DMA vs MSGDMA

Hi Tomek,

I'm doing very similar thing as You do. My recommendation is definitely the mSGDMA. The source DMA is configured as "Memory-mapped to Streaming", the Sink DMA is configured as "Streaming to Memory Mapped". In between You implement your processing functions. I use standard ST-Packets to mark Image start and stop. I use also reserved memory which I define in device tree file and use for DMA transfers. This is because DMA needs physical address which is hard to get in Linux without implementing kernel modules. If you have reserved memory You can mmap this and access it from HPS ARM processor via virtual adress and give the physical adress in DMA descriptors. Enable "burst mode" to have higher performance. I'm not using IRQ based response channel in DMA, I'm counting symbols which are coming into sink DMA and read them out using Memory mapped PIO component. I also have compiled/ported some of the NIOS code of the software layer for creating the DMA descriptors for MSGDMA and schedule sync transfers.