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From:   Doug Anderson <dianders@chromium.org>
Date:   Tue, 13 Oct 2020 09:28:38 -0700
Message-ID: <CAD=FV=W4fv_AdS7G2FFe2Kan3YYJ4D0MVJD90aJMrgCja5N4vg@mail.gmail.com>
Subject: Re: [PATCH v2 3/3] arm64: dts: qcom: trogdor: Add brightness-levels
To:     Alexandru Stan <amstan@chromium.org>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        =?UTF-8?Q?Uwe_Kleine=2DK=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>, Lee Jones <lee.jones@linaro.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Jingoo Han <jingoohan1@gmail.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Heiko Stuebner <heiko@sntech.de>,
        Rob Herring <robh+dt@kernel.org>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Enric Balletbo i Serra <enric.balletbo@collabora.com>,
        Matthias Kaehlcke <mka@chromium.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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Hi,

On Tue, Oct 13, 2020 at 1:01 AM Alexandru Stan <amstan@chromium.org> wrote:
>
> Now that we have better interpolation for the backlight
> ("backlight: pwm_bl: Fix interpolation"), we can now add the curve to
> the trogdor boards, being careful to crop the low end.

Just to make it clear, the patch this depends on hasn't landed yet.
Presumably it will land in the v5.10 timeframe?  That means that
without extra coordination this patch can target v5.11.


> Signed-off-by: Alexandru Stan <amstan@chromium.org>
> ---
>
>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> index bf875589d364..ccdabc6c4994 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi
> @@ -179,6 +179,15 @@ pp3300_fp_tp: pp3300-fp-tp-regulator {
>         backlight: backlight {
>                 compatible = "pwm-backlight";
>
> +               /* The panels don't seem to like anything below ~ 5% */
> +               brightness-levels = <
> +                       196 256 324 400 484 576 676 784 900 1024 1156 1296
> +                       1444 1600 1764 1936 2116 2304 2500 2704 2916 3136
> +                       3364 3600 3844 4096
> +               >;
> +               num-interpolated-steps = <64>;
> +               default-brightness-level = <951>;

I haven't done lots of digging here, but this matches what Alexandru
and Matthias agreed upon for the downstream tree and seems sane.
Thus:

Reviewed-by: Douglas Anderson <dianders@chromium.org>