DP83869HM: Query on disabling register access through pin option

Part Number: DP83869HM

Tool/software:

Hi team, 

We are using DP83869HMRGZT in one of our projects. 

We are debugging an int function that is not working as expected. At the time, we saw this description mentioned: "When register access is disabled through pin option."

How does this work, and how can we make sure register access is not disabled in my case?

Thanks 
Yovel raja