MDL version of sending routine

    //Create request
    if (context->request == NULL)
    {
        ntStatus = WdfRequestCreate(&objectAttributes, NULL, &context->request);
        if (!NT_SUCCESS(ntStatus))
        {
            DbgPrint("WdfRequestCreate failed: %x\n", ntStatus);
            return;
        }
    }
    else
    {
        //Reuse request
        WDF_REQUEST_REUSE_PARAMS  paramsR;
        WDF_REQUEST_REUSE_PARAMS_INIT(&paramsR, WDF_REQUEST_REUSE_NO_FLAGS, STATUS_SUCCESS);

        ntStatus = WdfRequestReuse(context->request, &paramsR);
        if (!NT_SUCCESS(ntStatus))
            DbgPrint("sendAudioData: WdfRequestReuse failed: %x\n", ntStatus);
        ASSERT(NT_SUCCESS(ntStatus));
    }

    //Create URB structure
    if (context->urbMemory == NULL)
    {
        WDF_OBJECT_ATTRIBUTES_INIT(&objectAttributes);
        objectAttributes.ParentObject = usbDevice;
        ntStatus = WdfUsbTargetDeviceCreateIsochUrb(usbDevice, &objectAttributes, MAX_PAKETS, &context->urbMemory, NULL);
        if (!NT_SUCCESS(ntStatus))
        {
            DbgPrint("sendAudioData: WdfTargetDeviceCreateIsochUrb failed: %x\n", ntStatus);
            return;
        }
    }

    //Create outputBuffer
    ULONG bufferLen = numPackets * numOfSamplesPerPacket * getAudioBufferForChannel(channel)->getSampleSize();
    if (context->dataBuffer == NULL)
    {
        AudioBuffer* buffer = getAudioBufferForChannel(channel);
        PHYSICAL_ADDRESS low;
        RtlZeroMemory(&low, sizeof(PHYSICAL_ADDRESS));
        PHYSICAL_ADDRESS high;
        high.QuadPart = _UI64_MAX;
        PHYSICAL_ADDRESS skip;
        skip.QuadPart = PAGE_SIZE;
        context->dataBuffer = MmAllocatePagesForMdlEx(low, high, skip, buffer->getSampleSize()*buffer->getSize(), MmCached, MM_ALLOCATE_PREFER_CONTIGUOUS);
    }

    PURB urb = (PURB)WdfMemoryGetBuffer(context->urbMemory, NULL);

    urb->UrbIsochronousTransfer.Hdr.Length = GET_ISO_URB_SIZE(numPackets);
    urb->UrbIsochronousTransfer.Hdr.Function = URB_FUNCTION_ISOCH_TRANSFER;
    urb->UrbIsochronousTransfer.PipeHandle = WdfUsbTargetPipeWdmGetPipeHandle(channelEndpoints[channel].dataPipe);
    urb->UrbIsochronousTransfer.TransferFlags = USBD_TRANSFER_DIRECTION_OUT | USBD_START_ISO_TRANSFER_ASAP;
    urb->UrbIsochronousTransfer.TransferBufferLength = bufferLen;
    urb->UrbIsochronousTransfer.NumberOfPackets = numPackets;
    urb->UrbIsochronousTransfer.TransferBufferMDL = context->dataBuffer;
    for (ULONG i = 0; i != numPackets; i++)
        urb->UrbIsochronousTransfer.IsoPacket[i].Offset = i * numOfSamplesPerPacket * getAudioBufferForChannel(channel)->getSampleSize();

    //Copy audio data into buffer
    AudioBuffer* buffer = getAudioBufferForChannel(channel);
    //ToDo: Temporary - in final release shoud be removed - add dummy samples
    buffer->fillBufferWithSine(currentFrequency);
    //I've tried both possibilities - both with the same result
    //BYTE* ioBuff = (BYTE*)MmGetMdlVirtualAddress(context->dataBuffer);
    BYTE* ioBuff = (BYTE*)MmGetSystemAddressForMdlSafe(context->dataBuffer, HighPagePriority);

    //Following 2 lines couses probelm
    memset(ioBuff, 0, bufferLen);
    buffer->popSamples(ioBuff, numOfSamplesPerPacket * numPackets);


    ntStatus = WdfUsbTargetPipeFormatRequestForUrb(channelEndpoints[channel].dataPipe, context->request, context->urbMemory, 0);
    if (!NT_SUCCESS(ntStatus))
    {
        DbgPrint("WdfUsbTargetDeviceFormatRequestForUrb failed: %x\n", ntStatus);
        return;
    }

    SendContext* sContext = &channelEndpoints[channel].sendSpecificContext;
    sContext->device = this;
    sContext->channel = channel;
    WdfRequestSetCompletionRoutine(context->request, sendRequestComplete, sContext);

    if (WdfRequestSend(context->request, WdfUsbTargetPipeGetIoTarget(channelEndpoints[channel].dataPipe), WDF_NO_SEND_OPTIONS) == FALSE)
    {
        ntStatus = WdfRequestGetStatus(context->request);
        DbgPrint("WdfRequestSend failed with status code 0x%x\n", ntStatus);
    }