STM32_MDMA_CBNDTR_BNDT
cbndtr |= STM32_MDMA_CBNDTR_BNDT(len);
residue += STM32_MDMA_CBNDTR_BNDT(hwdesc->cbndtr);
hwdesc->cbndtr |= STM32_MDMA_CBNDTR_BNDT(len);