linux-kernel - Re: [PATCH 1/3] gpio / ACPI: Drop unnecessary ACPI GPIO to Linux GPIO translation

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Message-ID: <CAJZ5v0jkzMvKfLnDgNa9-dsHLC_7g6Y57kmO_Qzr1wfL13rX_A@mail.gmail.com>
Date:   Tue, 28 Nov 2017 22:05:45 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Hans de Goede <hdegoede@...hat.com>,
        Takashi Iwai <tiwai@...e.de>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] gpio / ACPI: Drop unnecessary ACPI GPIO to Linux GPIO translation

On Mon, Nov 27, 2017 at 2:54 PM, Mika Westerberg
<mika.westerberg@...ux.intel.com> wrote:
> We added acpi_gpiochip_pin_to_gpio_offset() because there was a need to
> translate from ACPI GpioIo/GpioInt number to Linux GPIO number in the
> Cherryview pinctrl driver. This translation is necessary because
> Cherryview has gaps in the pin list and the driver used continuous GPIO
> number space in Linux side as follows:
>
>   created GPIO range 0->7 ==> INT33FF:03 PIN 0->7
>   created GPIO range 8->19 ==> INT33FF:03 PIN 15->26
>   created GPIO range 20->25 ==> INT33FF:03 PIN 30->35
>   created GPIO range 26->33 ==> INT33FF:03 PIN 45->52
>   created GPIO range 34->43 ==> INT33FF:03 PIN 60->69
>   created GPIO range 44->54 ==> INT33FF:03 PIN 75->85
>
> For example when ACPI GpioInt resource refers to GPIO 81 (SDMMC3_CD_B)
> we translate from pin 81 to the corresponding Linux GPIO number, which
> is 50. This number is then used when the GPIO is accessed through gpiolib.
>
> It turns out, this is not necessary at all. We can just pass 1:1 mapping
> between Linux GPIO numbers and pin numbers (including gaps) and the
> pinctrl core handles all the details automatically:
>
>   created GPIO range 0->7 ==> INT33FF:03 PIN 0->7
>   created GPIO range 15->26 ==> INT33FF:03 PIN 15->26
>   created GPIO range 30->35 ==> INT33FF:03 PIN 30->35
>   created GPIO range 45->52 ==> INT33FF:03 PIN 45->52
>   created GPIO range 60->69 ==> INT33FF:03 PIN 60->69
>   created GPIO range 75->85 ==> INT33FF:03 PIN 75->85
>
> Here GPIO 81 is exactly same than the hardware pin 81 (SDMMC3_CD_B).
>
> As an added bonus this simplifies both the ACPI GPIO core code and the
> Cherryview pinctrl driver.

Cool!

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>