Julius, On Tue, Dec 15, 2015 at 3:02 PM, Julius Werner <jwer...@chromium.org> wrote: > In A.D. 1582 Pope Gregory XIII found that the existing Julian calendar > insufficiently represented reality, and changed the rules about > calculating leap years to account for this. Similarly, in A.D. 2013 > Rockchip hardware engineers found that the new Gregorian calendar still > contained flaws, and that the month of November should be counted up to > 31 days instead. Unfortunately it takes a long time for calendar changes > to gain widespread adoption, and just like more than 300 years went by > before the last Protestant nation implemented Greg's proposal, we will > have to wait a while until all religions and operating system kernels > acknowledge the inherent advantages of the Rockchip system. Until then > we need to translate dates read from (and written to) Rockchip hardware > back to the Gregorian format. > > This patch works by defining Jan 1st, 2016 as the arbitrary anchor date > on which Rockchip and Gregorian calendars are in sync. From that we can > translate arbitrary later dates back and forth by counting the number > of November/December transitons since the anchor date to determine the > offset between the calendars. We choose this method (rather than trying > to regularly "correct" the date stored in hardware) since it's the only > way to ensure perfect time-keeping even if the system may be shut down > for an unknown number of years. The drawback is that other software > reading the same hardware (e.g. mainboard firmware) must use the same > translation convention (including the same anchor date) to be able to > read and write correct timestamps from/to the RTC. > > Signed-off-by: Julius Werner <jwer...@chromium.org> > --- > drivers/rtc/rtc-rk808.c | 48 ++++++++++++++++++++++++++++++++++++++++++++---- > 1 file changed, 44 insertions(+), 4 deletions(-)
I'm not terribly worried about the date in the past problem that you brought up in your own response. So: Reviewed-by: Douglas Anderson <diand...@chromium.org> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
