In this application, you will only have one DMA command active at a time, so all of your operations will use 0 as the DMA tag.
在这个应用程序中，一次只有一个dma命令是激活的，所以所有的操作都将使用0作为DMA标签。
2
When the command is written, the DMA request is enqueued into the MFC provided it has available slots -- yours certainly does as you are not doing any other concurrent DMA requests.
DMA transfers are almost always done by the SPEs rather than by the PPE because they can handle much more data and many more active DMA operations than the PPE.