[PATCH v3 2/4] watchdog: da9062: reset board on watchdog timeout

[Christoph Niedermaier]

From: Andrej Picej [mailto:andrej.picej at norik.com]
Sent: Thursday, December 2, 2021 8:43 AM

[...]
>> I have a question how to correctly restart the system after
>> watchdog timeout.
>> If I understand it correct after watchdog timeout the system
>> restarts only if WATCHDOG_SD (Bit 3) in register CONFIG_I is
>> set.
>> What is the difference if WATCHDOG_SD isn't set, but WAKE_UP
>> (Bit 2) in register CONTROL_F is set? From outside on my
>> system I observe the same behavior. After watchdog timeout
>> my system restarts. So where are the differences?
>> It would be nice if you could answer this question, as you
>> certainly know this chip very well.
> 
> To be honest I don't really know the chip that well, I'm just trying to
> add this feature and hopefully help others if they run into the same
> problem. I think @Adam will be more helpful here.
> 
> But from quick look at da9062 datasheet, mainly chapter "8.8 Power
> Modes" I see next main differences:
> - setting WATCHDOG_SD enables SHUTDOWN sequence when the watchdog
> timeout is triggered. This puts the chip (da9062) in RESET mode.
> Taken from DA9062 datasheet:
> > In RESET mode, the internal supplies, and LDO1 (if configured as an
> always-on supply) are enabled.
> > All other DA9062 supplies are disabled.
> > DA9062 is in RESET mode whenever a complete application shutdown is
> required
> > The DA9062’s register configuration will be re-loaded from OTP when
> leaving the RESET mode
> 
> - if you set the WAKE_UP bit than the chip enters POWERDOWN mode on
> watchdog timeout. I understand the POWERDOWN mode as a not that "deep"
> mode as a RESET mode Device will go from RESET mode to POWERDOWN mode in
> the sequence of powering-up.
> 
> The above explanation is just my understanding after quick look, @Adam
> please correct me if I'm talking nonsense.
> 
> Please have a look at the DA9062 datasheet for more information. Sorry,
> that I can't be more helpful here.


Hi Andrej,

Thanks a lot for your explanation. 
I think I would like to test your implementation, because this seems
to be the better way to restart the system to a reliable state.
I have a DA9061 which supplies an i.MX6ULL.
Would you be so kind to adapt your patch 1/4 for the DA9061?
For details I will also answer on your patch 1/4.

Thanks and regards
Christoph