Re: [PATCH 1/2] dt-bindings: PCI: Add linux,pci-domain-reuse property

[Krzysztof Kozlowski <krzk@kernel.org>]

On 03/11/2026 03:57, Cui Chao wrote:
> 
> On 11/2/2026 6:00 PM, Krzysztof Kozlowski wrote:
>> On 02/11/2026 10:51, Cui Chao wrote:
>>> Add a new optional boolean property 'linux,pci-domain-reuse' for PCI
>>> host bridges.
>>>
>>> By default, the 'linux,pci-domain' property must be unique across all
>>> host bridges. This property allows a host bridge to explicitly opt-out
>>> of this uniqueness check, permitting multiple host bridges to reuse the
>>> same software domain number.
>> Why isn't this deducible from the compatibles?
> Hi Krzysztof,
> 
> Thanks.
> 
> The compatible cannot express this. "pci-host-ecam-generic" only

You have vendor specific compatibles, no?

> describes how configuration space is accessed; it does not describe
> whether two host bridge instances may share one Linux PCI domain.
> 
> The same compatible is used on systems where every host bridge must
> have a unique domain and on this system where two RCs intentionally
> share a domain with disjoint bus ranges and resource windows.
> Comparing the compatible strings of the nodes therefore cannot
> distinguish our case.

OK, so let's look at your DTS - where is it posted for upstream?

> 
> Adding a vendor-specific compatible only to trigger this Linux policy
> would not describe a different hardware programming model either.
> What actually makes reuse valid is the platform-level relationship:
> the bus ranges and resource windows are disjoint.
> 
> If you prefer to avoid a new property, I can rework this to derive or
> validate reuse from the non-overlapping bus-range and resource layout
> instead. Would that be the preferred direction?
> 

This one is clear paste of LLM output to a message.


Best regards,
Krzysztof