From mboxrd@z Thu Jan  1 00:00:00 1970
From: Geert Uytterhoeven <geert@linux-m68k.org>
Subject: Re: [PATCH v3 3/8] gpio: gpio-rz: GPIO driver for Renesas RZ series
Date: Thu, 19 Jan 2017 10:36:21 +0100
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To: Linus Walleij <linus.walleij@linaro.org>
Cc: Jacopo Mondi <jacopo+renesas@jmondi.org>, Magnus Damm <magnus.damm@gmail.com>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Geert Uytterhoeven <geert+renesas@glider.be>, Chris Brandt <chris.brandt@renesas.com>, Linux-Renesas <linux-renesas-soc@vger.kernel.org>, "linux-gpio@vger.kernel.org" <linux-gpio@vger.kernel.org>
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Hi Linus,

On Thu, Jan 19, 2017 at 10:27 AM, Linus Walleij
<linus.walleij@linaro.org> wrote:
> On Wed, Jan 18, 2017 at 3:06 PM, Geert Uytterhoeven
> <geert@linux-m68k.org> wrote:
>> On Wed, Jan 18, 2017 at 2:58 PM, Linus Walleij <linus.walleij@linaro.org> wrote:
>>>> +       gpio_chip->request = rz_gpio_request;
>>>> +       gpio_chip->free = rz_gpio_free;
>>>> +       gpio_chip->label = dev_name(&pdev->dev);
>>>> +       gpio_chip->parent = &pdev->dev;
>>>> +       gpio_chip->owner = THIS_MODULE;
>>>> +       gpio_chip->base = -1;
>>>> +       gpio_chip->ngpio = ret == 0 ? args.args[2] : RZ_GPIOS_PER_PORT;
>>>
>>> bgpio_init() will have already set this up to 16 (RZ_GPIOS_PER_PORT)
>>> as we pass width 2 bytes.
>>
>> Note that some banks have less than 16 GPIOs, cfr. the last value of the
>> gpio-ranges tuple being less than 16.
>
> Aha OK then it is fine to override this default value calculate from
> the register size.
>
> But for that case we should use the standard DT property
> ngpios described in
> Documentation/devicetree/bindings/gpio/gpio.txt
> It is for exactly this purpose.

IC.

Note that gpio-rcar uses the same method, switching to "ngpios" would
break backwards compatibility.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds