On page 126 of the
Zynq-7000 TRM (UG585 v1.7) it states that:
"The first-level arbitration is based on the priority indicated by the AXI QoS signals from the master or programmable registers. The highest QoS value has the highest priority."
There is a subsequent paragraph on the much more complex "Advanced QoS" that relies on the CoreLink QoS-301 control registers.
However, the "basic QoS" should be sufficient, though the TRM does not seem to document how to determine the values for the QoS signals for different peripherals.
I need to set higher priority for the DMA controller than for the Masters (USB, GEM, SD controllers in the PS).
Is this possible (without using the Advanced QoS features of the CoreLink QoS-301), and if so how?
QoS for the PS AXI masters can be controlled only by the QoS-301.
The QoS mechanism was introduced in AXI-4.
All of the PS masters are AXI3 and do not have QoS signals.
As a result QoS-301 is used to control the priority for the masters.
Please refer to figure 9-1 in TRM,
"QoS" block is outside DMA IP core.
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