Re: [PATCH 1/3] dt-bindings: arm: rockchip: Add ArmSoM Sige7s

[Quentin Schulz <quentin.schulz@cherry.de>]

Hi Jianfeng Liu,

On 10/27/26 3:28 AM, Jianfeng Liu wrote:
> Hi Heiko,
> 
> On 2026-10-26 11:43 UTC, Heiko Stuebner wrote:
>>> I confirmed this with ArmSoM. They purchased the original CoolPi 4B
>>> hardware design from CoolPi and confirmed that no hardware design
>>> modifications were made for the Sige7s.
>>>
>>> So the Sige7s uses the same hardware design as the CoolPi 4B, rather
>>> than being independently designed.
>>
>> if it's the completely same board, just with a different print on
>> the board, why does it need an empty devicetree. When it's completely
>> unchanged, what's speaking against just re-using the original one?
> 
> The existing CoolPi 4B DTB does work on the Sige7s, and I agree that there
> is no hardware difference requiring a separate device tree.
> 
> My main reason for adding a separate DTS is to preserve the Sige7s board
> identity for long-term upstream support.
> 
> The CoolPi 4B appears to be discontinued and is no longer readily available
> through the purchase channels listed on its official website
> (https://www.cool-pi.com/buy/). In contrast, ArmSoM is actively selling the
> Sige7s and has committed to producing it until at least January 2034.
> 
> I'm also planning to add mainline U-Boot support for the Sige7s and
> integrate it with Stubble-based UEFI booting.
> 

I am not sure I want this in U-Boot. Why should we have add a defconfig 
(and thus increase the CI build time) for a device that's already 
entirely covered by another defconfig? I guess the Linux kernel doesn't 
care about this so we don't need to discuss this here.

> While U-Boot could update the model and compatible properties before
> booting Linux, Stubble may replace the firmware-provided DTB with one
> bundled with the kernel. Having a Sige7s-specific DTB would preserve the
> correct board identity throughout this process without requiring additional
> distribution-specific modifications.
> 

 From U-Boot's perspective, I would have preferred there be a simple 
difference we can detect at runtime and based on that decide which 
device tree to load between coolpi-4b and armsom-sige7s.

> This would also avoid confusing users who purchase a Sige7s but find their
> system identified as a CoolPi 4B.
> > The shared dtsi ensures that we do not duplicate the hardware 
description,
> with the two board DTS files differing only in model and compatible.
> 

I don't know Heiko's or Krzysztof's opinion here, but I think it would 
better reflect the actual context to NOT use a dtsi and simply have 
arch/arm64/boot/dts/rockchip/rk3588s-armsom-sige7s.dts include 
arch/arm64/boot/dts/rockchip/rk3588s-coolpi-4b.dts and update the model 
and compatible properties.

Cheers,
Quentin