USBD MSC does not support more than 2 luns

[xu-yingjing]

Hello,

In the function MSC_BOT_CBW_Decode() of the file usbd_msc_bot.c, there is the following judgment:

  if ((USBD_LL_GetRxDataSize(pdev, MSCOutEpAdd) != USBD_BOT_CBW_LENGTH) ||
      (hmsc->cbw.dSignature != USBD_BOT_CBW_SIGNATURE) ||
      (hmsc->cbw.bLUN > 1U) || (hmsc->cbw.bCBLength < 1U) ||
      (hmsc->cbw.bCBLength > 16U))
  {
    SCSI_SenseCode(pdev, hmsc->cbw.bLUN, ILLEGAL_REQUEST, INVALID_CDB);

    hmsc->bot_status = USBD_BOT_STATUS_ERROR;
    MSC_BOT_Abort(pdev);
  }
  else
  {
    /* ... */
  }

As shown in the above code, when (hmsc->cbw.bLUN > 1U) is established, it will be judged as an illegal request. Therefore, the legal value of hmsc->cbw.bLUN can only be 0 or 1. For this reason, USBD MSC can only support a maximum of 2 luns.

Why not add a MSC configuration macro definition in the file usbd_conf_template.h to configure the maximum number of luns supported?

[ALABSTM]

See also STM32CubeL4#41

[ALABSTM]

ST Internal Reference: 126925

[ALABSTM]

Hi @xu-yingjing,

Our development teams acknowledged your request and agreed with the principle. However, there is currently no plan to address it. I will keep you informed should there be any news.

The request has been already logged internally. It will be tracked on GitHub via this issue (mentioned above). Please allow me to close this one. Thank you for your comprehension.

With regards,