STM32 USB OTG HOST Library hangs trying to create file with FatFs

Question

I am trying to create a file with FatFs on USB flash, but my f_open call trying to read boot sector for first time file system mount hangs on this function.

DRESULT disk_read (
                   BYTE drv,            /* Physical drive number (0) */
                   BYTE *buff,          /* Pointer to the data buffer to store read data */
                   DWORD sector,        /* Start sector number (LBA) */
                   BYTE count           /* Sector count (1..255) */
                     )
{
  BYTE status = USBH_MSC_OK;
  
  if (drv || !count) return RES_PARERR;
  if (Stat & STA_NOINIT) return RES_NOTRDY;
  
  
  if(HCD_IsDeviceConnected(&USB_OTG_Core))
  {  
    
    do
    {
      status = USBH_MSC_Read10(&USB_OTG_Core, buff,sector,512 * count);
      USBH_MSC_HandleBOTXfer(&USB_OTG_Core ,&USB_Host);
      
      if(!HCD_IsDeviceConnected(&USB_OTG_Core))
      { 
        return RES_ERROR;
      }      
    }
    while(status == USBH_MSC_BUSY ); // Loop which create hanging state
  }
  
  if(status == USBH_MSC_OK)
    return RES_OK;
  return RES_ERROR;
  
}

The main problem is the loop which creates hanging state

while(status == USBH_MSC_BUSY );

So I do not know what to do to avoid this. Using debugger I discover that state is caused by parameter CmdStateMachine of structure USBH_MSC_BOTXferParam, type USBH_BOTXfer_TypeDef is equal CMD_UNINITIALIZED_STATE which actually cause miss up of switch statement of USBH_MSC_Read10 function.

/**
  * @brief  USBH_MSC_Read10 
  *         Issue the read command to the device. Once the response received, 
  *         it updates the status to upper layer
  * @param  dataBuffer : DataBuffer will contain the data to be read
  * @param  address : Address from which the data will be read
  * @param  nbOfbytes : NbOfbytes to be read
  * @retval Status
  */
uint8_t USBH_MSC_Read10(USB_OTG_CORE_HANDLE *pdev,
                        uint8_t *dataBuffer,
                        uint32_t address,
                        uint32_t nbOfbytes)
{
  uint8_t index;
  static USBH_MSC_Status_TypeDef status = USBH_MSC_BUSY;
  uint16_t nbOfPages;
  status = USBH_MSC_BUSY;
  
  if(HCD_IsDeviceConnected(pdev))
  {
    switch(USBH_MSC_BOTXferParam.CmdStateMachine)
    {
    case CMD_SEND_STATE:
      /*Prepare the CBW and relevant field*/
      USBH_MSC_CBWData.field.CBWTransferLength = nbOfbytes;
      USBH_MSC_CBWData.field.CBWFlags = USB_EP_DIR_IN;
      USBH_MSC_CBWData.field.CBWLength = CBW_LENGTH;
      
      USBH_MSC_BOTXferParam.pRxTxBuff = dataBuffer;
      
      for(index = CBW_CB_LENGTH; index != 0; index--)
      {
        USBH_MSC_CBWData.field.CBWCB[index] = 0x00;
      }
      
      USBH_MSC_CBWData.field.CBWCB[0]  = OPCODE_READ10; 
      
      /*logical block address*/
      
      USBH_MSC_CBWData.field.CBWCB[2]  = (((uint8_t*)&address)[3]);
      USBH_MSC_CBWData.field.CBWCB[3]  = (((uint8_t*)&address)[2]);
      USBH_MSC_CBWData.field.CBWCB[4]  = (((uint8_t*)&address)[1]);
      USBH_MSC_CBWData.field.CBWCB[5]  = (((uint8_t*)&address)[0]);
      
      /*USBH_MSC_PAGE_LENGTH = 512*/
      nbOfPages = nbOfbytes/ USBH_MSC_PAGE_LENGTH;  
      
      /*Tranfer length */
      USBH_MSC_CBWData.field.CBWCB[7]  = (((uint8_t *)&nbOfPages)[1]) ; 
      USBH_MSC_CBWData.field.CBWCB[8]  = (((uint8_t *)&nbOfPages)[0]) ; 
      
