Watchdog on odroid xu4

I've installed the latest available version for my board (Armbian_21.05.4_Odroidxu4_buster_legacy_4.14.222) and upgrade the Kernel to 5.4.125

Now, I'm wondering If the watchdog was supposed to work (I do have /dev/watchdog and installed the watchdog package with apt).

But it seems there is a problem, here is what I tried:

odroidxu4:~:# service watchdog status                
● watchdog.service - watchdog daemon
   Loaded: loaded (/lib/systemd/system/watchdog.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2021-08-23 17:07:20 CEST; 1h 5min ago
  Process: 2295 ExecStartPre=/bin/sh -c [ -z "${watchdog_module}" ] || [ "${watchdog_module}" = "none" ] || /sbin/modprobe $watchdog_module (code=exited, status=0/SUCCESS)
  Process: 2296 ExecStart=/bin/sh -c [ $run_watchdog != 1 ] || exec /usr/sbin/watchdog $watchdog_options (code=exited, status=0/SUCCESS)
 Main PID: 2298 (watchdog)
    Tasks: 1 (limit: 4447)
   Memory: 916.0K
   CGroup: /system.slice/watchdog.service
           └─2298 /usr/sbin/watchdog

Aug 23 17:07:20 odroidxu4 watchdog[2298]: temperature: no sensors to check
Aug 23 17:07:20 odroidxu4 watchdog[2298]: no test binary files
Aug 23 17:07:20 odroidxu4 watchdog[2298]: no repair binary files
Aug 23 17:07:20 odroidxu4 watchdog[2298]: error retry time-out = 60 seconds
Aug 23 17:07:20 odroidxu4 watchdog[2298]: repair attempts = 1
Aug 23 17:07:20 odroidxu4 watchdog[2298]: alive=/dev/watchdog heartbeat=[none] to=root no_act=no force=no
Aug 23 17:07:20 odroidxu4 watchdog[2298]: cannot set timeout 60 (errno = 22 = 'Invalid argument')
Aug 23 17:07:20 odroidxu4 watchdog[2298]: hardware watchdog identity: S3C2410 Watchdog
Aug 23 17:07:20 odroidxu4 watchdog[2298]: cannot set scheduler (errno = 1 = 'Operation not permitted')
Aug 23 17:07:20 odroidxu4 systemd[1]: Started watchdog daemon.

odroidxu4:~:# fuser -v /dev/watchdog                 
                     USER        PID ACCESS COMMAND
/dev/watchdog:       root       2298 F.... watchdog
odroidxu4:~:# dmesg|grep watchdog   
[    4.544359] s3c2410-wdt 101d0000.watchdog: watchdog inactive, reset disabled, irq disabled
odroidxu4:~:# echo "V" >/dev/watchdog                
zsh: device or resource busy: /dev/watchdog

Is the watchdog in general available for this board? What else shall I check?

Edited August 23, 20215 yr by angrest
typo