linux-kernel - Re: [PATCH] gpiolib: TODO: add an item about GPIO safe-state

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Date:   Wed, 14 Sep 2022 17:22:35 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Kent Gibson <warthog618@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Drew Fustini <dfustini@...libre.com>,
        Marek Vasut <marek.vasut@...il.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpiolib: TODO: add an item about GPIO safe-state

On Wed, Sep 14, 2022 at 5:20 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Bartosz,
>
> On Wed, Sep 14, 2022 at 4:11 PM Bartosz Golaszewski <brgl@...ev.pl> wrote:
> > This adds a new TODO item for gpiolib and can also be used to start
> > a discussion about the need for it and implementation details.
> >
> > Signed-off-by: Bartosz Golaszewski <brgl@...ev.pl>
>
> > --- a/drivers/gpio/TODO
> > +++ b/drivers/gpio/TODO
>
> > +This item is about proposing a solution, most likely in the form of a new device
> > +property called "safe-state" that would define the safe states of specific lines
> > +(e.g. output-high) but not block the line from being requested by users who
> > +could then modify that default state. Once released the GPIO core would then
> > +put the line back into the "safe-state".
>
> #bikeshedding
>
> If this state is the "safe" state, would that imply that any other state is
> "unsafe"? I guess not, as the idea is that a knowledgeable driver can
> still change it (else a hog would be sufficient).
> Hence I think "idle-state" would reflect this better. Any other thoughts?
>

No, you're right, you even mentioned the name "idle-state" during the
BoF session.

Bart