ADAU 1772 : No device ID, need a "static" register for a manufacturing test

We're using the ADAU1772 in a device that is going through some automated QC - with all of our other I2C devices, we use the device ID or rev information as the baseline test for functionality. If those come back bad, device gets pulled and onward ho to the next one instead of doing the remaining tests. There are only a handful of Read only  registers on the ADAU1772, and it's not clear to me what the reserved bits in some of them would look like after boot, or if they can change at all - also if they're all 0's that isn't exactly a great test beyond an ACK from the ADAU.

Short is - is there a set of bits that doesn't change, is non-zero valued in at least one bit, and that we could use in lieu of the device ID to quickly test the comm?