      
      USBH_MSC_BOTXferParam.BOTState = USBH_MSC_SEND_CBW;
      /* Start the transfer, then let the state machine 
      manage the other transactions */
      USBH_MSC_BOTXferParam.MSCState = USBH_MSC_BOT_USB_TRANSFERS;
      USBH_MSC_BOTXferParam.BOTXferStatus = USBH_MSC_BUSY;
      USBH_MSC_BOTXferParam.CmdStateMachine = CMD_WAIT_STATUS;
      
      status = USBH_MSC_BUSY;
      
      break;
      
    case CMD_WAIT_STATUS:
      
      if((USBH_MSC_BOTXferParam.BOTXferStatus == USBH_MSC_OK) && \
        (HCD_IsDeviceConnected(pdev)))
      { 
        /* Commands successfully sent and Response Received  */       
        USBH_MSC_BOTXferParam.CmdStateMachine = CMD_SEND_STATE;
        status = USBH_MSC_OK;      
      }
      else if (( USBH_MSC_BOTXferParam.BOTXferStatus == USBH_MSC_FAIL ) && \
        (HCD_IsDeviceConnected(pdev)))
      {
        /* Failure Mode */
        USBH_MSC_BOTXferParam.CmdStateMachine = CMD_SEND_STATE;
      }
      
      else if ( USBH_MSC_BOTXferParam.BOTXferStatus == USBH_MSC_PHASE_ERROR )
      {
        /* Failure Mode */
        USBH_MSC_BOTXferParam.CmdStateMachine = CMD_SEND_STATE;
        status = USBH_MSC_PHASE_ERROR;    
      }
      else
      {
        /* Wait for the Commands to get Completed */
        /* NO Change in state Machine */
      }
      break;
      
    default:
      break;
    }
  }
  return status;
}

Here is USBH_BOTXfer_TypeDef type declaration;

typedef struct _BOTXfer
{
uint8_t MSCState;
uint8_t MSCStateBkp;
uint8_t MSCStateCurrent;
uint8_t CmdStateMachine;
uint8_t BOTState;
uint8_t BOTStateBkp;
uint8_t* pRxTxBuff;
uint16_t DataLength;
uint8_t BOTXferErrorCount;
uint8_t BOTXferStatus;
} USBH_BOTXfer_TypeDef;

During the debug I discover that all fields of it is 0x00.

Here are my FatFs calls

int main(void)
{
    FATFS Fat;
    FIL file;
    FRESULT fr;
    
    RCC->AHB1ENR |= RCC_AHB1ENR_GPIODEN;
    
    /* Enable SWO output */
    DBGMCU->CR = 0x00000020;
    
    GPIOD->MODER=0x55000000;
    GPIOD->OTYPER = 0x00000000;
    GPIOD->OSPEEDR = 0x00000001;
    
    while(1)
    {   
        if (!USB_MSC_IsInitialized())
        {
            USB_MSC_Initialize();
        }
        
        if (USB_MSC_IsConnected())
        {
            GPIOD->ODR = (1 << 15);
            
            disk_initialize(0);
            
            fr = f_mount(0, &Fat);
            
            if(fr == FR_OK)
            {           
                fr = f_open(&file,"0:DP_lab8.pdf",(FA_CREATE_ALWAYS | FA_WRITE));
                
                if (fr == FR_OK)
                {
                    f_close(&file);
                }
                
                f_mount(0, NULL);
            }
        }
        else
        {
            GPIOD->ODR = (1 << 14);
        }
        
        USB_MSC_Main();
    }
}

USB_MSC_IsConnected function is:

int USB_MSC_IsConnected(void)
{
    if (g_USB_MSC_HostStatus == USB_DEV_NOT_SUPPORTED)
    {
        USB_MSC_Uninitialize();
    }
    
    return !(g_USB_MSC_HostStatus == USB_DEV_DETACHED ||
        g_USB_MSC_HostStatus == USB_HOST_NO_INIT ||
      g_USB_MSC_HostStatus == USB_DEV_NOT_SUPPORTED);
}

And device states are:

typedef enum
{
    USB_HOST_NO_INIT = 0,  /* USB interface not initialized */
    USB_DEV_DETACHED,      /* no device connected */
    USB_SPEED_ERROR,       /* unsupported USB speed */
    USB_DEV_NOT_SUPPORTED, /* unsupported device */
    USB_DEV_WRITE_PROTECT, /* device is write protected */
    USB_OVER_CURRENT,      /* overcurrent detected */
    USB_DEV_CONNECTED      /* device connected and ready */
} USB_HostStatus;

The value of g_USB_MSC_HostStatus is received by standard USB HOST user callbacks.

Answer 1

I think it is a bug in ST host library. I've hunted it down, as my usb host was unable to pass enumeration stage. After a fix the stack is Ok.

There is union _USB_Setup in usbh_def.h file in "STM32Cube/Repository/STM32Cube_FW_F7_V1.13.0/Middlewares/ST/STM32_USB_Host_Library/Core/Inc" (any chip, not only F7, any version, not only V1.13.0). It has uint16_t bmRequestType and uint16_t bRequest. These two fileds must be uint8_t as of USB specs. Fixing this issue made usb host go as needed. Enumeration stage passes ok, and all other stages as well.