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

[Cui Chao <cuichao1753@phytium.com.cn>]

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
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.

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?

-- 
Best regards,
Cui Chao.