linux-kernel - Re: [PATCH v3 2/3] arm64: dts: qcom: trogdor: Add brightness-levels

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Message-ID: <CAD=FV=VeRs=EzBoQkVNVYnrEmUAwV0B-zKtYeS9s80TpEjPmgg@mail.gmail.com>
Date:   Thu, 22 Oct 2020 16:07:58 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Alexandru Stan <amstan@...omium.org>
Cc:     Heiko Stuebner <heiko@...ech.de>, Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        Enric Balletbo i Serra <enric.balletbo@...labora.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] arm64: dts: qcom: trogdor: Add brightness-levels

Hi,

On Wed, Oct 21, 2020 at 10:05 PM Alexandru Stan <amstan@...omium.org> wrote:
>
> We want userspace to represent the human perceived brightness.
> Since the led drivers and the leds themselves don't have a
> linear response to the value we give them in terms of perceived
> brightness, we'll bake the curve into the dts.
>
> The panel also doesn't have a good response under 5%, so we'll avoid
> sending it anything lower than that.
>
> Note: Ideally this patch should be coupled with the driver change from
> "backlight: pwm_bl: Fix interpolation", but it can work without it,
> without looking too ugly.
>
> Signed-off-by: Alexandru Stan <amstan@...omium.org>
> ---
>
>  arch/arm64/boot/dts/qcom/sc7180-trogdor.dtsi | 9 +++++++++
>  1 file changed, 9 insertions(+)

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