Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752280AbaGJWgd (ORCPT ); Thu, 10 Jul 2014 18:36:33 -0400 Received: from mail-qa0-f51.google.com ([209.85.216.51]:60412 "EHLO mail-qa0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752030AbaGJWgb (ORCPT ); Thu, 10 Jul 2014 18:36:31 -0400 MIME-Version: 1.0 In-Reply-To: <20140710094758.GA6501@e106497-lin.cambridge.arm.com> References: <1404240214-9804-1-git-send-email-Liviu.Dudau@arm.com> <1404240214-9804-7-git-send-email-Liviu.Dudau@arm.com> <20140708005954.GC22939@google.com> <20140708104655.GC6501@e106497-lin.cambridge.arm.com> <20140708224847.GC4980@e106497-lin.cambridge.arm.com> <20140710094758.GA6501@e106497-lin.cambridge.arm.com> From: Bjorn Helgaas Date: Thu, 10 Jul 2014 16:36:10 -0600 Message-ID: Subject: Re: [PATCH v8 6/9] pci: Introduce a domain number for pci_host_bridge. To: Liviu Dudau Cc: linux-pci , Catalin Marinas , Will Deacon , Benjamin Herrenschmidt , Arnd Bergmann , linaro-kernel , Tanmay Inamdar , Grant Likely , Sinan Kaya , Jingoo Han , Kukjin Kim , Suravee Suthikulanit , LKML , Device Tree ML , LAKML Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 10, 2014 at 3:47 AM, Liviu Dudau wrote: > I don't see a way out of adding new PCI interfaces if we want to have support in > the PCI framework for unifying existing architectures. Of course, there is the painful > alternative of changing the existing APIs and fixing arches in one go, but like you've > said is going to be messy. I don't think I (or the people and companies wanting PCIe > on arm64) should cop out and pick a quick fix that adds sysdata structure into arm64 > just to avoid new APIs, as this is not going to help anyone in long term. What I can > do is to create a set of parallel APIs for pci_{scan,create}_root_bus() that take > a pci_host_bridge pointer and start converting architectures one by one to that API > while deprecating the existing one. That way we can add arm64 easily as it would be > the first architecture to use new code without breaking things *and* we provide a > migration path. A lot of the v7 discussion was about pci_register_io_range(). I apologize, because I think I really derailed things there and it was unwarranted. Arnd was right that migrating other arches should be a separate effort. I *think* I was probably thinking about the proposal of adding pci_create_root_bus_in_domain(), and my reservations about that got transferred to the pci_register_io_range() discussion. In any case, I'm completely fine with pci_register_io_range() now. Most of the rest of the v7 discussion was about "Introduce a domain number for pci_host_bridge." I think we should add arm64 using the existing pci_scan_root_bus() and keep the domain number in the arm64 sysdata structure like every other arch does. Isn't that feasible? We can worry about domain unification later. I haven't followed closely enough to know what other objections people had. Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/