linux-kernel - Re: [PATCH] pinctrl: core: print gpio in pins debugfs file

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Date:   Mon, 20 Jul 2020 16:26:21 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Drew Fustini <drew@...gleboard.org>
Cc:     Andy Shevchenko <andy.shevchenko@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Linux-OMAP <linux-omap@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jason Kridner <jkridner@...gleboard.org>,
        Robert Nelson <robertcnelson@...il.com>
Subject: Re: [PATCH] pinctrl: core: print gpio in pins debugfs file

Hi Drew,

thanks for this patch, we're going the right direction here
and creating things that are generically useful.

On Sat, Jul 18, 2020 at 5:53 PM Drew Fustini <drew@...gleboard.org> wrote:

> pin 103 (PIN103) GPIO-113 44e1099c 00000027 pinctrl-single
> pin 104 (PIN104) GPIO-114 44e109a0 0000002c pinctrl-single
(...)

Uh oh, that is the global GPIO number that we want to get
rid of.

> +               gpio_num = 0;
> +               list_for_each_entry(range, &pctldev->gpio_ranges, node) {
> +                       if ((pin >= range->pin_base) &&
> +                           (pin < (range->pin_base + range->npins)))
> +                               gpio_num = range->base + (pin - range->pin_base);

There should be a break; here should it not?

> +               }
> +
> +               if (gpio_num > 0)
> +                       seq_printf(s, "GPIO-%u ", gpio_num);

Can we print the gpio_chip name and offset instead?
I want to discourage the world from thinking about these
global GPIO numbers.

You can fetch the gpio_chip for the range pretty easily
with

struct gpio_chip *chip = gpio_to_chip(gpio_num);

Also notice that this code needs to be
#ifdef CONFIG_GPIOLIB somehow
(maybe IS_ENABLED() works) because there
are pin controllers in use without gpiolib believe it
or not.

Yours,
Linus Walleij