[U-Boot] OMAP watchdog timer reset on BBB

[Suniel Mahesh]

On 13/09/19 23:28, Grygorii Strashko wrote:
> 
> 
> On 12/09/2019 19:33, Sam Protsenko wrote:
>> Hi Stefan,
>>
>> On Thu, Sep 12, 2019 at 5:38 PM Stefan Roese <sr at denx.de> wrote:
>>>
>>> Hi Sam,
>>>
>>> On 12.09.19 15:45, Sam Protsenko wrote:
>>>> Hi Suniel,
>>>>
>>>> After transition to DM WDT, watchdog timer on BeagleBone Black resets
>>>> the board after 1 minute or so. I'm using this defconfig: [1]. After
>>>> disabling CONFIG_WDT and CONFIG_WATCHDOG options the board doesn't
>>>> reset. I guess it might be happening on other boards using
>>>> CONFIG_WDT_OMAP3 as well. The issue can be reproduced by stopping in
>>>> U-Boot shell (=>) and waiting for 1 minute.
>>>>
>>>> Do you know by chance why it might be happening, or maybe some fix
>>>> already exists?
>>>>
>>>> Thanks!
>>>>
>>>> [1] https://pastebin.ubuntu.com/p/Zz5bY6cYXS/
>>>
>>> So you have enabled the watchdog and should see something like this
>>> upon bootup:
>>>
>>> WDT:   Started without servicing (60s timeout)
>>>
>>> Is this correct? Then you need to enable the U-Boot internal WDT
>>> servicing by enabling CONFIG_WATCHDOG as well, as this will
>>> result in the internal U-Boot servicing of the watchdog. Then
>>> you should see this upon bootup and no reset will appear in
>>> U-Boot:
>>>
>>> WDT:   Started with servicing (60s timeout)
>>>
>>
>> I'm seeing this ("with servicing") line, and CONFIG_WATCHDOG is
>> already enabled in am335x_evm_defconfig. So I think it's an issue,
>> which *probably* appeared when watchdog drivers were converted to
>> Driver Model (this defconfig is using CONFIG_WDT + CONFIG_WDT_OMAP3
>> options). Any clues what can be wrong?
>>
>>> Does this help?
> It seems logic of hw_watchdog_reset() and omap3_wdt_reset() is different.
> Pay attention at wdt_trgr_pattern.

Didn't do anything different. It was just a replication of hw_watchdog_reset() logic into omap3_wdt_reset().

in hw_watchdog_reset: a global variable "wdt_trgr_pattern" is assigned a value and written into register
static unsigned int wdt_trgr_pattern = 0x1234;
wdt_trgr_pattern = ~wdt_trgr_pattern;
writel(wdt_trgr_pattern, &wdt->wdtwtgr);

in omap3_wdt_reset:  as per DM, all glob var's must be part of drivers private structure
so initialised priv->wdt_trgr_pattern = 0x1234; and then written into register
priv->wdt_trgr_pattern = ~(priv->wdt_trgr_pattern);
writel(priv->wdt_trgr_pattern, &priv->regs->wdtwtgr);

> 
> It seems that
>      priv->wdt_trgr_pattern = 0x1234;
> need to be moved in omap3_wdt_probe()

As per my understanding the above change will not make any difference, because its just initialization of the variable.
should be ready before its use.
>  
Please go through this pastebin link, at my end, omap3_wdt_reset() happens at regular intervals, where ever
it is triggered. (print messages are inserted in omap3_wdt_reset)
https://pastebin.ubuntu.com/p/WvS9PZb45p/

The target doesn't restart.

Thanks
Suniel