linux-kernel - Re: [PATCH] arm64: dts: qcom: hamoa-iot-evk: enable pwm rgb leds

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Message-ID: <ada950ed-7b51-4e62-93ff-550c427a73fa@oss.qualcomm.com>
Date: Tue, 21 Oct 2025 14:29:22 +0800
From: Tingguo Cheng <tingguo.cheng@....qualcomm.com>
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>
Cc: Tingguo Cheng <tingguo.cheng@....qualcomm.com>, kernel@....qualcomm.com,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Kamal Wadhwa <kamal.wadhwa@....qualcomm.com>,
        Rakesh Kota <rakesh.kota@....qualcomm.com>,
        Fenglin Wu <fenglin.wu@....qualcomm.com>
Subject: Re: [PATCH] arm64: dts: qcom: hamoa-iot-evk: enable pwm rgb leds


On 10/17/2025 4:09 PM, Konrad Dybcio wrote:
> On 10/17/25 10:06 AM, Tingguo Cheng wrote:
>> Add red, green and blue LED channels for the RGB device connected to
>> PMC8380C PWM-LED pins.
>>
>> Signed-off-by: Tingguo Cheng<tingguo.cheng@....qualcomm.com>
>> ---
> Just to make sure, is this a "multicolor LED" consisting of 3 ones,
> and *not* three LEDs that are supposed to communicate different
> functions (i.e. network, power, disk i/o)?
Yes, it's a multicolor LED composed of three individual LEDs within a 
single package—not three separate LEDs for different functions like 
network, power, or disk I/O.
However, there's one exception worth mentioning:
The blue channel is connected to two sourcing signals—the EDL indicator 
and the PMIC PWM-RGB blue LED—via two resistors. These resistors allow 
selection between the two sources.
By default, the board is configured with the resistor soldered to 
connect the blue LED to the EDL indicator.
To support software control, I’ve added the blue channel in the DTS, 
enabling the capability to light the blue LED from the software side.
Some developers may choose to re-solder the resistor to connect the blue 
LED to the PMIC PWM-RGB output instead, depending on their hardware setup.
> Konrad