STM32_MDMA_CTBR
stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id)));
stm32_mdma_write(dmadev, STM32_MDMA_CTBR(id), hwdesc->ctbr);
ctbr = stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id));
ctbr = stm32_mdma_read(dmadev, STM32_MDMA_CTBR(chan->id));