From https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=f...

commit f076ef44a44d02ed91543f820c14c2c7dff53716 Author: Julius Werner jwerner@chromium.org Date: Tue Dec 15 15:02:49 2015 -0800

rtc: rk808: Compensate for Rockchip calendar deviation on November 

31st

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.