linux-kernel - Re: [PATCH 2/5] arm64: dts: qcom: qcm6490-fairphone-fp5: Add VTOF_LDO

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Message-Id: <DDDOF3F8K5WQ.FTJ0F6E6DLPG@fairphone.com>
Date: Thu, 09 Oct 2025 11:16:18 +0200
From: "Luca Weiss" <luca.weiss@...rphone.com>
To: "Konrad Dybcio" <konrad.dybcio@....qualcomm.com>, "Luca Weiss"
 <luca.weiss@...rphone.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>, "Marijn Suijten" <marijn.suijten@...ainline.org>
Cc: <~postmarketos/upstreaming@...ts.sr.ht>, <phone-devel@...r.kernel.org>,
 <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/5] arm64: dts: qcom: qcm6490-fairphone-fp5: Add
 VTOF_LDO_2P8 regulator

Hi Konrad,

On Wed Oct 1, 2025 at 10:30 AM CEST, Konrad Dybcio wrote:
> On 9/30/25 3:57 PM, Luca Weiss wrote:
>> Describe yet another regulator-fixed on this board, powering the ToF
>> sensor.
>> 
>> Signed-off-by: Luca Weiss <luca.weiss@...rphone.com>
>> ---
>>  arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts | 13 +++++++++++++
>>  1 file changed, 13 insertions(+)
>> 
>> diff --git a/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts b/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts
>> index 36d5750584831d66b4c2faf6042e4cbb3274eca7..0a64e5721e092d1f3e4bb7329335704eee567761 100644
>> --- a/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts
>> +++ b/arch/arm64/boot/dts/qcom/qcm6490-fairphone-fp5.dts
>> @@ -195,6 +195,19 @@ vreg_usb_redrive_1v8: regulator-usb-redrive-1v8 {
>>  		pinctrl-names = "default";
>>  	};
>>  
>> +	vreg_vtof_ldo_2p8: regulator-vtof-ldo-2p8 {
>> +		compatible = "regulator-fixed";
>> +		regulator-name = "VTOF_LDO_2P8";
>> +		regulator-min-microvolt = <2800000>;
>> +		regulator-max-microvolt = <2800000>;
>> +		regulator-enable-ramp-delay = <233>;
>> +
>> +		gpio = <&tlmm 141 GPIO_ACTIVE_HIGH>;
>
> You may want to define the pincfg/mux config for this gpio too

While I wouldn't say it's not good to have it, there's plenty of GPIOs
that have no pinctrl for it. Downstream doesn't set anything for gpio141
either.

I honestly wouldn't even know what the 'default' for a GPIO is in the
first place, or could I query the runtime state from the kernel? Is
/sys/kernel/debug/pinctrl/f100000.pinctrl/pinconf-groups trustworthy to
solidify this in the dts?

141 (gpio141): input bias disabled, output drive strength (2 mA), output enabled, pin output (0 level)

Regards
Luca

>
> Konrad