linux-kernel - Re: [PATCH v9 2/4] pinctrl: pinmux: Add pinmux-select debugfs file

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Message-ID: <CACRpkda=_qSY04mjyYUt1ox_yGgmTR3YPRrOYeJeMLjvba0ADA@mail.gmail.com>
Date:   Mon, 15 Mar 2021 17:24:21 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     "Enrico Weigelt, metux IT consult" <lkml@...ux.net>
Cc:     Drew Fustini <drew@...gleboard.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Jason Kridner <jkridner@...gleboard.org>,
        Robert Nelson <robertcnelson@...gleboard.org>,
        Joe Perches <joe@...ches.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Jonathan Corbet <corbet@....net>,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: Re: [PATCH v9 2/4] pinctrl: pinmux: Add pinmux-select debugfs file

On Fri, Mar 12, 2021 at 2:57 PM Enrico Weigelt, metux IT consult
<lkml@...ux.net> wrote:
> On 02.03.21 06:30, Drew Fustini wrote:
>
> Hi folks,
>
> > Add "pinmux-select" to debugfs which will activate a pin function for a
> > given pin group:
> >
> >    echo "<group-name function-name>" > pinmux-select
> >
> > The write operation pinmux_select() handles this by checking that the
> > names map to valid selectors and then calling ops->set_mux().
>
> I've already been playing with similar idea, but for external muxes.
> For example, some boards have multiple SIM slots that can be switched
> via some gpio pin.
>
> Not sure whether traditional pinmux would be a good match for that.

What is wrong with the subsystem
drivers/mux?

It's exactly for this usecase I think. Peter Rosin already wrote
a GPIO-controlled mux driver too.

Yours,
Linus Walleij