The PMC DMA should not be used to move data from the flash device to memory via the FPD CCI when the GEM Ethernet MAC controller performance is needed.
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 SMMU TCU 0 and to the CCI ACE-lite 3 ingress port.
This situation can occur when the PMC DMA accesses the direct memory access mode of the OSPI flash memory interface.
This situation can be seen in the PS and PMC Interconnect Architecture where the DMA traffic from PMC goes through the LPD main switch with the shared path with the GEM DMA going to the FPD CCI.
The PMC DMA should not be used to move data from the flash device to memory via the FPD CMN when the GEM Ethernet MAC controller performance is needed.
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 SMMU TCU 0 and to the RN-I ingress port of the CMN.
This situation can occur when the PMC DMA accesses the direct memory access mode of the OSPI flash memory interface.
This situation can be seen in the Detailed Interconnect Diagram where the DMA traffic from PMC goes through the LPD main switch with the shared path with the GEM DMA going to the SMMU Split Switch and FPD CMN.