[PATCH v2 0/5] I2C framework, reboot Unmatched via PMIC

[Jessica Clarke]

On 15 Oct 2021, at 15:05, Nikita Shubin <nikita.shubin at maquefel.me> wrote:
> 
> On Fri, 15 Oct 2021 14:56:40 +0100
> Jessica Clarke <jrtc27 at jrtc27.com> wrote:
> 
> Hello Jessica,
> 
>> The chip is common for RTC, power management and watchdog
>> functionality. Using it to reboot in this manner is not, as evidenced
>> by the fact that Linux does not have a driver for doing so and the
>> hardware vendor is unsure of how it’s even working the way it is. I
>> hope this driver is never needed for future RISC-V hardware (and I
>> don’t quite understand how it ended up being needed for the Unmatched,
>> when the Unleashed had a gpio-restart device, though that lacked a
>> gpio-poweroff I believe; seems like a very strange oversight).
>> 
>> Jess
>> 
> 
> Implementing SBC reset via Watchdog or PMIC is quite a common practice.

This sequence differs from the existing watchdog-based implementation
though, and to quote one of Dialog’s own engineers on LKML:

> Personally, if it was possible I think the RTC approach would be best as it's a
> full reset and to me is far safer with regards to potential side effects, but as
> that's not on the table then this seems the only other approach in your case.


This is why I am suggesting it not be a generic device tree thing, as
the vendor is basically saying it’s not a good option but the only
choice you have, so should be kept a quirk.

Jess