20h offset with DS3231 RTC

[Ian Lepore]

On Wed, 2019-11-20 at 23:42 +0100, Bernd Walter wrote:
> I just added an RTC to a Pi3B with FreeBSD 12.1-RELEASE:
> ds32310: <Maxim DS3231 RTC> at addr 0xd0 on iicbus0
> ...
> Setting date via ntp.
> 20 Nov 22:55:48 ntpdate[760]: step time server 46.165.221.137 offset
> 71999.728041 sec
> 
> This was the 3rd reboot.
> The first boot had no actual time as expected and the RTC wasn't even
> running.
> The second already showed the offset.
> 
> To verify I checked another systemm, wqhich I've added such an RTC
> before.
> dmesg said that it booted 9 days ago with 1s offset, but with another
> reboot:
> 20 Nov 23:31:44 ntpdate[826]: step time server 80.67.16.8 offset
> 72000.160415 sec
> 
> It seems that the error depends on the actual date/time.
> 

I think this is because of a bug/lack-of-capability in the rpi i2c
driver and/or hardware, and it affects all i2c devices that use some
common driver routines to read and write slave device "registers". 
I'll look into fixing it, hopefully within a day.

-- Ian