On 17.02.2016 14:44, Jayachandran Chandrashekaran Nair wrote:

Tomasz, Lorenzo,

On Tue, Feb 16, 2016 at 7:23 PM, Tomasz Nowicki[off-list ref]  wrote:

quoted

quoted

As we now have valid PCI host bridge device reference we can
introduce code that is going to find its bus domain number using
ACPI _SEG method.

Note that _SEG method is optional, therefore _SEG absence means
that all PCI buses belong to domain 0.

While at it, for the sake of code clarity we put ACPI and DT domain
assign methods into the corresponding helpers.

In my patchset, I had a slightly different and I think better approach for
this without calling the _SEG method again. Please see
http://www.spinics.net/lists/arm-kernel/msg478167.html
at the last part ofhttp://www.spinics.net/lists/arm-kernel/msg478169.html

Relying on NULL parent device to make decision on boot method is really 
ugly way. This may hit us again once we want to obtain another firmware 
specific info e.g. numa node. IMO we need to fix it this way.

Tomasz