linux-kernel - Re: [PATCH v2 2/4] Documentation: DT: bindings: input: Add documentation for cyttsp5

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Date:   Thu, 18 Nov 2021 22:51:41 +1000
From:   Alistair Francis <alistair23@...il.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Andreas Kemnade <andreas@...nade.info>,
        Alistair Francis <alistair@...stair23.me>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-input <linux-input@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Mylene Josserand <mylene.josserand@...e-electrons.com>,
        Henrik Rydberg <rydberg@...math.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v2 2/4] Documentation: DT: bindings: input: Add
 documentation for cyttsp5

On Fri, Nov 12, 2021 at 1:16 AM Linus Walleij <linus.walleij@...aro.org> wrote:
>
> On Wed, Nov 10, 2021 at 6:37 PM Andreas Kemnade <andreas@...nade.info> wrote:
> > Alistair Francis <alistair23@...il.com> wrote:
>
> > You have a kind of double inversion here, so things are automagically fixed.
> > IMHO to describe it correctly would be to set GPIO_ACTIVE_LOW here
> > and in the driver
> >
> >         /* Reset the gpio to be in a reset state */
> >         ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
> >         if (IS_ERR(ts->reset_gpio)) {
> >                 rc = PTR_ERR(ts->reset_gpio);
> >                 dev_err(dev, "Failed to request reset gpio, error %d\n", rc);
> >                 return rc;
> >         }
> >         gpiod_set_value(ts->reset_gpio, 0);
> >
> > That is the way how other active-low reset lines are handled.
>
> Correct.
>
> This is a source of confusion, I contemplated just changing the name
> of GPIOD_OUT_HIGH to GPIOD_OUT_ASSERTED etc to indicate
> what is going on.
>
> gpiod_set_value(ts->reset_gpio, 0) should similarly be interpreted
> as "de-assert this line" no matter the polarity.

Thanks! I have fixed this

Alistair

>
> Yours,
> Linus Walleij