linux-kernel - Re: [PATCH] pinctrl: lochnagar: select GPIOLIB

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Message-ID: <322b5fbe-e9ca-99cd-80d0-000a5464b37a@opensource.cirrus.com>
Date:   Tue, 7 Jan 2020 11:58:22 +0000
From:   Richard Fitzgerald <rf@...nsource.cirrus.com>
To:     Arnd Bergmann <arnd@...db.de>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     Charles Keepax <ckeepax@...nsource.cirrus.com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@...a-project.org>, <patches@...nsource.cirrus.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pinctrl: lochnagar: select GPIOLIB

On 07/01/2020 10:39, Arnd Bergmann wrote:
> On Tue, Jan 7, 2020 at 10:45 AM Linus Walleij <linus.walleij@...aro.org> wrote:
>> On Wed, Dec 18, 2019 at 5:37 PM Arnd Bergmann <arnd@...db.de> wrote:
>>> I wonder if GPIOLIB should just become mandatory when enabling the pinctrl
>>> subsystem, or if there are still good reasons for leaving it disabled
>>> on any machine that uses CONFIG_PINCTRL.
>>
>> Hm that is a tricky question, they almost always come in pair but are
>> technically speaking separate subsystems.
> 
> I think there are a number of use cases for GPIOLIB drivers without PINCTRL, but
> are there any examples of the reverse?
> 
>         Arnd
> 

You could have muxable pins that aren't gpios. For example muxing 
between i2c/spi signals. So a pinctrl driver doesn't imply gpio.