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From:   Doug Anderson <dianders@chromium.org>
Date:   Fri, 20 May 2022 13:38:15 -0700
Message-ID: <CAD=FV=VKqnTWDP9vkxhsR_QVj5rXNXNNwjTaQX431J1JQBTSqA@mail.gmail.com>
Subject: Re: [PATCH] arm64: dts: qcom: sc7280: Enable keyboard backlight for villager
To:     Matthias Kaehlcke <mka@chromium.org>
Cc:     Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>
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Hi,

On Fri, May 20, 2022 at 1:29 PM Matthias Kaehlcke <mka@chromium.org> wrote:
>
> On Fri, May 20, 2022 at 12:57:50PM -0700, Doug Anderson wrote:
> > Hi,
> >
> > On Fri, May 20, 2022 at 12:48 PM Matthias Kaehlcke <mka@chromium.org> wrote:
> > >
> > > Villager has a backlit keyboard, enable support for the backlight.
> > >
> > > Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> > > ---
> > >
> > >  arch/arm64/boot/dts/qcom/sc7280-herobrine-villager-r0.dts | 8 ++++++++
> > >  arch/arm64/boot/dts/qcom/sc7280-herobrine.dtsi            | 2 +-
> > >  2 files changed, 9 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm64/boot/dts/qcom/sc7280-herobrine-villager-r0.dts b/arch/arm64/boot/dts/qcom/sc7280-herobrine-villager-r0.dts
> > > index d3d6ffad4eff..b6a6a1454883 100644
> > > --- a/arch/arm64/boot/dts/qcom/sc7280-herobrine-villager-r0.dts
> > > +++ b/arch/arm64/boot/dts/qcom/sc7280-herobrine-villager-r0.dts
> > > @@ -58,6 +58,10 @@ &ap_sar_sensor1 {
> > >         status = "okay";
> > >  };
> > >
> > > +&keyboard_backlight {
> > > +       status = "okay";
> > > +};
> >
> > Instead of doing this, can you just get rid of the status = "disabled"
> > in herobrine.dtsi? I don't think there's any benefit to having two
> > levels of "disabled" in the herobrine device tree.
>
> Sure.
>
> I guess the 'disabled' status was put as a micro-optimization to avoid
> probing the 'pwm-leds' driver on boards that don't have any such LEDs. In
> practical terms it shouldn't really make a difference in terms of memory
> or CPU.

Just to be clear, I was suggesting leaving the "disabled" at the
pwm-leds level but removing the one at the "keyboard_backlight" level.
I don't expect us to have any pwm_leds on herobrine devices that
aren't for the keyboard backlight. If/when we do we can always add the
two-levels of disabled back in...

-Doug