[PATCH 2/3] watchdog: mtk_wdt: add support for 16-bit control registers

[Matthias Brugger]

On 02/02/2021 02:33, Boris Lysov wrote:
> В Sun, 31 Jan 2021 16:31:09 -0800
> Guenter Roeck <linux at roeck-us.net> пишет:
> 
>> We can't do this. With this flag enabled, the watchdog won't
>> support other SoCs, and there is nothing that prevents the flag
>> from being set for those SoCs.
>>
>> This has to be handled differently, without configuration
>> flag. Maybe use regmap for register addresses, [snip],
>> or use accessor functions in mtk_wdt_dev.
> 
> Thank you for reviewing my patch!
> 
> I will consider suggested fixes, and I will come up with better solution
> in V2. I'm beginner developer, and am still learning.
> 
>> use the compatible string to determine which regmap settings to use
> 
> I think relying on hardcoded "compatible string - settings" pairs in
> driver is not good. Whilst most Mediatek watchdogs I've seen use
> similar drivers, no one (except Mediatek itself, of course) knows for
> sure how many devices use 16-bit mode, and specifying each one in C
> code may _theoretically_ bloat it. (well, on the other hand, I've seen
> other watchdog drivers with many compatible devices listed in C code,
> and they didn't seem bloated at all)

We enable 16 bit access for "mediatek,mt6577-wdt" if we have a new SoC that also
needs 16 bit access, most probably we can just update the binding documentation
by adding the new SoC with a fallback to mt6577:

"mediatek,mt1234-wdt", "mediatek,mt6577-wdt": for MT1234

As no binding to mt1234 is present in the driver, the mt6577 one will be used.

Regards,
Matthias