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Date: Tue, 7 Oct 2014 16:27:44 +0200
From: Robert Richter <robert.richter@caviumnetworks.com>
To: Arnd Bergmann <arnd@arndb.de>, Liviu Dudau <liviu.dudau@arm.com>
CC: <linux-arm-kernel@lists.infradead.org>,
	Robert Richter <rric@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Rob Herring <robh+dt@kernel.org>,
	Pawel Moll <pawel.moll@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Ian Campbell <ijc+devicetree@hellion.org.uk>,
	Kumar Gala <galak@codeaurora.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	<devicetree@vger.kernel.org>, <linux-pci@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, Sunil Goutham <sgoutham@cavium.com>
Subject: Re: [PATCH 3/6] pci, thunder: Add PCIe host controller devicetree
 bindings
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On 24.09.14 18:06:04, Arnd Bergmann wrote:
> > +               compatible = "cavium,thunder-pcie";
> > +               device_type = "pci";
> > +               msi-parent = <&its>;
> > +               bus-range = <0 255>;
> > +               #size-cells = <2>;
> > +               #address-cells = <3>;
> > +               reg = <0x8480 0x00000000 0 0x10000000>;  /* Configuration space */
> > +               ranges = <0x03000000 0x8010 0x00000000 0x8010 0x00000000 0x70 0x00000000>, /* mem ranges */
> > +                       <0x03000000 0x8300 0x00000000 0x8300 0x00000000 0x80 0x00000000>,
> > +                       <0x03000000 0x87e0 0x00000000 0x87e0 0x00000000 0x01 0x00000000>;
> > +        };
> 
> If you claim the entire 0-255 bus range, I think you should also
> specify a domain, otherwise it's not predictable which domain you
> get.

Liviu's code assigns a unique id to the domain if missing, see
of_pci_get_domain_nr(). So I don't think we need to add a "pci-domain"
property here.

Liviu's DT implementation that assigns a unique number differs a bit
from ACPI which states: "If _SEG [aka domain number] does not exist,
OSPM assumes that all PCI bus segments are in PCI Segment Group 0."

Maybe of_pci_get_domain_nr() should be similar to ACPI. If there are
multiple root bridges, the "pci-domain" property could be forced
instead.

-Robert