IMX6 Watchdog does not reset when kernel boot hangs

[vladzouth]

I'am working on a custom board based on IMX6Solo processor and TX6S-8035 module from KARO. I would like to enable watchdog. I build an image with fsl-comminuty-bsp (krogoth) and enable watchdog which is available as /dev/watchdog - /dev/watchdog0. I enable watchdog by passing watchdog parameters on kernel command line :

noinitrd console=ttymxc1,115200 ro debug panic=1 root=PARTUUID=0cc66cc0-02 rootwait earlyprintk=serial,ttymxc1,115200 imx2-wdt.nowayout imx2-wdt.timeout=45 

I implemented to the watchdog service to kick the watchdog so that reboot can't be happens on normal using. When i stop watchdog service, the system reboot and i can see that this is du to watchdog reset. But sometimes, the kernel boot hangs and the watchdog don't reboot the system.

Does somebody has any idea for the issue
Best regards,

Vladzouth

[vladzouth]

Hi Yuri,

Thank you for the response.
I do not understand what do you means about removing power? I use a custom board based on tx6s-8035 SOM and the components are physically connected. I can not isolate the SOM power from the rest of circuit.
To come back on my issue, the watchdog reset is ok when the system boot succeeds and the services are running but when the kernel stucks on boot somewhere, the watchdog reset does not work. 

[Yuri]

Hello,

  generally i.MX6 has no WDOG issues, except may be erratum ERR005768

(ROM: In rare cases, secondary image boot flow may not work due to
mis-sampling of the WDOG reset).

https://www.nxp.com/docs/en/errata/IMX6SDLCE.pdf 

   Perhaps, in Your case the WDOG reset occurs, but because of the mentioned

problems concerning improper states of external components, critical for rebooting,

the system hangs. 

Regards,

Yuri.

[Yuri]

Hello,

      It is highly recommended to remove power (voltage source) for all components on
board even only  a processor reset occurs. This avoids problems concerning improper

states of external components, critical for rebooting the processor.

So, the POR may be recommended for reboot (via WDOG).

Have a great day,

Yuri

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