linux-kernel - Re: [PATCH v3 4/4] arm64: dts: qcom: Add base HAMOA-IOT-EVK board

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Message-ID: <31b03c1b-513a-4eae-9233-568aab12e0c8@oss.qualcomm.com>
Date: Fri, 1 Aug 2025 09:48:10 +0800
From: Yijie Yang <yijie.yang@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: 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
Subject: Re: [PATCH v3 4/4] arm64: dts: qcom: Add base HAMOA-IOT-EVK board



On 2025-08-01 04:22, Dmitry Baryshkov wrote:
> On Thu, Jul 31, 2025 at 04:45:33PM +0800, Yijie Yang wrote:
>>
>>
>> On 2025-07-31 02:42, Dmitry Baryshkov wrote:
>>> On Wed, Jul 30, 2025 at 02:28:25PM +0800, Yijie Yang wrote:
>>>>
>>>>
>>>> On 2025-07-29 18:37, Dmitry Baryshkov wrote:
>>>>> On Tue, Jul 29, 2025 at 09:32:00AM +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 and overlays 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
>>>>>>
>>>
>>>
>>>>>> +	vreg_rtmr0_1p15: regulator-rtmr0-1p15 {
>>>>>
>>>>> Hmm, so there are regulators for the retimer, but they are not used.
>>>>> Could you please point out, why?
>>>>
>>>> According to the schematic, there is a regulator and a retimer (PS8830).
>>>> However, as mentioned above, the retimer is not connected to USB 0 and is
>>>> therefore not used in the EVK. As a result, the regulator is left unused in
>>>> this context.
>>>
>>> What is connected to the retimer then?
>>
>> All data lines are broken, except for some power lines.
> 
> Ok. please add a comment. If the retimer is connected to I2C bus, please
> define it too.

It’s not connected to I2C. I will add a comment here.

> 
>>
>>>
>>>>
>>>>>
>>>>>> +		compatible = "regulator-fixed";
>>>>>> +
>>>
>>> [...]
>>>
>>>>>> +
>>>>>> +	usb_1_ss0_sbu_default: usb-1-ss0-sbu-state {
>>>>>> +		mode-pins {
>>>>>> +			pins = "gpio166";
>>>>>> +			function = "gpio";
>>>>>> +			bias-disable;
>>>>>> +			drive-strength = <2>;
>>>>>> +			output-high;
>>>>>
>>>>> What does this pin do? It's not recommended to set GPIO values through
>>>>> pinctrl.
>>>>
>>>> It is used to switch data lines between USB Type-C orientation detection and
>>>> DisplayPort AUX channels.
>>>
>>> I don't think I follow it here. Which data lines? Type-C orientation
>>> detection uses CC1 / CC2, DP AUX use SBU lines.
>>
>> I made a mistake here — this pin switches between two data sources: one is
>> DP AUX, and the other is a GPIO pair configured with the function
>> usb0_sbrx/usb0_sbtx. Both data sources originate from the SoC and are routed
>> to the USB0_SBU1 and USB0_SBU2 lines of the USB Type-C connector.
> 
> So, it's some USB4 stuff. Ideally it should be described via the
> gpio-sbu-mux, but I don't think we can do that for now. I'd let Bjorn,
> Konrad or Abel comment on this.

Sure.

> 
>>
>>>
>>>> When this GPIO is high, USB0 operates in
>>>> orientation detection mode.
>>>
>>> What does this mean?
>>
>> This means the switch will select the GPIO pair configured as
>> usb0_sbrx/usb0_sbtx.
>>
>>>
>>>>
>>>>>
>>>>>> +		};
>>>>>> +
>>>>>> +		oe-n-pins {
>>>>>> +			pins = "gpio168";
>>>>>> +			function = "gpio";
>>>>>> +			bias-disable;
>>>>>> +			drive-strength = <2>;
>>>>>> +		};
>>>>>> +
>>>>>> +		sel-pins {
>>>>>> +			pins = "gpio167";
>>>>>> +			function = "gpio";
>>>>>> +			bias-disable;
>>>>>> +			drive-strength = <2>;
>>>>>> +		};
>>>>>> +	};
>>>>>> +
>>>>>> +	wcn_bt_en: wcn-bt-en-state {
>>>>>> +		pins = "gpio116";
>>>>>> +		function = "gpio";
>>>>>> +		drive-strength = <2>;
>>>>>> +		bias-disable;
>>>>>> +	};
>>>>>> +
>>>>>> +	wwan_sw_en: wwan-sw-en-state {
>>>>>> +		pins = "gpio221";
>>>>>> +		function = "gpio";
>>>>>> +		drive-strength = <4>;
>>>>>> +		bias-disable;
>>>>>> +	};
>>>>>> +
>>>>>> +	wcn_sw_en: wcn-sw-en-state {
>>>>>> +		pins = "gpio214";
>>>>>> +		function = "gpio";
>>>>>> +		drive-strength = <2>;
>>>>>> +		bias-disable;
>>>>>> +	};
>>>>>> +
>>>>>> +	wcn_usb_sw_n: wcn-usb-sw-n-state {
>>>>>
>>>>> What does this pin do? Using pinctrl to set GPIO values is not
>>>>> recommended AFAIR.
>>>>
>>>> This pin functions similarly to usb-1-ss0-sbu-state; it controls the data
>>>> switch between signals from the USB connector and WLAN data.
>>>
>>> Could you please explain it? Does it toggle USB2 signals(you've added it
>>> to the USB2 PHY) being routed either to the USB connector or to the WiFi
>>> card? Or do you mean something else?
>>
>> Yes, that's right. It routes signals between the USB connector and the M.2
>> Wi-Fi card.
> 
> Ack. Please add a comment.

Sure, I will.

> 
>>
>>>
>>>>>> +&usb_2_hsphy {
>>>>>> +	phys = <&eusb5_repeater>;
>>>>>> +
>>>>>> +	pinctrl-0 = <&wcn_usb_sw_n>;
>>>>>> +	pinctrl-names = "default";
>>>>>> +};
>>>>>> +
>>>>>> +&usb_mp_hsphy0 {
>>>>>> +	phys = <&eusb6_repeater>;
>>>>>> +};
>>>>>> +
>>>>>> +&usb_mp_hsphy1 {
>>>>>> +	phys = <&eusb3_repeater>;
>>>>>> +};
>>>>>>
>>>>>> -- 
>>>>>> 2.34.1
>>>>>>
>>>>>
>>>>
>>>> -- 
>>>> Best Regards,
>>>> Yijie
>>>>
>>>
>>
>> -- 
>> Best Regards,
>> Yijie
>>
> 

-- 
Best Regards,
Yijie