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

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Message-ID: <eab4ef1e-f63f-4561-b429-6dc3d7485871@collabora.com>
Date: Tue, 8 Oct 2024 10:47:49 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Chen-Yu Tsai <wenst@...omium.org>,
 Matthias Brugger <matthias.bgg@...il.com>
Cc: 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

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.

Cheers,
Angelo

> +		vdd-supply = <&mt6397_vgp6_reg>;
>   		wakeup-source;
>   	};
>   };