Re: [PATCH] pinctrl: pinmux: Add pinmux-select debugfs file

[Drew Fustini <drew@beagleboard.org>]

On Fri, Jan 29, 2021 at 12:15:34PM +0200, Andy Shevchenko wrote:
> On Fri, Jan 29, 2021 at 10:49 AM Drew Fustini <drew@beagleboard.org> wrote:
> >
> > Add "pinmux-select" to debugfs which will activate a function and group
> > when 2 integers "<function-selector> <group-selector>" are written to
> > the file. The write operation pinmux_select() handles this by checking
> > if fsel and gsel are valid selectors and then calling ops->set_mux().
> >
> > The existing "pinmux-functions" debugfs file lists the pin functions
> > registered for the pin controller. For example:
> >
> > function: pinmux-uart0, groups = [ pinmux-uart0-pins ]
> > function: pinmux-mmc0, groups = [ pinmux-mmc0-pins ]
> > function: pinmux-mmc1, groups = [ pinmux-mmc1-pins ]
> > function: pinmux-i2c0, groups = [ pinmux-i2c0-pins ]
> > function: pinmux-i2c1, groups = [ pinmux-i2c1-pins ]
> > function: pinmux-spi1, groups = [ pinmux-spi1-pins ]
> >
> > To activate function pinmux-i2c1 (fsel 4) and group pinmux-i2c1-pins
> > (gsel 4):
> >
> > echo '4 4' > pinmux-select
> 
> Hmm... Where is the documentation? Where is the changelog? What is the
> version of this patch? What happened to my suggestion to have another
> (preparatory) patch to move to octal permissions? I'm completely
> confused.
> 
> Please, resend according to the rules.

Sorry for causing the confusion. I dropped the change long when moving
from RFC v2 to this PATCH.  But I can see how it is better to keep so
that people just looking at this for the first time have better context
for what happened in the RFC discussion.

I did post a patch this past Monday so switch all the debugfs files in
pinctrl subsystem over to octal permission [1]. But now I think that
this should have been series with this patch. Linus has not applied it
yet so I'll make a series when I send v2 of this patch.

Regarding the documentation, there is no existing documentation for any
of the debugfs enteries for pinctrl, so it seemed to have a bigger scope
than just this patch. I also noticed that rst documentation is
confusingly named "pinctl" (no 'r') and started a thread about that [2].
Linus suggested chaning that to 'pin-control'. Thus I am thinking about
a documentation patch series where the file is renamed, references
changed and a section on the debugfs files is added. Do that sound like
a reasonable approach?

Thank you,
Drew

[1] https://lore.kernel.org/linux-gpio/20210126044742.87602-1-drew@beagleboard.org/
[2] https://lore.kernel.org/linux-gpio/20210126050817.GA187797@x1/