STM32_DMA_MAX_BURST
dst_maxburst = STM32_DMA_MAX_BURST;
best_burst = stm32_dma_get_best_burst(len, STM32_DMA_MAX_BURST,
dd->max_burst = STM32_DMA_MAX_BURST;
src_maxburst = STM32_DMA_MAX_BURST;