Message-ID: <469d89c9-8f6c-4abe-9d9f-b6a47f8cefd8@oss.qualcomm.com>
Date: Mon, 5 Jan 2026 13:36:08 +0800
From: Tingwei Zhang <tingwei.zhang@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Yijie Yang <yijie.yang@....qualcomm.com>, andersson@...nel.org,
        konradybcio@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
        conor+dt@...nel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 3/4] arm64: dts: qcom: Commonize IQ-X-IOT DTSI



On 12/30/2025 3:21 PM, Krzysztof Kozlowski wrote:
> On 29/12/2025 21:08, Dmitry Baryshkov wrote:
>> On Mon, Dec 29, 2025 at 09:47:05AM +0100, Krzysztof Kozlowski wrote:
>>> On 29/12/2025 08:38, Yijie Yang wrote:
>>>>
>>>> On 12/29/2025 3:21 PM, Krzysztof Kozlowski wrote:
>>>>> On 29/12/2025 02:23, Tingwei Zhang wrote:
>>>>>>
>>>>>> On 12/24/2025 8:12 AM, Tingwei Zhang wrote:
>>>>>>> On 12/23/2025 9:41 PM, Krzysztof Kozlowski wrote:
>>>>>>>> On 23/12/2025 04:38, Tingwei Zhang wrote:
>>>>>>>>> On 12/22/2025 5:11 PM, Krzysztof Kozlowski wrote:
>>>>>>>>>> On Mon, Dec 22, 2025 at 02:03:28PM +0800, YijieYang wrote:
>>>>>>>>>>> From: Yijie Yang <yijie.yang@....qualcomm.com>
>>>>>>>>>>>
>>>>>>>>>>> HAMOA-IOT-EVK and PURWA-IOT-EVK share a similar board design. Extract
>>>>>>>>>>> the common components into separate files for better maintainability.
>>>>>>>>>> SoMs do not share actual hardware. DTSI does not represent what looks
>>>>>>>>>> similar to you, but actually common parts.
>>>>>>>>> Purwa SOM board and Hamoa SOM board share same design. They share same PCB.
>>>>>>>>> The difference is only on chip. Purwa SOM board has Purwa and Hamoa SOM board
>>>>>>>>> has Hamoa on it.
>>>>>>>> I do not speak about boards. Read carefully feedback and respond to the
>>>>>>>> actual feedback, not some other arguments.
>>>>>>>>
>>>>>>>> NAK
>>>>>>> In this change, the SoM hardware except SoC is described by iq-x-iot-som.dtsi since it's common between Hamoa and Purwa. Hamoa and Purwa SoC hardware is described in hamoa.dtsi and purwa.dtsi. Hamoa-iot-som.dtsi includes iq-x-iot-som.dtsi and hamoa.dtsi. This change could reduce the duplicate code and review effort on a totally new purwa-iot-som.dtsi. If we found any bug, it can be fixed in one common file instead of two separate files. Same idea is used in x1-crd.dtsi. X1e80100-crd.dts include x1-crd.dtsi and hamoa.dtsi.
>>>>>> Krzysztof,
>>>>>> Please let me know your opinion on this. This could be a common case for
>>>>>> Hamoa/Purwa boards share same PCB. Share same dtsi file like x1-crd.dtsi
>>>>> It's not the same PCB.  You did not really respond to my first message,
>>>>> so I responded to you - I do not speak about boards. Then again you did
>>>>> not respond to it and brought some irrelevant arguments.
>>>>>
>>>>>> would reduce maintenance effort.
>>>>> Does not matter, I do not question this. Why are you responding to some
>>>>> questions which were never asked?
>>>>>
>>>>> DTSI represents actual shared physical aspect and you cannot share SoM
>>>>> physically. It's not the same PCB, because you do not have a socket on
>>>>> the SoM.
>>>> x1e80100-crd and x1p42100-crd are different boards, yet they share the 
>>>> same x1-crd.dtsi. Why can’t we apply the same approach here?
>>>
>>> You should ask the authors there, not me. I presume that the baseboard
>>> is the same or very similar. Or pieces of the baseboard are re-used
>>> which could be visible in the schematics (same MCN numbers etc).
>> For me this sounds like a new rule, which didn't exist beforehand. We
>> have enough foo-common.dtsi fragments, covering similar phones, but we
>> never required the knowledge of those phones having the same PCB.
> I am speaking about it since 2020? 2021? So how new? Other people in
> other SoCs were sometimes speaking about it in 2016 or something
There’s no doubt that using a common DTSI makes sense when the boards
share the same baseboard.
I think the real question is whether the baseboards are defined so
similarly that they can be treated as the same.
For example, would swapping to a different SoC—similar to the
Hamoa/Purwa CRD scenario—still be acceptable?
Would exchanging components such as the display panel, a single camera
lens (not the sensor, as far as I can tell), or removing the 3D iToF
module[1] still qualify as the “same” board?
In other words, can we consider two boards identical if the underlying
circuit board is the same but a few parts are swapped out?

[1]https://lore.kernel.org/all/20221114095654.34561-3-konrad.dybcio@linaro.org/
> Best regards,
> Krzysztof

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