Watchdog restarts even though it is kicked

[harisp]

imx6ul watchdog not stopping

Hi all,

I am using imx6ul and I am trying to use the watchdog.

I have used  in my board's .h file 

   #define CONFIG_IMX_WATCHDOG  

to enable the watchdog.

Then I go to /uboot_folder/drivers/watchdog/imx_watchdog.c  and check what is done:

#ifdef CONFIG_IMX_WATCHDOG
void hw_watchdog_reset(void)
{
struct watchdog_regs *wdog = (struct watchdog_regs *)WDOG1_BASE_ADDR;

writew(0x5555, &wdog->wsr);
writew(0xaaaa, &wdog->wsr);
}

void hw_watchdog_init(void)
{
struct watchdog_regs *wdog = (struct watchdog_regs *)WDOG1_BASE_ADDR;
u16 timeout;

/*
* The timer watchdog can be set between
* 0.5 and 128 Seconds. If not defined
* in configuration file, sets 128 Seconds
*/
#ifndef CONFIG_WATCHDOG_TIMEOUT_MSECS
#define CONFIG_WATCHDOG_TIMEOUT_MSECS 128000
#endif
timeout = (CONFIG_WATCHDOG_TIMEOUT_MSECS / 500) - 1;
writew(WCR_WDZST | WCR_WDBG | WCR_WDE | WCR_WDT | WCR_SRS |

SET_WCR_WT(timeout), &wdog->wcr);

hw_watchdog_reset();
}
#endif

I then start my board which runs embedded linux, the board actually restarts  after 128 seconds.

However, I try to kick the watchdog by using the following script:

while [ 1 ] ; do sleep 1; echo x > /dev/watchdog; done

I run this script, the watchdog replies 

root@ccimx6ulstarter:~# ./script
watchdog watchdog0: watchdog did not stop!
watchdog watchdog0: watchdog did not stop!
......

......

......

watchdog watchdog0: watchdog did not stop!
watchdog watchdog0: watchdog did not stop!

U-Boot dub-2015.04-r5.4+ga397dea (Jan 13 2017 - 15:09:55)

CPU: Freescale i.MX6UL rev1.1 528 MHz (running at 396 MHz)
CPU: Industrial temperature grade (-40C to 105C) at 40C
Reset cause: WDOG
I2C: ready
DRAM: 256 MiB

......

......

......

So despite the fact that I am kicking the watchdog, the watchdog restarts. 

The same happens when I use command

watchdog -t 10 /dev/watchdog

The only way of making the system work is not using the WCR_WDE flag. When I do this, the watchdog does not start automatically, but I can start it with

echo V > /dev/watchdog

Then the watchdog starts and with my script I can kick it and when the script ends it restarts. However, I want the watchdog to start automatically with WCR_WDE flag.

How can I solve this problem?

Thanks

[igorpadykov]

Hi Haris

WCR_WDE is a write one once only bit as described in

sect.57.7.1 Watchdog Control Register (WDOGx_WCR)  i.MX6UL Reference Manual

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6ULRM.pdf

So if it is set in uboot, it can not be changed in linux.

Best regards
igor
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[harisp]

Thanks for the reply,

however, if I do not enable the watchdog in the uboot, then if an error occurs during booting, the system won't restart. But if I do set it in uboot, then I can't stop it by kicking it. What should I do?

[igorpadykov]

you can try to enable it in linux using Chapter 48
Watchdog (WDOG) Driver attached Linux Manual.

~igor

[harisp]

Hi,

Thanks for the quick reply.

I can enable it in linux by writing V to /dev/watchdog. This starts it.

However, if I don't enable it in uboot, then if the system fails during boot time, the watchdog doesn't restart the system. I do over the air updates and usually the root file system does not get updated correctly and so I need to start the watchdog in the bootloader. But I want to start it in the bootloader and be able to kick it from linux. How can I do that?

Thanks

[thomas-pub]

Any news on that ? I'm also having the same issue...