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From:   Linus Walleij <linus.walleij@linaro.org>
Date:   Fri, 26 Aug 2022 23:54:22 +0200
Message-ID: <CACRpkdZpwdP+1VitohznqRfhFGcLT2f+sQnmsRWwMBB3bobwAw@mail.gmail.com>
Subject: Re: [PATCH] gpio: Allow user to customise maximum number of GPIOs
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Alexandre Courbot <gnurou@gmail.com>,
        Alexandre Courbot <acourbot@nvidia.com>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        Jonathan Corbet <corbet@lwn.net>,
        Russell King <linux@armlinux.org.uk>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
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        open list <linux-kernel@vger.kernel.org>,
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On Fri, Aug 26, 2022 at 5:08 PM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
> Le 26/08/2022 =C3=A0 15:49, Linus Walleij a =C3=A9crit :
> > On Thu, Aug 25, 2022 at 4:00 PM Christophe Leroy
> > <christophe.leroy@csgroup.eu> wrote:
> >
> >>> Christophe? Will you take a stab at it?
> >>
> >> Which patch should I write ?
> >
> > One that removes CONFIG_ARCH_HAS_NR_GPIO entirely, then
> > allocate bases for new GPIO chips from 0 and upward instead.
> > And then see what happens.
> >
>
> Ok, I can give it a try.

Nice!

> But what do I do with:
>
> drivers/gpio/gpio-aggregator.c: bitmap =3D bitmap_alloc(ARCH_NR_GPIOS,
> GFP_KERNEL);

That's just used locally in that driver to loop over the arguments to the
aggregator (from the file in sysfs). I would set some arbitrary root
like
#define AGGREGATOR_MAX_GPIOS 512
and just search/replace with that.

Yours,
Linus Walleij