Re: [PATCH v11 2/8] mfd: bd70528: Support ROHM bd70528 PMIC - core

[Alexandre Belloni]

On 04/04/2019 10:24:49+0300, Matti Vaittinen wrote:
> On Thu, Apr 04, 2019 at 07:54:52AM +0100, Lee Jones wrote:
> > On Thu, 04 Apr 2019, Vaittinen, Matti wrote:
> > 
> > > Actually, now that I thik of it the right way to do this would have
> > > been the function pointer in parent data as was done in original patch
> > > set. HW-colleagues tend to re-use HW blocks, and we like to re-use our
> > > drivers. If the next PMIC from ROHM uses same RTC block but does not
> > > provide watchdog - then it is cleanest solution to fall back to
> > > function pointer and leave it to NULL when there is no WDT or when WDT
> > > is unused. Another option is to export dummy function - which is not so
> > > nice.
> > 
> > I think the converse is true.
> > 
> > Pointers to functions outside of a subsystem API context are generally
> > horrible.  It's much nicer to call a function which can be easily
> > stubbed out in a header file based on a Kconfig option.  It's how most
> > kernel APIs work.
> 
> I hate to admit but I see your point. This nicely solves any issues in
> syncronizing the startup for driver providing function pointer and for
> driver using it.
> 

Wouldn't it be easier to register the watchdog driver as part of the RTC
driver?

As I see it, the wdt is just a glorified RTC alarm.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com