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

[Drew Fustini <drew@xxxxxxxxxxxxxxx>]

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