Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.35 as permitted sender) client-ip=23.128.96.35;
MIME-Version: 1.0
References: <20230913115001.23183-1-brgl@bgdev.pl> <20230913115001.23183-4-brgl@bgdev.pl>
 <CACRpkdax-CrB42LeQ1bs3E7VqMncsgEwMs7b_v7J6R5AE+BjAg@mail.gmail.com>
In-Reply-To: <CACRpkdax-CrB42LeQ1bs3E7VqMncsgEwMs7b_v7J6R5AE+BjAg@mail.gmail.com>
From:   Bartosz Golaszewski <brgl@bgdev.pl>
Date:   Wed, 13 Sep 2023 14:39:21 +0200
Message-ID: <CAMRc=Mdt0wbjzbwBLK5m--VLV2WE5JybgrNYWXtbinPu_c=psw@mail.gmail.com>
Subject: Re: [PATCH 3/5] mmc: slot-gpio: use gpiod_set_active_[low|high]()
To:     Linus Walleij <linus.walleij@linaro.org>
Cc:     Andy Shevchenko <andy@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Paul Cercueil <paul@crapouillou.net>,
        Harvey Hunt <harveyhuntnexus@gmail.com>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Daniel Scally <djrscally@gmail.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <markgross@kernel.org>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-mmc@vger.kernel.org, linux-mips@vger.kernel.org,
        linux-mtd@lists.infradead.org, platform-driver-x86@vger.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, Sep 13, 2023 at 2:24=E2=80=AFPM Linus Walleij <linus.walleij@linaro=
.org> wrote:
>
> On Wed, Sep 13, 2023 at 1:50=E2=80=AFPM Bartosz Golaszewski <brgl@bgdev.p=
l> wrote:
>
> > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> >
> > We have new, less cumbersome and clearer interfaces for controlling GPI=
O
> > polarity. Use them in the MMC code.
> >
> > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> I like the looks of the code better, obviously but this looks like this f=
or
> a reason unfortunately.
>
> See the following from
> Documentation/devicetree/bindings/mmc/mmc-controller.yaml:
>
>   # CD and WP lines can be implemented on the hardware in one of two
>   # ways: as GPIOs, specified in cd-gpios and wp-gpios properties, or
>   # as dedicated pins. Polarity of dedicated pins can be specified,
>   # using *-inverted properties. GPIO polarity can also be specified
>   # using the GPIO_ACTIVE_LOW flag. This creates an ambiguity in the
>   # latter case. We choose to use the XOR logic for GPIO CD and WP
>   # lines.  This means, the two properties are "superimposed," for
>   # example leaving the GPIO_ACTIVE_LOW flag clear and specifying the
>   # respective *-inverted property property results in a
>   # double-inversion and actually means the "normal" line polarity is
>   # in effect.
>

I hate it, thanks. :)

> Will you still provide the desired "double inversion" after this patch?
>

Not in the current form. Would it work to go:

if (override_active_level) {
    if (!(host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH))
        gpiod_set_active_high(desc);
    else
        gpiod_set_active_low(desc);
} else {
    if (host->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
        gpiod_set_active_high(desc);
    else
        gpiod_set_active_low(desc);
}

?

Alternatively we could reimplement the toggle semantics locally in a
helper function in order to get rid of it from GPIOLIB.

Bart