From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v7 4/6] pci: Introduce a domain number for pci_host_bridge. Date: Wed, 09 Apr 2014 16:08:43 +0200 Message-ID: <5040304.p3jyCMi26Y@wuerfel> References: <1394811272-1547-1-git-send-email-Liviu.Dudau@arm.com> <20140409120750.GN985@e106497-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: In-Reply-To: Sender: linux-pci-owner@vger.kernel.org To: Bjorn Helgaas Cc: Benjamin Herrenschmidt , linux-pci , Catalin Marinas , Will Deacon , linaro-kernel , LKML , "devicetree@vger.kernel.org" , LAKML , Tanmay Inamdar , Grant Likely List-Id: devicetree@vger.kernel.org On Wednesday 09 April 2014 08:02:41 Bjorn Helgaas wrote: > > It's possible we could manage domain numbers in the core. On ACPI > systems, we currently we use the ACPI _SEG value as the domain. In > some cases, e.g., on ia64, config space access is done via firmware > interfaces, and those interfaces expect the _SEG values. We could > conceivably maintain a mapping between _SEG and domain, but I'm not > sure there's an advantage there. I think it's a safe assumption that we will never have more than one firmware trying to enumerate the domains, so it would be safe to let ACPI keep doing its own thing for domain numbers, have the DT code pick domain number using some method we come up with, and for everything else let the architecture code deal with it. There are probably very few systems that have multiple domains but use neither ACPI nor DT. Arnd