mtk_data_len
bm_ctl->sec = mtd->writesize / mtk_data_len(nand);
bm_ctl->pos = mtd->writesize % mtk_data_len(nand);
return nfc->buffer + i * mtk_data_len(chip);
return nfc->buffer + i * mtk_data_len(chip) + chip->ecc.size;
bad_pos += nand->bad_mark.sec * mtk_data_len(chip);