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

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Message-ID: <lfdgxbezefncmyw6euac6navuaiq25jjrrd4j3sabwjbi5adth@sx76za7f2e5a>
Date: Tue, 2 Sep 2025 12:50:54 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Yingying Tang <quic_yintang@...cinc.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 Tue, Sep 02, 2025 at 02:56:37PM +0800, 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.
> >>>>
> >>>> This change enables the following peripherals on the carrier board:
> >>>> - UART
> >>>> - On-board regulators
> >>>> - USB Type-C mux
> >>>> - Pinctrl
> >>>> - Embedded USB (EUSB) repeaters
> >>>> - NVMe
> >>>> - pmic-glink
> >>>> - USB DisplayPorts
> >>>> - Bluetooth
> >>>> - Graphic
> >>>> - 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>, and Yongxing Mou (USB DisplayPorts)
> >>>> <quic_yongmou@...cinc.com>.
> >>>>
> >>>> 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 | 1247 ++++++++++++++++++++++++++++
> >>>>  2 files changed, 1248 insertions(+)
> >>>>
> >>>> +
> >>>> +	wcd938x: audio-codec {
> >>>> +		compatible = "qcom,wcd9385-codec";
> >>>> +
> >>>> +		pinctrl-0 = <&wcd_default>;
> >>>> +		pinctrl-names = "default";
> >>>> +
> >>>> +		reset-gpios = <&tlmm 191 GPIO_ACTIVE_LOW>;
> >>>> +
> >>>> +		qcom,micbias1-microvolt = <1800000>;
> >>>> +		qcom,micbias2-microvolt = <1800000>;
> >>>> +		qcom,micbias3-microvolt = <1800000>;
> >>>> +		qcom,micbias4-microvolt = <1800000>;
> >>>> +		qcom,mbhc-buttons-vthreshold-microvolt = <75000 150000 237000 500000
> >>>> +		500000 500000 500000 500000>;
> >>>
> >>> Other platforms use a single line here. If you don't want to do it,
> >>> align data to start from the same column rather than restarting from the
> >>> column 1.
> >>>
> >>>> +		qcom,mbhc-headset-vthreshold-microvolt = <1700000>;
> >>>> +		qcom,mbhc-headphone-vthreshold-microvolt = <50000>;
> >>>> +		qcom,rx-device = <&wcd_rx>;
> >>>> +		qcom,tx-device = <&wcd_tx>;
> >>>> +
> >>>> +		vdd-buck-supply = <&vreg_l15b_1p8>;
> >>>> +		vdd-rxtx-supply = <&vreg_l15b_1p8>;
> >>>> +		vdd-io-supply = <&vreg_l15b_1p8>;
> >>>> +		vdd-mic-bias-supply = <&vreg_bob1>;
> >>>> +
> >>>> +		#sound-dai-cells = <1>;
> >>>> +	};
> >>>> +
> >>>> +	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.

Here you are describing driver behaviour. It's a software issue and
can be handled in the driver.

I'm asking you to describe the hardware. From the hardware perspective
there is a GPIO pin. Please describe it in the DT.

> So I didn't add wlan-en-gpio in this hamoa's device tree.
> 
> 
> 
> > 
> >>
> >> So we need not Wifi chip's power and control GPIO in kernel side, thanks 
> > 
> > What if someone requests this GPIO from userspace and pulls it down?
> > 
> >>>> +
> >>>> +		pinctrl-0 = <&wcn_bt_en>;
> >>>> +		pinctrl-names = "default";
> >>>> +
> >>>
> >>
> > 
> 

-- 
With best wishes
Dmitry