Question about PCF85063A invalid state

Hi,

We're using the PCF85063A on our Compute Module 4 I/O board, and a number of 
users have experienced problems with invalid state after inserting a backup 
battery. So far the problem has been confined to EXT_TEST (bit 7 of CTRL_1) 
being set, but there are a number of registers for which the driver only 
modifies a subset of the bits.

I can think of a number of ways to clear this invalid state, none of which are 
difficult - force a software reset whenever certain bits of certain registers 
have certain values, always specifically force some bits to known values, etc. -
but are there any preferences or pitfalls to be aware of?

Thanks for your input,

Phil Elwell, Raspberry Pi