SD_IOE_RW_LEN
mmc_arg |= SD_IOE_RW_LEN(len_arg) | SD_IO_RW_INCR;
arg = SD_IOE_RW_LEN(blksz);
arg = SD_IOE_RW_BLK | SD_IOE_RW_LEN(b_count);
SD_IOE_RW_LEN(datalen);