement(deviceExtension);

    // 
    // now send the Irp down
    //

    IoCopyCurrentIrpStackLocationToNext(irp);

    IoSetCompletionRoutine(irp, (PIO_COMPLETION_ROUTINE) FinishDevPoDnIrp,
                           deviceExtension, TRUE, TRUE, TRUE);

    ntStatus = PoCallDriver(deviceExtension->TopOfStackDeviceObject, irp);

    if(!NT_SUCCESS(ntStatus)) {

        BulkUsb_DbgPrint(1, ("Lower driver fail a power Irp\n"));
    }

    IoFreeWorkItem(context->WorkItem);
    ExFreePool((PVOID)context);

    BulkUsb_DbgPrint(3, ("HoldIoRequestsWorkerRoutine - ends\n"));

}

NTSTATUS
QueueRequest(
    IN OUT PDEVICE_EXTENSION DeviceExtension,
    IN PIRP Irp
    )
/*++
 
Routine Description:

    Queue the Irp in the device queue

Arguments:

    DeviceExtension - pointer to device extension
    Irp - I/O request packet.

Return Value:

    NT status value

--*/
{
    KIRQL    oldIrql;
    NTSTATUS ntStatus;

    //
    // initialize variables
    //
    ntStatus = STATUS_PENDING;

    BulkUsb_DbgPrint(3, ("QueueRequests - begins\n"));

    ASSERT(HoldRequests == DeviceExtension->QueueState);

    KeAcquireSpinLock(&DeviceExtension->QueueLock, &oldIrql);

    InsertTailList(&DeviceExtension->NewRequestsQueue, 
                   &Irp->Tail.Overlay.ListEntry);

    IoMarkIrpPending(Irp);

    //
    // Set the cancel routine
    //

    IoSetCancelRoutine(Irp, CancelQueued);

    KeReleaseSpinLock(&DeviceExtension->QueueLock, oldIrql);

    BulkUsb_DbgPrint(3, ("QueueRequests - ends\n"));

    return ntStatus;
}

VOID
CancelQueued(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP           Irp
    )
/*++
 
Routine Description:

    This routine removes the irp from the queue and completes it with
    STATUS_CANCELLED

Arguments:

    DeviceObject - pointer to device object
    Irp - I/O request packet

Return Value:

    None.

--*/
{
    PDEVICE_EXTENSION deviceExtension;
    KIRQL             oldIrql;

    //
    // initialize variables
    //
    deviceExtension = (PDEVICE_EXTENSION) DeviceObject->DeviceExtension;
    oldIrql = Irp->CancelIrql;

    BulkUsb_DbgPrint(3, ("CancelQueued - begins\n"));

    //
    // Release the cancel spin lock
    //

    IoReleaseCancelSpinLock(Irp->CancelIrql);

    //
    // Acquire the queue lock
    //

    KeAcquireSpinLockAtDpcLevel(&deviceExtension->QueueLock);

    //
    // Remove the cancelled Irp from queue and release the lock
    //
    RemoveEntryList(&Irp->Tail.Overlay.ListEntry);

    KeReleaseSpinLock(&deviceExtension->QueueLock, oldIrql);

    //
    // complete with STATUS_CANCELLED
    //

    Irp->IoStatus.Status = STATUS_CANCELLED;
    Irp->IoStatus.Information = 0;
    IoCompleteRequest(Irp, IO_NO_INCREMENT);

    BulkUsb_DbgPrint(3, ("CancelQueued - ends\n"));

    return;
}

NTSTATUS
IssueWaitWake(
    IN PDEVICE_EXTENSION DeviceExtension
    )
/*++
 
Routine Description:

    This routine will PoRequest a WAIT WAKE irp for the device

Arguments:

    DeviceExtension - pointer to device extension

Return Value:

    NT status value.

--*/
{
    POWER_STATE poState;
    NTSTATUS    ntStatus;

    BulkUsb_DbgPrint(3, ("IssueWaitWake - begins\n"));

    if(InterlockedExchange(&DeviceExtension->FlagWWOutstanding, 1)) {

        return STATUS_DEVICE_BUSY;
    }

    InterlockedExchange(&DeviceExtension->FlagWWCancel, 0);

    //
    // lowest state from which this Irp will wake the system
    //

    poState.SystemState = DeviceExtension->DeviceCapabilities.SystemWake;

    ntStatus = PoRequestPowerIrp(DeviceExtension->PhysicalDeviceObject, 
                                 IRP_MN_WAIT_WAKE,
                                 poState, 
                                 (PREQUEST_POWER_COMPLETE) WaitWakeCallback,
                                 DeviceExtension, 
                                 &DeviceExtension->WaitWakeIrp);

    if(!NT_SUCCESS(ntStatus)) {

        InterlockedExchange(&DeviceExtension->FlagWWOutstanding, 0);
    }

    BulkUsb_DbgPrint(3, ("IssueWaitWake - ends\n"));

    return ntStatus;
}

VOID
CancelWaitWake(
    IN PDEVICE_EXTENSION DeviceExtension
    )
/*++
 
Routine Description:

    This routine cancels the Wait Wake request.

