linux-kernel - Re: [PATCH v5 3/3] arm64: dts: qcom: monaco-evk-camera: Add DT overlay

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Message-ID: <22350774-20da-42ff-a6c2-02fab121f4b5@quicinc.com>
Date: Sat, 15 Nov 2025 11:23:30 +0530
From: Nihal Kumar Gupta <quic_nihalkum@...cinc.com>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
        Vikram Sharma
	<quic_vikramsa@...cinc.com>,
        <bryan.odonoghue@...aro.org>, <mchehab@...nel.org>, <robh@...nel.org>,
        <krzk+dt@...nel.org>, <conor+dt@...nel.org>, <andersson@...nel.org>,
        <konradybcio@...nel.org>, <hverkuil-cisco@...all.nl>,
        <cros-qcom-dts-watchers@...omium.org>, <catalin.marinas@....com>,
        <will@...nel.org>
CC: <linux-arm-kernel@...ts.infradead.org>, <quic_svankada@...cinc.com>,
        <linux-media@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Ravi Shankar
	<quic_rshankar@...cinc.com>,
        Vishal Verma <quic_vishverm@...cinc.com>,
        Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>
Subject: Re: [PATCH v5 3/3] arm64: dts: qcom: monaco-evk-camera: Add DT
 overlay



On 15-11-2025 03:49, Konrad Dybcio wrote:
>> +&{/} {
>> +	vreg_cam1_2p8: vreg-cam1-2p8 {
> Where does this regulator lie physically? Is its presence dependent
> on the connection of the sensor, is it part of the EVK carrier board,
> or perhaps something else?
vreg_cam1_2p8 is a fixed 2.8 V regulator located on the EVK carrier board. 
It supplies the camera sensor’s AVDD rail and is enabled via GPIO 74, which is controlled by the TLMM block. 

> 
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "vreg_cam1_2p8";
>> +		startup-delay-us = <10000>;
>> +		enable-active-high;
>> +		gpio = <&tlmm 74 GPIO_ACTIVE_HIGH>;
>> +		pinctrl-names = "default";
>> +		pinctrl-0 = <&cam1_avdd_2v8_en_default>;
> property-n
> property-names
> 
> please
> 
ACK

> [...]
> 
>> +&tlmm {
>> +	/*
>> +	 * gpio67, gpio68, gpio69 provide MCLK0, MCLK1, MCLK2 for
>> +	 * CAM0, CAM1 and CAM2 respectively via the "cam_mclk" function.
>> +	 * So, here it's MCLK1 pin for instance.
>> +	 */
> I don't really see the value in these comments..
> 
> Vladimir requested you to move the 'description' (meaning the node
> describing the hardware, not a comment explaining the function of the
> DT hunk in natural language) to monaco.dtsi too
I’ve added descriptions to indicate which pins enable which camera MCLK/Regulators. If these aren’t considered useful, I can remove them.

Should I need to add hardware descriptions for all GPIOs (gpio67–69 for MCLK and gpio73–75 for regulator enable), even if they are unused?

I have referenced qcs6490-rb3gen2-vision-mezzanine.dtso for the MCLK pin hardware description (cam1_default).
All TLMM GPIOs mentioned above are muxed pins. As Bryan suggested in v4, these should go into the mezzanine-specific dtso. Do I need to extend this in monaco.dtsi as well?

-- 
Regards,
Nihal Kumar Gupta