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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <305b9b6b-2003-48ab-97d0-c60226e1493b@oss.qualcomm.com>
Date: Tue, 28 Oct 2025 12:48:57 +0800
From: Tingguo Cheng <tingguo.cheng@....qualcomm.com>
To: Bjorn Andersson <andersson@...nel.org>
Cc: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>, 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 10/26/2025 11:15 AM, Bjorn Andersson wrote:
> On Tue, Oct 21, 2025 at 02:29:22PM +0800, Tingguo Cheng wrote:
>> 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.
> Sounds like we have a RG LED, and if the user chooses to modify their
> hardware, they have different hardware...which they can easily describe
> by updating their DeviceTree.
>
>
> It's a bit weird, but does it work to make this LED_COLOR_ID_MULTI with
> just the RED and GREEN channels described?

Yes, I tired before with enabling RED and GREEN only, it works. (What 
you said makes sense)

Let me send V2 for *only enabling RED and GREEN*

>
> Regards,
> Bjorn
>
>>> Konrad