SPRUIL1D May 2019 – December 2024 DRA829J , DRA829J-Q1 , DRA829V , DRA829V-Q1 , TDA4VM , TDA4VM-Q1
The Quality-of-Service (QoS) mechanism in the PCIe subsystem uses the Virtual Channel/Traffic Class (VC/TC) feature in the PCIe core in conjunction with the CBA QoS capabilities.
For ingress traffic, transactions that use the highest enabled virtual channel will be directed to the high priority master interface. Transactions using all other virtual channels will be directed to the low priority master interface.
In addition, the TC information from each transaction on the AXI master information is mapped to the CCHANID signal of the VBUSM master interface. The system level interconnect can use the CCHANID along with the orderid for QoS purposes. Table 12-246 shows the TC mapping to the 12-bit CCHANID of each VBUSM master interface.
| TC Value | CCHANID[11:0] |
|---|---|
| 0 | {9’d0, 3’b000} |
| 1 | {9’d0, 3’b001} |
| 2 | {9’d0, 3’b010} |
| 3 | {9’d0, 3’b011} |
| 4 | {9’d0, 3’b110} |
| 5 | {9’d0, 3’b101} |
| 6 | {9’d0, 3’b110} |
| 7 | {9’d0, 3’b111} |
For egress traffic, the data presented on the VBUSM high priority port will be assigned the highest enabled VC. This will ensure that data on the high priority port will get priority on the PCIe link. All data presented on the VBUSM low priority port will be assigned lower VCs.