Arguments:

    DeviceExtension - pointer to the device extension

Return Value:

    None.

--*/
{
    PIRP Irp;

    BulkUsb_DbgPrint(3, ("CancelWaitWake - begins\n"));

    Irp = (PIRP) InterlockedExchangePointer(&DeviceExtension->WaitWakeIrp, 
                                            NULL);

    if(Irp) {

        IoCancelIrp(Irp);

        if(InterlockedExchange(&DeviceExtension->FlagWWCancel, 1)) {

            PoStartNextPowerIrp(Irp);

            Irp->IoStatus.Status = STATUS_CANCELLED;
            Irp->IoStatus.Information = 0;

            IoCompleteRequest(Irp, IO_NO_INCREMENT);
        }    
    }

    BulkUsb_DbgPrint(3, ("CancelWaitWake - ends\n"));
}

NTSTATUS
WaitWakeCompletionRoutine(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PDEVICE_EXTENSION DeviceExtension
    )
/*++
 
Routine Description:

    This is the IoSet completion routine for the wait wake irp.

Arguments:

    DeviceObject - pointer to device object
    Irp - I/O request packet
    DeviceExtension - pointer to device extension

Return Value:

    NT status value

--*/
{
    BulkUsb_DbgPrint(3, ("WaitWakeCompletionRoutine - begins\n"));

    if(Irp->PendingReturned) {

        IoMarkIrpPending(Irp);
    }

    //
    // Nullify the WaitWakeIrp pointer-the Irp is released 
    // as part of the completion process. If it's already NULL, 
    // avoid race with the CancelWaitWake routine.
    //

    if(InterlockedExchangePointer(&DeviceExtension->WaitWakeIrp, NULL)) {

        PoStartNextPowerIrp(Irp);

        return STATUS_SUCCESS;
    }

    //
    // CancelWaitWake has run. 
    // If FlagWWCancel != 0, complete the Irp.
    // If FlagWWCancel == 0, CancelWaitWake completes it.
    //
    if(InterlockedExchange(&DeviceExtension->FlagWWCancel, 1)) {

        PoStartNextPowerIrp(Irp);

        return STATUS_CANCELLED;
    }

    BulkUsb_DbgPrint(3, ("WaitWakeCompletionRoutine - ends\n"));

    return STATUS_MORE_PROCESSING_REQUIRED;
}

VOID
WaitWakeCallback( 
    IN PDEVICE_OBJECT DeviceObject,
    IN UCHAR MinorFunction,
    IN POWER_STATE PowerState,
    IN PVOID Context,
    IN PIO_STATUS_BLOCK IoStatus
    )
/*++
 
Routine Description:

    This is the PoRequest completion routine for the wait wake irp.

Arguments:

    DeviceObject - pointer to device object
    MinorFunction - irp minor function
    PowerState - power state of the irp.
    Context - context passed to the completion routine.
    IoStatus - status block.

Return Value:

    None

--*/
{
    NTSTATUS               ntStatus;
    POWER_STATE            powerState;
    PDEVICE_EXTENSION      deviceExtension;

    BulkUsb_DbgPrint(3, ("WaitWakeCallback - begins\n"));

    deviceExtension = (PDEVICE_EXTENSION) Context;

    InterlockedExchange(&deviceExtension->FlagWWOutstanding, 0);

    if(!NT_SUCCESS(IoStatus->Status)) {

        return;
    }

    //
    // wake up the device
    //

    if(deviceExtension->DevPower == PowerDeviceD0) {

        BulkUsb_DbgPrint(3, ("device already powered up...\n"));

        return;
    }

    BulkUsb_DbgPrint(3, ("WaitWakeCallback::"));
    BulkUsb_IoIncrement(deviceExtension);

    powerState.DeviceState = PowerDeviceD0;

    ntStatus = PoRequestPowerIrp(deviceExtension->PhysicalDeviceObject, 
                                 IRP_MN_SET_POWER, 
                                 powerState, 
                                 (PREQUEST_POWER_COMPLETE) WWIrpCompletionFunc,
                                 deviceExtension, 
                                 NULL);

    if(deviceExtension->WaitWakeEnable) {

        IssueWaitWake(deviceExtension);
    }

    BulkUsb_DbgPrint(3, ("WaitWakeCallback - ends\n"));

    return;
}


PCHAR
PowerMinorFunctionString (
    IN UCHAR MinorFunction
    )
/*++
 
Routine Description:

Arguments:

Return Value:

--*/
{
    switch (MinorFunction) {

        case IRP_MN_SET_POWER:
            return "IRP_MN_SET_POWER\n";

        case IRP_MN_QUERY_POWER:
            return "IRP_MN_QUERY_POWER\n";

        case IRP_MN_POWER_SEQUENCE:
            return "IRP_MN_POWER_SEQUENCE\n";

        case IRP_MN_WAIT_WAKE:
            return "IRP_MN_WAIT_WAKE\n";

        default:
            return "IRP_MN_?????\n";
    }
}