Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758909AbbFCMtt (ORCPT ); Wed, 3 Jun 2015 08:49:49 -0400 Received: from foss.arm.com ([217.140.101.70]:39541 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752416AbbFCMtj (ORCPT ); Wed, 3 Jun 2015 08:49:39 -0400 Date: Wed, 3 Jun 2015 13:49:41 +0100 From: Lorenzo Pieralisi To: Jiang Liu Cc: "hanjun.guo@linaro.org" , "Rafael J . Wysocki" , Bjorn Helgaas , Marc Zyngier , Liviu Dudau , Yijing Wang , Catalin Marinas , Will Deacon , Lv Zheng , "lenb @ kernel . org" , LKML , "linux-pci@vger.kernel.org" , "linux-acpi@vger.kernel.org" , "x86 @ kernel . org" , "linux-arm-kernel@lists.infradead.org" , Arnd Bergmann Subject: Re: [Patch v4 5/8] ARM64/PCI/ACPI: Introduce struct pci_controller for ACPI Message-ID: <20150603124940.GA28247@red-moon> References: <1433225576-8215-1-git-send-email-jiang.liu@linux.intel.com> <1433225576-8215-6-git-send-email-jiang.liu@linux.intel.com> <20150602093525.GA23543@red-moon> <556EBE6D.90907@linaro.org> <556ECA93.7040800@linux.intel.com> <20150603100343.GA27917@red-moon> <556ED51C.4070302@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <556ED51C.4070302@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5488 Lines: 126 On Wed, Jun 03, 2015 at 11:21:16AM +0100, Jiang Liu wrote: > On 2015/6/3 18:03, Lorenzo Pieralisi wrote: > > On Wed, Jun 03, 2015 at 10:36:19AM +0100, Jiang Liu wrote: > >> On 2015/6/3 16:44, Hanjun Guo wrote: > >>> On 2015???06???02??? 17:35, Lorenzo Pieralisi wrote: > >>>> On Tue, Jun 02, 2015 at 07:12:53AM +0100, Jiang Liu wrote: > >>>>> From: Hanjun Guo > >>>>> > >>>>> ARM64 ACPI based PCI host bridge init needs a arch dependent > >>>>> struct pci_controller to accommodate common PCI host bridge > >>>>> code which is introduced later, or it will lead to compile > >>>>> errors on ARM64. > >>>>> > >>>>> Signed-off-by: Hanjun Guo > >>>>> Tested-by: Suravee Suthikulpanit > >>>>> CC: Arnd Bergmann > >>>>> CC: Catalin Marinas > >>>>> CC: Liviu Dudau > >>>>> CC: Lorenzo Pieralisi > >>>>> CC: Will Deacon > >>>>> Signed-off-by: Jiang Liu > >>>>> --- > >>>>> arch/arm64/include/asm/pci.h | 10 ++++++++++ > >>>>> 1 file changed, 10 insertions(+) > >>>>> > >>>>> diff --git a/arch/arm64/include/asm/pci.h b/arch/arm64/include/asm/pci.h > >>>>> index b008a72f8bc0..70884957f253 100644 > >>>>> --- a/arch/arm64/include/asm/pci.h > >>>>> +++ b/arch/arm64/include/asm/pci.h > >>>>> @@ -10,6 +10,16 @@ > >>>>> #include > >>>>> #include > >>>>> > >>>>> +struct acpi_device; > >>>>> + > >>>>> +struct pci_controller { > >>>>> +#ifdef CONFIG_ACPI > >>>>> + struct acpi_device *companion; /* ACPI companion device */ > >>>>> +#endif > >>>>> + int segment; /* PCI domain */ > >>>>> + int node; /* NUMA node */ > >>>>> +}; > >>>> > >>>> There is nothing ARM64 specific in this structure. The only > >>>> reason I see you want to keep it arch specific is the iommu > >>>> pointer on x86, > >>> > >>> And also plarform_data for IA64 too. > >>> > >>>> but I think we should find a way to make > >>>> the common bits shared across archs (ie the struct above) and > >>>> add (maybe a void*) to the generic struct to cater for arch > >>>> specific data. > >>>> > >>>> Thoughts ? > >>> > >>> We discussed this already, it has limitations to make it > >>> common to all archs, I think the limitation are: > >>> > >>> - struct pci_controller are also used for other archs > >>> such as PowerPC and Tile, they will not use it for > >>> ACPI purpose, so we can not used for all archs. > >>> > >>> - if we let struct pci_controller defined only for archs > >>> using ACPI, such as introduce it in linux/acpi.h, we still > >>> can not satisfy that the struct pci_controller is not > >>> only used for ACPI case on x86, it will be used for > >>> non-ACPI too. > >>> > >>> So it's pretty difficult to share it with across archs to me, > >>> any more ideas? > >> Hi Hanjun and Lorenzo, > >> As mentioned by Hanjun, I have no idea yet about how to > >> consolidating "struct pci_controller" further. One possible > >> way is to move "struct pci_controller" related code into > >> arch, but apparently that will reduce code reusing. > > > > I guess you can't move that struct pci_controller to generic code > > since it is present on other archs too (with completely different > > members). > > > > What you can do is creating a new struct (ie same purpose of pci_controller > > with a different name) common to all archs that contains the common bits > > + a void* data that contains arch specific data, and convert x86 and ia64 > > to using it. > > > > It is weird to be forced to declare a pci_controller structure in arm64 > > code with 0 arch specific data in it. > > Hi Lorenzo, > I have thought to consolidate pci_controller for x86 and ia64, > but that will make the change set much more bigger. How about to > consolidate pci_controller by another patch set. That will be easier > for review. Agreed, but with this set you are forcing arm64 to define pci_controller as pci_bus sysdata and I am not really keen on that, there are already function calls in the arm64 pci layer that are there to make ACPI compile and it is a bit annoying, instead of removing them we are adding arch stuff on top. How about passing a void* pointer (ie that is what pci_create_root_bus expects) to acpi_pci_root_create through a member in acpi_pci_root_info (I mean acpi_pci_root_info replaces the controller member with a void* where you can add x86/ia64 pci_controller) ? I understand this forces you to alloc the pci_controller in arch code, but that's not a big deal right ? This way you can drop the pci_controller struct from arm64 (I do not even know if it will ever be needed, by looking at Hanjun's code, the bits of code that need the pci_controller can be moved to generic PCI layer). https://lkml.org/lkml/2015/5/26/215 This way we can add the generic struct we discussed later (pci_controller refactoring), I agree it is going to be a bigger change but at least you do not force something into arm64 that we do not even know if it is required. Thanks anyway for putting this series together. Lorenzo -- 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/