The PS DDR enables traffic classes in the controller via the DDRC.PCFGQOS0 and DDRC.PCFGWQOS0 registers. These registers assign DDRC traffic classes based on the incoming ARQOS/AWQOS signals coming from the PS interconnect override register or on the AXI transactions from individual peripherals. The traffic classes are set as per the following table:
Incoming AxQoS [3:0] |
Traffic Class |
---|---|
Read Channel |
|
0000-0011 |
Best Effort |
0100-1011 |
Video |
1100-1111 |
Low Latency |
0100-1011 |
Timeout - Expired Video |
Write Channel |
|
0000-0111 |
Best Effort |
1000-1111 |
Video |
1000-1111 |
Timeout - Expired Video |
The AXI slave interfaces by default are set to override an AXI QOS value of 0. This results in PS DDR best effort regardless of the PL AXI_QOS signal on the interface via the AFIFM register module. For more information, see the DDR QoS Controller section of Zynq UltraScale All Programmable MPSoC Technical Reference Manual (UG1085) [Ref 1] .