linux-kernel - Re: [PATCH v3 1/3] ARM: dts: rockchip: veyron: Remove 0 point from brightness-levels

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Message-ID: <CAD=FV=Vf2wfPK7CCwHi65ubPnCPWJw4Qh2nKtfC=yx7h8pvuyg@mail.gmail.com>
Date:   Thu, 22 Oct 2020 16:05:48 -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 <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH v3 1/3] ARM: dts: rockchip: veyron: Remove 0 point from brightness-levels

Hi,

On Wed, Oct 21, 2020 at 10:05 PM Alexandru Stan <amstan@...omium.org> wrote:
>
> The extra 0 only adds one point in the userspace visible range,
> so this change is almost a noop with the current driver behavior.
>
> We don't need the 0% point, userspace seems to handle this just fine
> because it uses the bl_power property to turn off the display.
>
> Furthermore after adding "backlight: pwm_bl: Fix interpolation" patch,
> the backlight interpolation will work a little differently. So we need
> to preemptively remove the 0-3 segment since otherwise we would have a
> 252 long interpolation that would slowly go between 0 and 3, looking
> really bad in userspace. So it's almost a noop/cleanup now, but it will
> be required in the future.
>
> Signed-off-by: Alexandru Stan <amstan@...omium.org>
> ---
>
>  arch/arm/boot/dts/rk3288-veyron-jaq.dts    | 2 +-
>  arch/arm/boot/dts/rk3288-veyron-minnie.dts | 2 +-
>  arch/arm/boot/dts/rk3288-veyron-tiger.dts  | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)

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