I have a Debian/Raspbian buster Linux on a Raspberry Pi 4 with isl1208 RTC attached. I think the RTC itself works: I can read it directly with a python script when kernel module disabled
command shows RTC clock and
hwclock -r does not work:
$ sudo hwclock -r hwclock: select() to /dev/rtc0 to wait for clock tick timed out
hwclock should be used during boot to set the system time from RTC.
Any ideas why
hwclock -r does not work? Or should there be some other way to set system time from RTC during boot?
It seems that systemd can read the RTC, because systemd-timedated only does read operation on /dev/rtc, which works fine.
hwclock -r before reading time from /dev/rtc first does synchronize_to_clock_tick_rtc where the process waits for the interrupt, which never comes.
So I wonder if that update interrupt should even work with isl1208 and RasPi, where there is only i2c connection between the RTC i2c IC and RasPi?