Re: [PATCH] PCI: add missing DT binding for linux,pci-domain property

[Arnd Bergmann <arnd@arndb.de>]

On Tuesday 04 November 2014 12:00:52 Liviu Dudau wrote:
> 
> While the description is potentially correct, what it fails to explain is that the
> choice of using the property or generating an unstable (across boots) unique
> number is actually the choice of the host bridge driver at the moment. I know that
> my earlier implementations were defaulting to the automatic numbering, but that has
> been dropped from the final series as Rob Herring was objecting to it.
> 
> There is still scope to adopt a wide policy here, but for now it should say something
> to the tune:
> 
>    If present this property assigns a fixed PCI domain number to a host bridge,
>    otherwise an unstable (across boots) unique number will be assigned.
>    If you decide to use the property to assign a fixed PCI domain number to a host
>    bridge you have to ensure that all the host bridge drivers present in the system
>    follow the same policy. Otherwise, potentially conflicting domain numbers
>    may be assigned to root busses behind different host bridges.

But with the latest change to the domain handling, all drivers would implement
this. I would just mention that Linux kernels older than 3.19 are probably
going to ignore this property.

	Arnd