Hi all,
I am playing maaxboard-mini(i.MX8MM ,yocto sumo, kernel 4.14) with my rtc chip M41T93,
after I set rtc with command: date --set="20210924 20:56:30";hwclock --systohc --utc --rtc=/dev/rtc0 and read it with "hwchock -r" , the date is right. I make sure the rtc works in this kernel
but after reboot, the date and rtc date that reading with hwclock -r both are wrong(it not shows my compilation time, it shows Aug, 26 XXXX)
and I try to use /sbin/hwclock --hctosys to get date, the date are same wrong.
after I remove ntpd.service at /etc/systemd/system/multi-user.target.wants/ntpd.service to disable it
after rebooting and reseting the rtc, and use /sbin/hwclock --hctosys in bootup script, the rtc works well( the date and rtc sync)
it seems ntpd.service make my rtc setting wrong? why? ( I tried yocto zeus, no this issue)
at the first, I think my rtc not work,Maybe the kernel has issue,but I use a scope to check the timing, I find it seems OK. now I think the issue is from ntpd.service
any help?
thanks.
please see the log:
cat /var/log/syslog | grep rtc
Aug 26 14:27:51 fortress kernel: [ 1.713541] imx-drm display-subsystem: bound imx-lcdif-crtc.0 (ops lcdif_crtc_ops)
Aug 26 14:27:51 fortress kernel: [ 4.721802] hctosys: unable to open rtc device (rtc0)
Aug 26 14:27:51 fortress kernel: [ 9.033299] rtc-m41t93 spi0.0: rtc core: registered rtc-m41t93 as rtc0
--
at the first, the log shows :hctosys: unable to open rtc device (rtc0) ,
but finally rtc-m41t93 spi0.0: rtc core: registered rtc-m41t93 as rtc0
the issue is from there?
my yocto sumo and zeus (kernel 4,14 and 5.4) kernel config are same: sync NTP and startup read from rtc
