Re: rtc-palmas: correct for bcd year

From: Alexandre Belloni
Date: Fri Jul 08 2016 - 10:10:46 EST

On 05/01/2016 at 08:08:50 -0800, Mark Salyzyn wrote :
> On 01/04/2016 04:00 PM, Alexandre Belloni wrote:
> > I'd say that the proper course of action is to refuse to set dates
> > before 2000 and after 2100. See
> >
> Got it.
> We have an issue though, Android (or rather any embedded) devices must
> continue to function when date is manually set to any value between 1970 and
> 2037. The issue here is a fresh device with a recently charged battery will
> _start_ at 1970 until ntp or cell time/date/locale is set and the device
> must continue to function in this vacuum. A device reboot should not result
> in the other calendar values being reset, should the year be wrong, as this
> will result in a bad user experience.
> We will have to use a different patch on Android than upstream if dates
> before 2000 are deprecated.
> All other factors (rollover, leap) can be corrected by frameworks and
> runtime since the rtc is generally secondary (ie: first rtc driver was in
> 1979, created a daemon to correct the flaws in the hardware clock using a
> cron job)

Well, I was still thinking about that issue but while handling properly
a gap in the RTC continuity is impossible, it is actually easy to handle
an offset in the RTC by using mktime and then offseting the resulting
time_t. Of course you'll then need to handle leap years and the likes
but you said that was not an issue for you.

Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering