Hi dear forums members, we're working with Appro IPNC ref and we came across the usage of EDMA, especially in DSP domain.
As it seems, there are a max of 64 channels for a particular queue but after we've looked all over the code base (mcfw + ti section) we found only 2 *** officially *** used channels: 8 in VA_LINK and 6 in FD_LINK. Still, we believe others might be also used (we're especially interested in VA use-case flow). As we couldn't find any declared mapping of use / don't use channels we require to know the following:
1. What's the meaning of VA_LINK_EDMA3_QUEUE_ID and how it affects the usage of DMA in the system? Could I use different queue ID if I wish under DSP?
2. We saw usage of "EDMA Channel Registers for Shadow region 5" - how does it affects DSP usage? Does each CPU (M3, Cortex, DSP) have a dedicated region?
3. Are all channels shared by the entire system i.e. if some code under VPSS (M3) uses channel id 3, does it means it's locked from DSP usage? Is there some mean to know who is using what channel?
4. I read something about linked EDMA activation but couldn't figure out exactly how it should be configured. If I have 3 buffers (different ptr, different size) that I wish to move via single EDMA async event, how can I do it?
Thanks in advance,
Roei