AM2432: PCIe Swing tuning, de-emphasis, pre-emphasis, self biasing

Tool/software:

According to this post, Swing tuning is not supported, TM bit just for test purpose. 

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1168552/am6442-pcie-voltage-swing-tunning

#1. What is mean for test purpose? can this bit be changeable and effective? 

#2. Other features regarding de-emphasis, pre-emphasis, equalization, also not support? or not recommend to change? But from this post, it is configurable.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1427955/tda4ap-q1-how-to-set-pcie0-transmitter-de-emphasis

#3. Are these feature not recommended to configure, or not supported to configure?

#4. Is the Serdes self-biased?