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From:   Chen-Yu Tsai <wenst@chromium.org>
Date:   Wed, 6 Dec 2023 10:55:44 +0800
Message-ID: <CAGXv+5G5fFTv8zn=YamSdccjuYemE5oKBqjb8CSyGzu9aMJ0eg@mail.gmail.com>
Subject: Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark
 touchscreens and trackpads as fail
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Cc:     Doug Anderson <dianders@chromium.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Wolfram Sang <wsa@kernel.org>,
        Benson Leung <bleung@chromium.org>,
        Tzung-Bi Shih <tzungbi@kernel.org>,
        chrome-platform@lists.linux.dev, devicetree@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        Johan Hovold <johan@kernel.org>,
        Hsin-Yi Wang <hsinyi@chromium.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        andriy.shevchenko@linux.intel.com, Jiri Kosina <jikos@kernel.org>,
        linus.walleij@linaro.org, broonie@kernel.org,
        gregkh@linuxfoundation.org, hdegoede@redhat.com,
        james.clark@arm.com, james@equiv.tech, keescook@chromium.org,
        rafael@kernel.org, tglx@linutronix.de,
        Jeff LaBundy <jeff@labundy.com>, linux-input@vger.kernel.org,
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On Tue, Dec 5, 2023 at 6:22=E2=80=AFPM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> Il 04/12/23 17:50, Doug Anderson ha scritto:
> > Hi,
> >
> > On Sun, Dec 3, 2023 at 10:59=E2=80=AFPM Chen-Yu Tsai <wenst@chromium.or=
g> wrote:
> >>
> >> On Sat, Dec 2, 2023 at 8:58=E2=80=AFAM Doug Anderson <dianders@chromiu=
m.org> wrote:
> >>>
> >>> Hi,
> >>>
> >>> On Tue, Nov 28, 2023 at 12:45=E2=80=AFAM Chen-Yu Tsai <wenst@chromium=
.org> wrote:
> >>>>
> >>>> @@ -44,6 +46,7 @@ trackpad2: trackpad@2c {
> >>>>                  reg =3D <0x2c>;
> >>>>                  hid-descr-addr =3D <0x0020>;
> >>>>                  wakeup-source;
> >>>> +               status =3D "fail-needs-probe";
> >>>
> >>> While doing this, you could also remove the hack where the trackpad
> >>> IRQ pinctrl is listed under i2c4.
> >>
> >> Sure. I do think we can do away with it though. According to at least =
one
> >> schematic, the interrupt line has pull-ups on both sides of the voltag=
e
> >> shifter.
> >>
> >> BTW, The touchscreen doesn't have pinctrl entries. This has pull-ups o=
n
> >> both sides of the voltage shifter as well.
> >
> > I dunno if the convention is different on Mediatek boards, but at
> > least on boards I've been involved with in the past we've always put
> > pinctrl entries just to make things explicit. This meant that we
> > didn't rely on the firmware/bootrom/defaults to leave pulls in any
> > particular state. ...otherwise those external pull-ups could be
> > fighting with internal pull-downs, right?
> >
>
> MediaTek boards aren't special and there's no good reason for those to re=
ly on
> firmware/bootrom/defaults - so there is no good reason to avoid declaring=
 any
> relevant pinctrl entry.

I think this should be migrated to use the proper GPIO bindings: the
GPIO_PULL_UP / GPIO_PULL_DOWN / GPIO_BIAS_DISABLE flags.

But that's a different discussion.

ChenYu