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

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 8/1/25 3:48 AM, Yijie Yang wrote:
> 
> 
> 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.

There is no DT representation of USB4 hardware at the moment, feel
free to pretend it doesn't exist for now.

If we wanted to be hyper-correct, the way USB(3) is plugged into the
bigger picture isn't quite pristine either, but that's a story for
another day - need some puzzle pieces to come together first

Konrad