Message-ID: <bab3794d-d7f8-492a-82a2-6a8a6f80a708@oss.qualcomm.com>
Date: Tue, 6 Jan 2026 09:24:38 +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 1/5/2026 11:09 PM, Krzysztof Kozlowski wrote:
> On 05/01/2026 06:36, Tingwei Zhang wrote:
>>
>> 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.
> HERE - socket.
>
>>>>>> 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?
> I received IDs of the schematics for these boards, but they are called
> "IPC BGA module" and what I saw usually is that BGA modules are not
> mountable but solderable. This does not matter that much but should have
> been said, because it might mean this is not even a SoM. There are many
> SoMs which are BGA, not pluggable or pin-based, but I have just doubts
> that authors share everything...
Thanks for taking the time and review the schematics. That's soldered BGA 
modules. It's SoM since that's a module with minimal system including
SoC, PMIC, DDR. This module is available for customer to order so customer
can focus on carrier board. The hardware and software of SoM can be
reused.
> Anyway the BGA modules for Hamoa and Purwa have almost the same
> schematics, indeed, except differences in PCI, APC supply and lack of
> one PMIC.
Yes. These two modules are very similar.
> If this was the same SoM, just with different SoC soldered, it would
> have the same PMICs. Different PMICs means different SoM...
I agree. It's not same SoM, but they are very similar with same circuit board.
> Anyway, I shared my opinion and I am not going to spend more time on
> this. It should not be my task to go through schematics and prove that
> PMICs differ. Authors should.
We will make it more clear in the description about PMIC difference.
Since we have the agreement that Hamoa/Purwa modules are very similar,
we will use common dtsi in next version. Please let me know if you think
that's not correct thing to do.
> Best regards,
> Krzysztof

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