请教usb板与主机通讯的问题，给高分！

各位大侠，请教个问题，我的板子是89c52+d12，大批量向主机传输数据是采用管道2。但传输一段时间后就会出现deviceiocontrol失败的消息，请问是怎么回事情啊，这部分程序如下：UINT ReadPipe(void * pParam)
{
char temp[80];
unsigned int             i;
BOOLEAN bResult = FALSE;
ULONG nBytes = 0;
struct CThreadParam * threadParam;
CXugy03Dlg * testDlg;
HANDLE hFile,hDevice;
DWORD time0, time1;
IO_BLOCK ioBlock;
IO_REQUEST ioRequest;


threadParam = (struct CThreadParam *) pParam;
threadParam->bInThread = FALSE;
testDlg = threadParam->testDlg;
threadParam ->bUpdate = FALSE;

hFile = open_file(threadParam->pipe_name);
if(hFile == INVALID_HANDLE_VALUE)
{
strcpy(temp,\"open_file打开失败 \");
strcat(temp,threadParam->pipe_name);
testDlg->MessageBox(temp, \" ReadPipe err notice:\",MB_OK);
testDlg->m_InStartBtn.EnableWindow(TRUE);
testDlg->m_InStopBtn.EnableWindow(FALSE);
return 0;
}

hDevice = open_dev();
if (hDevice == INVALID_HANDLE_VALUE)
{
CloseHandle(hFile);
strcpy(temp,\"open_dev打开失败 \");
strcat(temp,threadParam->pipe_name);
testDlg->MessageBox(temp, \" ReadPipe err notice:\",MB_OK);
testDlg->m_InStartBtn.EnableWindow(TRUE);
testDlg->m_InStopBtn.EnableWindow(FALSE);
return 0;
}

threadParam->pcIoBuffer = (unsigned char *)
malloc (threadParam->uiLength+16);
if(threadParam->pcIoBuffer == NULL)
{
testDlg->MessageBox(\"内存不够\", \"ReadPipe:\", MB_ICONSTOP);
testDlg->EndDialog(0);
return 0;
}
threadParam->ulCount =0;
threadParam->total_time = 0;
threadParam->max_rate = 0;
threadParam->cur_rate = 0;



if(hFile != INVALID_HANDLE_VALUE)
{
threadParam->bInThread = TRUE;
do
{
Sleep(7);   //10:163k; 5:202k; 6:226k;7:241
ioRequest.uAddressL = 0;
ioRequest.bAddressH = 0;
ioRequest.uSize = threadParam->uiLength;
ioRequest.bCommand = 0x81; //start read

ioBlock.uOffset = 0;
ioBlock.uLength = sizeof(IO_REQUEST);
ioBlock.pbyData = (PUCHAR)&ioRequest;
ioBlock.uIndex = SETUP_DMA_REQUEST;
      
bResult = DeviceIoControl(hDevice,
IOCTL_WRITE_REGISTERS,
(PVOID)&ioBlock,
sizeof(IO_BLOCK),
NULL,
0,
&nBytes,
NULL);

if(!bResult)
{
threadParam->bInThread = FALSE;
strcpy(temp,\"DeviceIoControl 失败 \");
strcat(temp,threadParam->pipe_name);
testDlg->MessageBox(temp, \" ReadPipe err notice:\",MB_OK);
break;
}

time0 = timeGetTime();
bResult = ReadFile(hFile,
threadParam->pcIoBuffer,
threadParam->uiLength,
&nBytes,
NULL);
// threadParam->ulCount +=nBytes;
time1 = timeGetTime();
if(!bResult)      
{
DeviceIoControl(hFile,
IOCTL_D12_RESET_PIPE,
0, 0, 0, 0,
&nBytes,
NULL);
threadParam->bInThread = FALSE;
strcpy(temp,\"ReadFile失败 \");
strcat(temp,threadParam->pipe_name);
testDlg->MessageBox(temp, \" ReadPipe err notice:\",MB_OK);
break;
}
else
{  
for(i=0;i<threadParam->uiLength;i++)
threadParam->ulData=* (threadParam->pcIoBuffer+i);

threadParam->ulCount+=nBytes;
if (time0!=time1)
{

threadParam->cur_rate = (nBytes*1000)/(time1-time0);
if(threadParam->cur_rate > threadParam->max_rate)
{
threadParam->max_rate = threadParam->cur_rate;
}
threadParam->total_time += (time1 - time0 );
threadParam->bUpdate = TRUE;
}
else
{
    if (nBytes>0)
{
threadParam->cur_rate = (nBytes*1000)/1;
if(threadParam->cur_rate > threadParam->max_rate)
{
threadParam->max_rate = threadParam->cur_rate;
}
threadParam->total_time += (time1-time0);
threadParam->bUpdate = TRUE;
//            time2 = timeGetTime();
}    
}
}//end if(!bRequest),else

} while(threadParam->bInThread == TRUE);

} //end if(hFile != INVALID_HANDLE_VALUE)


CloseHandle(hFile);
CloseHandle(hDevice);
free(threadParam->pcIoBuffer);
threadParam->pcIoBuffer = NULL;
threadParam->bInThread = FALSE;
testDlg->m_InStartBtn.EnableWindow(TRUE);
testDlg->m_InStopBtn.EnableWindow(FALSE);

return 0;
}

Please modify USB firmware and set host\'s process/thread priority higher.