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Date:   Thu, 23 Mar 2023 20:54:24 +0100
From:   Pavel Machek <pavel@ucw.cz>
To:     Fenglin Wu <quic_fenglinw@quicinc.com>
Cc:     Luca Weiss <luca.weiss@fairphone.com>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linux-arm-msm@vger.kernel.org, linux-leds@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] arm64: dts: qcom: sm7225-fairphone-fp4: configure
 flash LED
Message-ID: <ZByucIecBARC/2X2@duo.ucw.cz>
References: <20221209-fp4-pm6150l-flash-v1-0-531521eb2a72@fairphone.com>
 <20221209-fp4-pm6150l-flash-v1-3-531521eb2a72@fairphone.com>
 <Y5S+6j1yJ62RJU/v@duo.ucw.cz>
 <COZW5FAXA36Z.175ARPIESQSLL@otso>
 <ab314039-2c69-8afa-cfb2-e5876ac6afe2@quicinc.com>
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Hi!


> > > I'm pretty sure the flash is not yellow.
> >=20
> > The marketing term is Dual LED flash or Dual-tone flash, one LED is a
> > blue-ish white and one is a yellow-ish white, but from what I can tell,
> > in the original code it's always referred to as white and yellow so I
> > also followed that here.
> >=20
> > Also the LEDs are right next to each other so in practise for torch just
> > both go on, and for camera flash I cannot really tell you but I guess
> > it's doing something there with the camera tuning.
> >=20
> > See also this picture:
> > https://shop.fairphone.com/media/catalog/product/cache/b752d78484639b19=
641a8560800d919d/p/_/p_5b_main_camera_back.jpg
> >=20
> Hi Pavel,
>=20
> Luca is right. It is normally called dual CCT (Correlated Color Temperatu=
re)
> flash LED. It has 2 LEDs, one is with higher CCT (~6000K) so it looks lik=
e a
> white LED, another is with lower CCT (~2000K) and it looks like a yellow
> LED. I am not an expert of this but my understanding is the camera tuning
> process normally adjusts the brightness of the two LEDs and enables them =
to
> get different CCT for different snapshots.

I believe this is normally called "warm white" and "cool white", no?
Yellow would be monochromatic light at cca 575nm, see
https://en.wikipedia.org/wiki/Shades_of_yellow .

If we need to add some defines for that, lets do that.

BR,
									Pavel
--=20
People of Russia, stop Putin before his war on Ukraine escalates.

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