Re: gpio-generic DT bindings?

[Tom Rini <trini-l0cyMroinI0@public.gmane.org>]

On Tue, Nov 19, 2013 at 03:38:20PM -0700, Stephen Warren wrote:
> On 11/19/2013 03:17 PM, Geert Uytterhoeven wrote:
> > On Tue, Nov 19, 2013 at 10:59 PM, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote:
> >> On 11/19/2013 02:45 PM, Geert Uytterhoeven wrote:
> >>> This topic seems to come up from time to time.
> >>> Unfortunately the last time it coincided with the move of the mailing list
> >>> from ozlabs to vger, causing the mailing list archives not to have captured
> >>> the full discussion.
> >>>
> >>> Is there anything definitive/usable out there?
> >>
> >> What do you mean by "gpio-generic DT bindings"? A generic binding for a
> >> controller, or something else? I think it's best to have a specific
> >> binding for each individual controller, so it's always possible to know
> >> exactly which controller is present. Now, all the binding definitions
> >> should all look the same or as similar as possible for consistency...
> > 
> > I mean DT bindings and DT support for drivers/gpio/gpio-generic.c.
> 
> We should have DT bindings for particular HW, not for a driver. After
> all, DT describes HW, not a particular OS's driver.
> 
> The path to adding DT support to gpio-generic.c is to define a binding
> for the particular HW you're interested in (which would quite likely
> only contain compatible, reg, and perhaps some other standard properties
> like interrupts, clocks, power domains, etc.). There would be one
> binding and compatible value for each different HW block you want to
> support, although they could all share the same schema and definition.
> Then update gpio-generic.c to bind to that (those) compatible value(s),
> and have some kind of table that maps from compatible value to whatever
> configuration structure gpio-generic.c uses internally.

This I think is the rub that Geert is getting at.  The driver is
generic.  You feed it a little info and it Just Works.  Having to patch
the generic driver N times for vendor,foo-gpio would be a step
backwards.  How do we have a binding here that lets us be as flexible as
we are today?

-- 
Tom
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