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Date:   Sat, 13 Mar 2021 00:42:39 -0800
From:   Drew Fustini <drew@beagleboard.org>
To:     "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
        Tony Lindgren <tony@atomide.com>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Alexandre Belloni <alexandre.belloni@bootlin.com>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
        Jason Kridner <jkridner@beagleboard.org>,
        Robert Nelson <robertcnelson@beagleboard.org>,
        Joe Perches <joe@perches.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Jonathan Corbet <corbet@lwn.net>, linux-doc@vger.kernel.org,
        Geert Uytterhoeven <geert+renesas@glider.be>
Subject: Re: [PATCH v9 2/4] pinctrl: pinmux: Add pinmux-select debugfs file
Message-ID: <20210313084239.GB1172642@x1>
References: <20210302053059.1049035-1-drew@beagleboard.org>
 <20210302053059.1049035-3-drew@beagleboard.org>
 <349b09f8-fe99-d0d4-dd11-c288bf66cb4d@metux.net>
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On Fri, Mar 12, 2021 at 02:57:54PM +0100, Enrico Weigelt, metux IT consult 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.
> 
> 
> --mtx
> 

Thank you for your comment.  I am interested in understanding other
use cases.

Linus can hopefully correct me, but I think this is covered by section
"Drivers needing both pin control and GPIOs" in pinctl.rst [1]. The
driver could be both a GPIO consumer and pinctrl consumer and then be
able to call pinctrl_select_state() and devm_gpio_request().

Thank you,
Drew

[1] https://www.kernel.org/doc/html/latest/driver-api/pinctl.html