linux-kernel - Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail

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Date:   Mon, 4 Dec 2023 08:50:01 -0800
From:   Doug Anderson <dianders@...omium.org>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Wolfram Sang <wsa@...nel.org>,
        Benson Leung <bleung@...omium.org>,
        Tzung-Bi Shih <tzungbi@...nel.org>,
        chrome-platform@...ts.linux.dev, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Johan Hovold <johan@...nel.org>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        andriy.shevchenko@...ux.intel.com, Jiri Kosina <jikos@...nel.org>,
        linus.walleij@...aro.org, broonie@...nel.org,
        gregkh@...uxfoundation.org, hdegoede@...hat.com,
        james.clark@....com, james@...iv.tech, keescook@...omium.org,
        rafael@...nel.org, tglx@...utronix.de,
        Jeff LaBundy <jeff@...undy.com>, linux-input@...r.kernel.org,
        linux-i2c@...r.kernel.org
Subject: Re: [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark
 touchscreens and trackpads as fail

Hi,

On Sun, Dec 3, 2023 at 10:59 PM Chen-Yu Tsai <wenst@...omium.org> wrote:
>
> On Sat, Dec 2, 2023 at 8:58 AM Doug Anderson <dianders@...omium.org> wrote:
> >
> > Hi,
> >
> > On Tue, Nov 28, 2023 at 12:45 AM Chen-Yu Tsai <wenst@...omium.org> wrote:
> > >
> > > @@ -44,6 +46,7 @@ trackpad2: trackpad@2c {
> > >                 reg = <0x2c>;
> > >                 hid-descr-addr = <0x0020>;
> > >                 wakeup-source;
> > > +               status = "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 voltage
> shifter.
>
> BTW, The touchscreen doesn't have pinctrl entries. This has pull-ups on
> 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?

-Doug