linux-kernel - Re: [PATCH v8 3/3] arm64: dts: qcom: Add base HAMOA-IOT-EVK board

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Message-ID: <d13d416d-507c-4f74-91f5-38447ac39599@oss.qualcomm.com>
Date: Tue, 2 Sep 2025 12:09:26 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Yingying Tang <quic_yintang@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: 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 <yintang@....qualcomm.com>,
        miaoqing.pan@....qualcomm.com,
        "stone Zhang (Stone)" <stonez@....qualcomm.com>,
        zhichen@....qualcomm.com
Subject: Re: [PATCH v8 3/3] arm64: dts: qcom: Add base HAMOA-IOT-EVK board

On 9/2/25 8:56 AM, Yingying Tang wrote:
> 
> 
> On 9/2/2025 10:37 AM, Dmitry Baryshkov wrote:
>> On Mon, Sep 01, 2025 at 11:02:24AM +0800, Yingying Tang wrote:
>>>
>>>
>>> On 8/28/2025 7:18 PM, Dmitry Baryshkov wrote:
>>>> On Thu, Aug 28, 2025 at 12:48:47PM +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.

[...]

>>>>> +	wcn7850-pmu {
>>>>> +		compatible = "qcom,wcn7850-pmu";
>>>>> +
>>>>> +		vdd-supply = <&vreg_wcn_0p95>;
>>>>> +		vddio-supply = <&vreg_l15b_1p8>;
>>>>> +		vddaon-supply = <&vreg_wcn_0p95>;
>>>>> +		vdddig-supply = <&vreg_wcn_0p95>;
>>>>> +		vddrfa1p2-supply = <&vreg_wcn_1p9>;
>>>>> +		vddrfa1p8-supply = <&vreg_wcn_1p9>;
>>>>> +
>>>>> +		bt-enable-gpios = <&tlmm 116 GPIO_ACTIVE_HIGH>;
>>>>
>>>> Okay, so how is WiFi controlled? Is there a GPIO? The DT should be
>>>> describing the hardware, not the UEFI behaviour.
>>>>
>>> Hi Dmitry, as I described in previous mail, On hamoa platfrom whole wifi module's power supply and enable gpio are voted in UEFI.
>>> Hamoa is PC platform, so BIOS/UEFI behavior is compatible with Windows/ACPI architecture. UEFI is responsible for enabling power supply 
>>> for all devices which may be used in boot phase (such as WLAN may be used to boot from network).
>>
>> This is not completely relevant. You are describing driver / Linux /
>> bootloader behaviour. I asked if there is a GPIO in the hardware. If
>> there is one, please add it here.
> 
> Hi Dimitry,
> 
> During the UEFI boot phase, the WLAN enable GPIO has already been asserted, and the WLAN chip is functioning normally. 
> If we include this GPIO in the kernel device tree, when the kernel configures this GPIO, its voltage level may experience a brief glitch, which could cause the WLAN chip to reset and result in a PCIe link down.

The WCN pwrseq code handles this already, please simply describe the
hardware like the platform firmware description which you're creating
is supposed to

Konrad