linux-kernel - Re: [PATCH v11 4/4] arm64: dts: qcom: Add base HAMOA-IOT-EVK board

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Message-ID: <ee2d0d92-bff9-4593-a912-7e4b1d66913b@oss.qualcomm.com>
Date: Tue, 16 Sep 2025 12:36:02 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Yingying Tang <quic_yintang@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Stephan Gerhold <stephan.gerhold@...aro.org>,
        Yijie Yang <yijie.yang@....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>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Yingying Tang <yingying.tang@....qualcomm.com>,
        Shuai Zhang <shuaz@....qualcomm.com>
Subject: Re: [PATCH v11 4/4] arm64: dts: qcom: Add base HAMOA-IOT-EVK board

On 9/16/25 12:29 PM, Yingying Tang wrote:
> 
> 
> On 9/16/2025 6:14 PM, Dmitry Baryshkov wrote:
>> On Tue, Sep 16, 2025 at 09:42:26AM +0800, Yingying Tang wrote:
>>>
>>>
>>> On 9/12/2025 5:00 PM, Stephan Gerhold wrote:
>>>> On Wed, Sep 10, 2025 at 05:02:12PM +0800, Yijie Yang wrote:
>>>>> The HAMOA-IOT-EVK is an evaluation platform for IoT products, composed of
>>>>> the Hamoa IoT SoM and a carrier board. Together, they form a complete
>>>>> embedded system capable of booting to UART.
>>>>>
>>>>> Make the following peripherals on the carrier board enabled:
>>>>> - UART
>>>>> - On-board regulators
>>>>> - USB Type-C mux
>>>>> - Pinctrl
>>>>> - Embedded USB (EUSB) repeaters
>>>>> - NVMe
>>>>> - pmic-glink
>>>>> - USB DisplayPorts
>>>>> - Bluetooth
>>>>> - WLAN
>>>>> - Audio
>>>>>
>>>>> Written in collaboration with Quill Qi (Audio) <le.qi@....qualcomm.com>,
>>>>> Jie Zhang (Graphics) <quic_jiezh@...cinc.com>, Shuai Zhang (Bluetooth)
>>>>> <quic_shuaz@...cinc.com>, Yingying Tang (WLAN) <quic_yintang@...cinc.com>,
>>>>> and Yongxing Mou (USB DisplayPorts) <quic_yongmou@...cinc.com>.
>>>>
>>>> This looks like you should have Co-developed-by: tags together with
>>>> their Signed-off-by: tags.
>>>>
>>>>>
>>>>> Signed-off-by: Yijie Yang <yijie.yang@....qualcomm.com>
>>>>> ---
>>>>>  arch/arm64/boot/dts/qcom/Makefile          |    1 +
>>>>>  arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts | 1221 ++++++++++++++++++++++++++++
>>>>>  2 files changed, 1222 insertions(+)
>>>>>
>>>>> +
>>>>> +	vreg_wcn_3p3: regulator-wcn-3p3 {
>>>>> +		compatible = "regulator-fixed";
>>>>> +
>>>>> +		regulator-name = "VREG_WCN_3P3";
>>>>> +		regulator-min-microvolt = <3300000>;
>>>>> +		regulator-max-microvolt = <3300000>;
>>>>> +
>>>>> +		gpio = <&tlmm 214 GPIO_ACTIVE_HIGH>;
>>>>> +		enable-active-high;
>>>>> +
>>>>> +		pinctrl-0 = <&wcn_sw_en>;
>>>>> +		pinctrl-names = "default";
>>>>> +
>>>>
>>>> regulator-boot-on?
>>>
>>> It shoulde be regulator-always-on
>>
>> Why it's not boot-on and always-on?
>>
> As I described before, connectivity power is voted by UEFI in boot phase.So PCIe link between connetivity card and RC4 is established once RC4 is on.
> If we set this node as "regulator-boot-on", connectivity power will be down first then up. That cause PCIe link down and the link can't be trained again unless you reboot board.
> So we can't set it to "regulator-boot-on"

Surely gpio-regulator.c implements .get_voltage which reads the pin
state though? Did you test this, or are you theorycrafting?

Konrad