linux-kernel - Re: [PATCH] arm64: dts: mediatek: mt8173-elm-hana: Add vdd-supply to second source trackpad

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Message-ID: <CAGXv+5Emb5b5m8i3MCJXS3fRND04B89v9s1x7JNk4aNj6U7yoA@mail.gmail.com>
Date: Tue, 8 Oct 2024 18:19:18 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: Matthias Brugger <matthias.bgg@...il.com>, devicetree@...r.kernel.org, 
	linux-mediatek@...ts.infradead.org, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: mediatek: mt8173-elm-hana: Add vdd-supply to
 second source trackpad

On Tue, Oct 8, 2024 at 4:47 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> wrote:
>
> Il 08/10/24 10:20, Chen-Yu Tsai ha scritto:
> > The Hana device has a second source option trackpad, but it is missing
> > its regulator supply. It only works because the regulator is marked as
> > always-on.
> >
> > Add the regulator supply, and the required post-power-on delay.
> >
> > Fixes: 689b937bedde ("arm64: dts: mediatek: add mt8173 elm and hana board")
> > Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> > ---
> >   arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi b/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
> > index 8d1cbc92bce3..e03474702cad 100644
> > --- a/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
> > +++ b/arch/arm64/boot/dts/mediatek/mt8173-elm-hana.dtsi
> > @@ -49,6 +49,12 @@ trackpad2: trackpad@2c {
> >               interrupts-extended = <&pio 117 IRQ_TYPE_LEVEL_LOW>;
> >               reg = <0x2c>;
> >               hid-descr-addr = <0x0020>;
> > +             /*
> > +              * The supply is always on. Adding the delay here
> > +              * needlessly delays the readiness of the trackpad.
>
> I'd say, let's be nice in this comment and let's explain the whole situation:
>
> The trackpad needs a post power on delay of 100ms but, at the time
> of writing, the power supply for it on this board is set as always-on,
> so we don't add that to avoid useless delays in the readiness of this device.
>
>
> ...or....
>
> The trackpad needs a post power on delay of 100ms but the power supply for
> it on this board is always-on (and will always be), so we don't add delays
> to avoid impacting on the time required for readiness of this device.
>
> > +              */
> > +             /* post-power-on-delay-ms = <100>; */
>
> Then you can remove this commented out property ;-)
>
> P.S.: Just to be clear, what I dislike is to see a property that is commented out.

Got it. Will rewrite. :D

ChenYu