linux-kernel - Re: [PATCH 1/4] ARM: dts: qcom: msm8974pro-htc-m8: add status LEDs

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Message-ID: <77efe2a2-ee81-4096-9145-a76e35954e84@me.ssier.org>
Date: Wed, 22 Oct 2025 03:00:01 -0400
From: Alexandre Messier <alex@...ssier.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Pavel Machek <pavel@...nel.org>
Cc: Luca Weiss <luca@...aweiss.eu>, linux-arm-kernel@...ts.infradead.org,
 linux-arm-msm@...r.kernel.org, ~postmarketos/upstreaming@...ts.sr.ht,
 phone-devel@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] ARM: dts: qcom: msm8974pro-htc-m8: add status LEDs

On 2025-10-20 08:02, Konrad Dybcio wrote:
> On 10/12/25 8:03 AM, Alexandre Messier wrote:
>> On 2025-10-07 06:03, Konrad Dybcio wrote:
>>> On 10/7/25 7:55 AM, Alexandre Messier via B4 Relay wrote:
>>>> From: Alexandre Messier <alex@...ssier.org>
>>>>
>>>> Add support for the notification LEDs on the HTC One M8.
>>>>
>>>> Two LEDs are available, one amber and one green.
>>>
>>> Do they form a single notification led, or are they supposed
>>> to act separately?
>>
>> Good point, I had to check the phone user manual to confirm. Indeed, it is
>> referred to as a one logical notification LED. It also mentions the color can
>> be either green or orange, it does not mention using the combined color of
>> the two LEDs.
>>
>> So I would say they are supposed to act separately.
>>
>> Hope this answers your question, and let me know if more details are needed.
>>
>> BTW: I will be sending a V2 to update the color name, since the user
>> manual says the color is orange, not amber.
> 
> Let's describe it as a single LED then:
> 
> multi-led {
>         color = <LED_COLOR_ID_MULTI>; // notice it's not RGB
>         function = LED_FUNCTION_STATUS;
> 
>         #address-cells = <1>;
>         #size-cells = <0>;
> 
>         led@6 {
>                 reg = <6>;
>                 color = <LED_COLOR_ID_GREEN>;
>         };
> 
>         led@7 {
>                 reg = <7>;
>                 color = <LED_COLOR_ID_ORANGE>;
>         };
> };

Using multi-led is fine for me.

But currently, the "qcom-lpg" driver doesn't support LED_COLOR_ID_MULTI, only
LED_COLOR_ID_RGB. Adding support for LED_COLOR_ID_MULTI is trivial, I tested it
and it works.

Or I can also use the "leds-group-multicolor" driver, using the two individual
LEDs. I also tested this method and it works.

> 
> + Pavel the LED maintainer, please take a look if you think it makes sense

If Pavel agrees using multi-led makes sense, I think the first option is the
best. I will separate the LED patch into a new series, along with the change to
the qcom-lpg driver to support LED_COLOR_ID_MULTI.

Thanks
Alex

> 
> Konrad