HL8548 debug port

What is the purpose of HL8548 debug port (DEBUG_TX/DEBUG_RX)? Very hard to find information on it. I know, that on other devices I could use it for tracing, but what’s about HL8548? What additional software I need to work with this port?

i found the below APN

As per the APN, you need Mobile Analyser and 3G Firmware Trace Tool…