Watchdog (/dev/watchdog0)not getting disabled - jetson nano

[nirav.jani]

Need to exit from application gracefully after kicking watchdog last time…(application on jetson nano - Package: nvidia-jetpack Version: 4.5.1-b17)

Application opened up the watchdog as below…
open(“/dev/watchdog0”, O_RDWR);

to keep watchdog alive, application calls at regular interval (interval < timeout for wdg set previously)
ioctl(fd, WDIOC_KEEPALIVE, NULL);

Want to exit from application gracefully - e.g. disabling reboot of system through watchdog with below code…
int options = WDIOS_DISABLECARD;
ret = ioctl(fd, WDIOC_SETOPTIONS, &options);

Above call of disabling wdg returns value -1 and seems the watchdog is not getting disabled by this call, which later causes the system to reboot with watchdog timer. (visible in /var/log/syslog as last reboot happened due to PMIC watchdog reset)

Is there a way using which I can disable the watchdog before exiting from application and prevent system reboot by watchdog? Any steps I am following wrong here ?

Any guidance would be of great help!

[ShaneCCC]

Have a reference to below code to change the timeout time.

https://code.woboq.org/linux/linux/tools/testing/selftests/watchdog/watchdog-test.c.html

[nirav.jani]

Thanks Shane for reply and useful example !

I found below messages in my /var/log/syslog - which clearly indicates why I am not able to disable watchdog…the same is the case with above example and the program which I was experimenting with.

19900 Mar 29 11:04:03 XXXX-desktop kernel: [59549.391547] watchdog: watchdog0: nowayout prevents watchdog being stopped!
19901 Mar 29 11:04:03 XXXX-desktop kernel: [59549.391551] watchdog: watchdog0: watchdog did not stop!

20533 Mar 29 11:06:29 XXXX-desktop kernel: [    1.445512] last reset is due to pmic watchdog timeout

This indicates that the kernel (coming with nvidia-jetpack 4.5.1) mostly has been compiled with CONFIG_WATCHDOG_NOWAYOUT - flag enabled or set to value 1.

Is there a way I can disable this flag to false without recompiling the kernel ? Probably this may help me in disabling watchdog.

Thanks for your reply in advance!

[ShaneCCC]

Watchdog won’t trigger reboot if system alive in default system configure.
There is no way to disable it without kernel reconfigure and compile.

[nirav.jani]

Thanks Shane for quick reply!

The first statement last part was not clear - request to clarify it further… e.g. “system alive in default system configure”. What I understand from last statement is: we have only option to reconfigure/re compile the kernel to disable this flag(CONFIG_WATCHDOG_NOWAYOUT) - that is the only way out (for preventing system reboot by watchdog)- hope I am clear on my understanding…

[ShaneCCC]

If system keep alive(CPU alive) watchdog won’t reboot the system no need to reconfigure the kernel.