** Changed in: linux-raspi (Ubuntu)
Status: Confirmed => Invalid
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https://bugs.launchpad.net/bugs/1926911
Title:
hctosys not reading hardware clock on CM4
Status in ubuntu-core-initramfs:
New
Status in linux-raspi package in Ubuntu:
Invalid
Status in linux-raspi source package in Focal:
Fix Released
Bug description:
[Impact]
At boot, the kernel does not synchronize the system clock from an RTC,
if the driver that manages the RTC device is built as a module.
[Test Case]
$ dmesg|grep rtc
[ 1.593561] hctosys: unable to open rtc device (rtc0)
[ 10.767256] rtc-pcf85063 10-0051: registered as rtc0
[Where Problems Could Occur]
Loading of the relevant RTC module (which then triggers a clock sync
from the RTC) is handled by userspace. This could interfere with
systemd (or some other entity) hat handles clock sync'ing which could
yield unexpected results.
[Original Description]
There is a timing issue when using the CM4 with the official CM4 IO
baseboard.
The CM4 baseboard comes with a built in rtc and a battery holder by
default, to enable it a devicetree overlay needs to be enabled and a
matching module gets loaded ...
$ tail -2 /run/mnt/ubuntu-seed/config.txt
dtparam=i2c_vc=on
dtoverlay=i2c-rtc,pcf85063a,i2c_csi_dsi,addr=0x51
$ lsmod | grep pcf85063
rtc_pcf85063 20480 0
When booting the kernel runs hctosys about 1.5sec into the boot, the
rtc module only gets loaded about 10sec later though:
$ dmesg|grep rtc
[ 1.593561] hctosys: unable to open rtc device (rtc0)
[ 10.767256] rtc-pcf85063 10-0051: registered as rtc0
Looking at the systemd journal the clock does not get set at all, only
a network connection actually triggers setting of the clock (note the
timestamps in the journal):
---
Apr 26 10:27:53 ubuntu kernel: mmc0: SDHCI controller on fe340000.emmc2
[fe340000.emmc2] using ADMA
Apr 26 10:27:53 ubuntu kernel: hctosys: unable to open rtc device (rtc0)
Apr 26 10:27:53 ubuntu kernel: of_cfs_init
Apr 26 10:27:53 ubuntu kernel: of_cfs_init: OK
...
Apr 26 10:28:02 CM4 systemd[1]: Started Network Name Resolution.
Apr 26 10:28:02 CM4 kernel: rtc-pcf85063 10-0051: registered as rtc0
Apr 26 10:28:02 CM4 systemd-udevd[459]: Using default interface naming scheme
'v245'.
...
Apr 26 10:28:08 CM4 avahi.daemon[593]: Registering new address record for
192.168.2.32 on wlan0.IPv4.
Apr 26 10:28:08 CM4 systemd-timesyncd[495]: Network configuration changed,
trying to establish connection.
May 02 17:14:17 CM4 systemd-timesyncd[495]: Initial synchronization to time
server 91.189.89.199:123 (ntp.ubu>
May 02 17:14:17 CM4 systemd[1]: Starting Online ext4 Metadata Check for All
Filesystems...
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I think the loading of the rtc_pcf85063 module should trigger an
additional hctosys call (preferably from the module itself, but worst
case a udev rule calling out to hwclock --hctosys might work too)...
Just for the record, the hwclock works fine otherwise:
$ sudo hwclock
2021-05-02 19:56:11.281975+00:00
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