linux-kernel - Re: [PATCH v7 2/5] dt-bindings: leds: Add LED_COLOR_ID

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Message-ID: <31804c28-fa2b-9b1d-2d10-63de70d2fbd8@gmail.com>
Date:   Tue, 24 Nov 2020 22:38:25 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Gene Chen <gene.chen.richtek@...il.com>
Cc:     Pavel Machek <pavel@....cz>, Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Dan Murphy <dmurphy@...com>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Gene Chen <gene_chen@...htek.com>, Wilma.Wu@...iatek.com,
        shufan_lee@...htek.com, cy_huang@...htek.com,
        benjamin.chao@...iatek.com
Subject: Re: [PATCH v7 2/5] dt-bindings: leds: Add LED_COLOR_ID_MOONLIGHT
 definitions

On 11/24/20 8:33 AM, Gene Chen wrote:
> Jacek Anaszewski <jacek.anaszewski@...il.com> 於 2020年11月24日 週二 上午4:52寫道：
>>
>> On 11/23/20 4:00 AM, Gene Chen wrote:
>>> Jacek Anaszewski <jacek.anaszewski@...il.com> 於 2020年11月20日 週五 上午6:26寫道：
>>>>
>>>> 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@...htek.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 evening...
>>>>>
>>>>> 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 class
>>>> 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’t want something that’s 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?

Regarding the function - yes, the reference backs that up.
Regarding the color - if you feel that it properly describes the
LED color then go for it.

-- 
Best regards,
Jacek Anaszewski