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From:   Gene Chen <gene.chen.richtek@gmail.com>
Date:   Tue, 24 Nov 2020 15:33:42 +0800
Message-ID: <CAE+NS34vDejgf8Ydfer_rY25qaG-DQQ5H-9-Er+Shz0=UF-EzA@mail.gmail.com>
Subject: Re: [PATCH v7 2/5] dt-bindings: leds: Add LED_COLOR_ID_MOONLIGHT definitions
To:     Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc:     Pavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Dan Murphy <dmurphy@ti.com>,
        Linux LED Subsystem <linux-leds@vger.kernel.org>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Gene Chen <gene_chen@richtek.com>, Wilma.Wu@mediatek.com,
        shufan_lee@richtek.com, cy_huang@richtek.com,
        benjamin.chao@mediatek.com
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Jacek Anaszewski <jacek.anaszewski@gmail.com> =E6=96=BC 2020=E5=B9=B411=E6=
=9C=8824=E6=97=A5 =E9=80=B1=E4=BA=8C =E4=B8=8A=E5=8D=884:52=E5=AF=AB=E9=81=
=93=EF=BC=9A
>
> On 11/23/20 4:00 AM, Gene Chen wrote:
> > Jacek Anaszewski <jacek.anaszewski@gmail.com> =E6=96=BC 2020=E5=B9=B411=
=E6=9C=8820=E6=97=A5 =E9=80=B1=E4=BA=94 =E4=B8=8A=E5=8D=886:26=E5=AF=AB=E9=
=81=93=EF=BC=9A
> >>
> >> On 11/19/20 10:57 PM, Pavel Machek wrote:
> >>> On Thu 2020-11-19 22:03:14, Jacek Anaszewski wrote:
> >>>> Hi Pavel, Gene,
> >>>>
> >>>> On 11/18/20 10:37 PM, Pavel Machek wrote:
> >>>>> Hi!
> >>>>>
> >>>>>> From: Gene Chen <gene_chen@richtek.com>
> >>>>>>
> >>>>>> Add LED_COLOR_ID_MOONLIGHT definitions
> >>>>>
> >>>>> Why is moonlight a color? Camera flashes are usually white, no?
> >>>>>
> >>>>> At least it needs a comment...
> >>>>
> >>>> That's my fault, In fact I should have asked about adding
> >>>> LED_FUNCTION_MOONLIGHT, it was evidently too late for me that evenin=
g...
> >>>
> >>> Aha, that makes more sense.
> >>>
> >>> But please let's call it "torch" if we do that, as that is already
> >>> used in kernel sources... and probably in the interface, too:
> >>
> >> I'd say that torch is something different that moonlight,
> >> but we would need more input from Gene to learn more about
> >> the nature of light emitted by ML LED on his device.
> >>
> >> Please note that torch is usually meant as the other mode of
> >> flash LED (sometimes it is called "movie mode"), which is already
> >> handled by brightness file of LED class flash device (i.e. its LED cla=
ss
> >> subset), and which also maps to v4l2-flash TORCH mode.
> >>
> >
> > It's used to front camera fill light.
> > More brightness than screen backlight, and more soft light than flash.
> > I think LED_ID_COLOR_WHITE is okay.
>
> So why in v6 you assigned LED_COLOR_ID_AMBER to it?
>
> Regardless of that, now we're talking about LED function - you chose
> LED_FUNCTION_INDICATOR for it, but inferring from your above description
> - it certainly doesn't fit here.
>
> Also register names, containing part "ML" indicate that this LED's
> intended function is moonlinght, which your description somehow
> corroborates.
>
> Moonlight LEDs become ubiquitous nowadays so sooner or later we will
> need to add this function anyway [0].
>
> [0]
> https://landscapelightingoakville.com/what-is-moon-lighting-and-why-does-=
it-remain-so-popular/
>

We use term "Moonlight" as reference says
"When you are trying to imitate moonlight you need to use low voltage,
softer lighting. You don=E2=80=99t want something that=E2=80=99s too bright=
"
which is focus on brightness instead of color.

So we surpose Moonlight can be white or amber.

Should I add LED_FUNCTION_MOONLIGHT and set LED_COLOR_ID_WHITE?

> --
> Best regards,
> Jacek Anaszewski