BD_MAX_BUFF_SIZE
actual_length = max_len_bds * BD_MAX_BUFF_SIZE;
remaining = req->usb_req.length % BD_MAX_BUFF_SIZE;
remaining = req->usb_req.length / BD_MAX_BUFF_SIZE;
if (req_len > BD_MAX_BUFF_SIZE) {
dword2 |= BD_MAX_BUFF_SIZE;
req_len -= BD_MAX_BUFF_SIZE;
buf_add += BD_MAX_BUFF_SIZE;