The subsystem connects to other hardware components to construct a complete HDMI 2.1 TX system. These hardware components usually are different from device to device. You must fully understand the system and adjust the subsystem parameters accordingly.
The HDMI 2.1 TX Subsystem is controlled over an AXI4-Lite interface using the Xilinx API described in Application Software Development; the appendix also describes how to integrate the subsystem API into a software application. The API is the only provided control for the HDMI TX subsystems and the register interface descriptions are not provided.