I spent a brief bit of time this evening documenting how to reproduce the problem. It is simple for me to reproduce. I re-loaded a fresh copy of the OSBo Ubuntu image onto a uSD card. Here’s the entire transcript of all I did after booting it.
login as: ubuntu
[email protected]’s password:
Welcome to Ubuntu 14.04 LTS (GNU/Linux 3.8.13-bone56 armv7l)
* Documentation: https://help.ubuntu.com/
Last login: Sat Jun 27 00:15:32 2015 from 192.168.1.103
ubuntu@arm:~$ sudo su
[sudo] password for ubuntu:
root@arm:/home/ubuntu# echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
root@arm:/home/ubuntu# dmesg | grep -i rtc
[ 0.000000] Kernel command line: console=tty0 console=ttyO0,115200n8 root=/dev/mmcblk0p2 ro rootfstype=ext4 rootwait fixrtc
[ 2.040391] omap_rtc 44e3e000.rtc: rtc core: registered 44e3e000.rtc as rtc0
[ 2.047851] 44e3e000.rtc: already running
[ 2.584010] [drm] Cannot find any crtc or sizes – going 1024×768
[ 2.720847] omap_rtc 44e3e000.rtc: setting system clock to 2015-06-27 00:16:27 UTC (1435364187)
[ 152.593546] rtc-ds1307 1-0068: rtc core: registered ds1307 as rtc1
[ 152.593616] rtc-ds1307 1-0068: 56 bytes nvram
root@arm:/home/ubuntu# hwclock -f /dev/rtc1 -r
Sat 27 Jun 2015 12:19:36 AM UTC -0.271957 seconds
root@arm:/home/ubuntu# hwclock -f /dev/rtc1 -r
hwclock: ioctl(RTC_RD_TIME) to /dev/rtc1 to read the time failed: Input/output error
root@arm:/home/ubuntu# hwclock -f /dev/rtc1 -r
hwclock: ioctl(RTC_RD_TIME) to /dev/rtc1 to read the time failed: Input/output error
root@arm:/home/ubuntu#