Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Silicon Labs/SiM3_NRND/SIM3U167_B/USB_0/FADDR#0x0
FADDRUPD=NOT_SET
Function Address
Function Address.
Function Address Update.
0 (NOT_SET): The last address written to FADDR is in effect.
1 (SET): The last address written to FADDR is not yet in effect.
https://github.com/cmsis-svd/cmsis-svd-data