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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Fri, 2 Sep 2022 13:52:37 +0300
Message-ID: <CAHp75VfF78rWpC6+i2Hu6-PMULFeFMbqXhBVRkx5aFGFTU3U4A@mail.gmail.com>
Subject: Re: [PATCH v1 4/8] gpiolib: Get rid of ARCH_NR_GPIOS
To:     Arnd Bergmann <arnd@arndb.de>,
        =?UTF-8?B?TnVubyBTw6E=?= <nuno.sa@analog.com>
Cc:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Keerthy <j-keerthy@ti.com>, Russell King <linux@armlinux.org.uk>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        Linux-Arch <linux-arch@vger.kernel.org>,
        Linux Documentation List <linux-doc@vger.kernel.org>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>
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Precedence: bulk

(Nuno, one point below for you)

On Wed, Aug 31, 2022 at 11:55 PM Arnd Bergmann <arnd@arndb.de> wrote:

...

> drivers/gpio/gpio-adp5520.c:    gc->base = pdata->gpio_start; // unused
> drivers/gpio/gpio-adp5588.c:            gc->base = pdata->gpio_start; // unused
> drivers/input/keyboard/adp5588-keys.c:  kpad->gc.base = gpio_data->gpio_start; // unused
> drivers/input/keyboard/adp5589-keys.c:  kpad->gc.base = gpio_data->gpio_start; // unused

I believe we should convert them to -1.

> drivers/gpio/gpio-bt8xx.c:      c->base = modparam_gpiobase; // from modprobe
> drivers/gpio/gpio-ich.c:        chip->base = modparam_gpiobase; // from modprobe

I believe it was designed for Intel hardware and so it can't be higher
than 512 - ngpios, where the latter one is small enough (dozen or a
couple of dozens of pins).

> drivers/gpio/gpio-dwapb.c:      port->gc.base = pp->gpio_base; // from DT, deprecated

From board files, since some platforms expect a fixed number for it.

> drivers/gpio/gpio-mockup.c:     gc->base = base; // module parama

This is for testing, so the test cases should be amended accordingly.
But I think the module itself is deprecated, and gpio-sim seems not
using it as a modprobe parameter, but rather as configfs.

> drivers/gpio/gpio-pca953x.c:    gc->base = chip->gpio_start; // ???? used a lot

To answer this one needs to go via all board files (most of them ARM
32-bit based) and look, but it means almost the same case as per Intel
above: 512-ngpios.

> drivers/pinctrl/renesas/gpio.c: gc->base = pfc->nr_gpio_pins; // ??? don't understand

I think, w/o looking into the code, that this just guarantees the
continuous numbering for all banks (chips) on the platform.

> drivers/pinctrl/stm32/pinctrl-stm32.c:          bank->gpio_chip.base = args.args[1];

Device Tree?!

-- 
With Best Regards,
Andy Shevchenko