OSPI Direct Access by PMC DMA via CCI

Versal ACAP Technical Reference Manual (AM011)

Document ID
AM011
Release Date
2022-04-26
Revision
1.4 English

As described by the direct mode feature in the OSPI Memory Access Modes section, the PMC DMA should not be used to move data from the flash device to memory via the FPD CCI.

Doing so can starve the transactions of the GEM DMA controller. This is because the path from the PMC DMA and LPD GEM controllers are both via the LPD main switch, FPD MMU TCU 0 and to the CCI ACE-lite 3 ingress port.

This situation can be seen in the PMC-PS-CPM Interconnect Diagram where the DMA traffic from PMC goes through the LPD main switch where the shared path with the GEM DMA going to the FPD CCI.