[U-Boot] OMAP watchdog timer reset on BBB

Stefan Roese sr at denx.de
Fri Sep 13 11:20:07 UTC 2019

Hi Sam,

On 12.09.19 18:33, 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?

If the board has CONFIG_WATCHDOG enabled, then it should call the
reset function periodically (omap3_wdt_reset). Please check if
this function get called - I assume pretty often.

If it gets called and a WDT reset still does occur after the
timeout, then the reset function is incorrect and does not reset
the watchdog timer correctly.



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