Re: [PATCH v1 1/1] pinctrl: add pinctrl/GPIO driver for Apple SoCs

From: Linus Walleij <linus.walleij@linaro.org>
To: Joey Gouly <joey.gouly@arm.com>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
	Andy Shevchenko <andriy.shevchenko@intel.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Hector Martin <marcan@marcan.st>, Marc Zyngier <maz@kernel.org>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
	Sven Peter <sven@svenpeter.dev>, nd <nd@arm.com>,
	Stan Skowronek <stan@corellium.com>
Subject: Re: [PATCH v1 1/1] pinctrl: add pinctrl/GPIO driver for Apple SoCs
Date: Tue, 28 Sep 2021 23:50:52 +0200	[thread overview]
Message-ID: <CACRpkdZJepfZ4WpWoUyKO_OyoibAVOaisLm-ADaLq8a0H2fWVQ@mail.gmail.com> (raw)
In-Reply-To: <20210928182114.GA19131@e124191.cambridge.arm.com>

On Tue, Sep 28, 2021 at 8:21 PM Joey Gouly <joey.gouly@arm.com> wrote:

> > > Linus? Do we really need this?
> >
> > I don't really see this as necessary, we don't need to check everything.
> > Not that it hurts either, so I would say maintainer preference?
> >
> I'm unsure if that means you (Linus), or Hector Martin as I put this
> file under the "ARM/APPLE MACHINE SUPPORT" section in MAINTAINERS.

Your preference, I am sure that even if Hector certainly may want to
chime in, he expects the code author (you) to assume a bit of
ownership of this piece of code for the foreseeable future,
so do what you consider reasonable.

> > I think npins should be known from the compatible (we know that
> > this version of the SoC has so and so many pins) and the base
> > should always be 0? It's not like we have several pin controllers
> > of this type in the SoC is it?
>
> All we need is the number of GPIOs from the DT now.
> I got a bit confused with the 'base' here, locally I have removed the
> 'pin_base' variable and usage. I was confusing it with the `gpio_chip.base` field,
> however that seems to be about the internal GPIO numbering.

The GPIO bindings have a standardized "ngpios" property that
indicates if you use less than the HW max number of GPIO
lines (roughly).

This is about pins rather, so something custom like
apple,npins = <...>;
could be used in that case.

Yours,
Linus Walleij