I looked a bit into this on my rooted phone:
Node permissions for /dev/rtc0 seem to be ok.
The RTC is running, but time cannot be set:
hwclock -w throws a “RTC_SET_TIME: Invalid argument” at me instead of setting the hardware clock.
The RTC time and date count “up” - today, after the phone was off over night, we have the 7th. of January instead of the 6th.
Searching the internet with Startpage and search term “Android RTC_SET_TIME: Invalid argument” shows up this interesting article: http://www.96boards.org/forums/topic/cant-set-rtc-time-on-dragon-board/
and I quote:
The way this is implemented in the codeaurora AOSP builds is that the RTC is kept read-only…
I know, we are not running “codeaurora” here, but my suspicion is a crappy kernel build with RTC write access not enabled.
This is probably bad news for those who want a workaround as we are at the mercy of the dev-team to fix this.