RTC alarm wakeup from poweroff or disk-suspend

Hi,

I'm trying to use an external RTC clock (https://www.hardkernel.com/shop/rtc-shield/, battery is good) connected over I2C to wakeup the Odroid HC4 from poweroff (or if not possible from disk-suspend). To my surprise the rtc was already recognised (and also the device tree seems good) and I'm able to communicate with it, read it and set alarms for it. However, whenever I poweroff the device and try to turn on again it does not power on by itself (neither from poweroff, nor from disk suspend).

Output from /proc/driver/rtc:

rtc_time	: 19:16:28
rtc_date	: 2023-03-29
alrm_time	: 19:07:00
alrm_date	: 2023-04-29
alarm_IRQ	: no
alrm_pending	: no
update IRQ enabled	: no
periodic IRQ enabled	: no
periodic IRQ frequency	: 1
max user IRQ frequency	: 64
24hr		: yes

When setting an alarm using (same result using rtcwake)

echo `date '+%s' -d '+ 5 minutes'` | sudo tee /sys/class/rtc/rtc0/wakealarm

which sets the RTC to the following:

rtc_time	: 19:18:17
rtc_date	: 2023-03-29
alrm_time	: 19:23:00
alrm_date	: 2023-03-29
alarm_IRQ	: yes
alrm_pending	: no
update IRQ enabled	: no
periodic IRQ enabled	: no
periodic IRQ frequency	: 1
max user IRQ frequency	: 64
24hr		: yes

However, after power off (or suspend to disk), the Odroid HC4 does not turn on again.. After powercycling and the following boot, this is what /proc/driver/rtc looks like:

rtc_time	: 19:24:49
rtc_date	: 2023-03-29
alrm_time	: 19:23:00
alrm_date	: 2023-04-29
alarm_IRQ	: no
alrm_pending	: no
update IRQ enabled	: no
periodic IRQ enabled	: no
periodic IRQ frequency	: 1
max user IRQ frequency	: 64
24hr		: yes

which somehow has a wrong alarm date and the alarm_IRQ is no, and no alarm is pending.

The OS I'm using is the following:

Linux odroidhc4two 6.1.11-meson64 #23.02.2 SMP PREEMPT Sat Feb 18 00:07:55 UTC 2023 aarch64 aarch64 aarch64 GNU/Linux
Armbian 23.02.2 Jammy with Linux 6.1.11-meson64

Would be nice if someone could help me..

Best,

trembel