SPRUGR9H November 2010 – April 2015 66AK2E05 , 66AK2H06 , 66AK2H12 , 66AK2H14 , 66AK2L06 , AM5K2E02 , AM5K2E04 , SM320C6678-HIREL , TMS320C6652 , TMS320C6654 , TMS320C6655 , TMS320C6657 , TMS320C6670 , TMS320C6671 , TMS320C6672 , TMS320C6674 , TMS320C6678
For transmit, the TX DMA engine uses the information found in the descriptor fields to determine how to process the TX packet. For receive, the RX DMA uses a flow. A flow is a set of instructions that tells the RX DMA how to process the RX packet. It is important to note that there is not a correspondence between RX channel and RX flow, but rather between RX packet and RX flow. For example, one peripheral may create a single RX flow for all packets across all channels, and another may create several flows for the packets on each channel.
For loopback PKTDMA modes (i.e. infrastructure cases), the RX flow is specified in the TX descriptor, in the SOURCE_TAG_LO field. The PKTDMA will pass this value to the streaming I/F as flow index. In non-loopback cases, the RX flow is specified in the packet info structure of the Streaming I/F. In the event no RX flow is specified, the RX DMA will use RX flow N for RX channel N.