From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161132AbcFBPTi (ORCPT ); Thu, 2 Jun 2016 11:19:38 -0400 Received: from mout.kundenserver.de ([212.227.126.134]:65533 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932892AbcFBPTg (ORCPT ); Thu, 2 Jun 2016 11:19:36 -0400 From: Arnd Bergmann To: Tomasz Nowicki Cc: linux-arm-kernel@lists.infradead.org, rafael@kernel.org, linux-pci@vger.kernel.org, will.deacon@arm.com, okaya@codeaurora.org, wangyijing@huawei.com, andrea.gallo@linaro.org, Lorenzo.Pieralisi@arm.com, linaro-acpi@lists.linaro.org, ddaney@caviumnetworks.com, linux-acpi@vger.kernel.org, robert.richter@caviumnetworks.com, helgaas@kernel.org, liudongdong3@huawei.com, catalin.marinas@arm.com, Liviu.Dudau@arm.com, jcm@redhat.com, msalter@redhat.com, cov@codeaurora.org, mw@semihalf.com, jchandra@broadcom.com, dhdang@apm.com, linux-kernel@vger.kernel.org, jeremy.linton@arm.com, hanjun.guo@linaro.org, Suravee.Suthikulpanit@amd.com Subject: Re: [RFC PATCH 1/3] pci, acpi: Match PCI config space accessors against platfrom specific ECAM quirks. Date: Thu, 02 Jun 2016 17:19:13 +0200 Message-ID: <4608372.hbXNF1lbNO@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-22-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <57503626.9050208@semihalf.com> References: <1464856864-18049-1-git-send-email-tn@semihalf.com> <9294389.sZPDtyjoUs@wuerfel> <57503626.9050208@semihalf.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:/6MKBpwS/kIjN7ZorOd35B21+9HOHR7OfE+1/wqZrW3XReRSMHG GQgoQDHwlKlsgzIpM/L14z0/VAkrTgXrPf7GjdcmBZO2R+LDHEPMmzYAocje265lcR+XlfB 2FLqS7L5fj01Ok9NomLOMRNyUwzowsxtL+XsJbnuMcptXppJlpMAoCC17B542pT0UvsixCN OhoqfapYrFfjR3+pWt3Qw== X-UI-Out-Filterresults: notjunk:1;V01:K0:96eLaW46d4k=:6eXOfUz7JwdcSVvqB3dWGr h8KpkC7Oz3Sn2uEx+KrmN+EyDp125C7qO2m3ZCFnnC7Uj59CTHWgLGKTaEKZ0d7/yIrv+IMSv FZQe5DSV3/qWVrWxxb1eqMliC9A+28pGTohtbhpcpis6KFzzEFsOCqZORCtgR2zWwc6dyo+j4 gmpQxO6fteW9Am3e6aRt1AZYloKrSrcMSoMydOZyzBwyVclDx2DQWssoiKRyPFIM7Gr1QWDNT xc9aTPxHJ8rK6M1Gks743b8/suc7dyRWqseEszPZx4BSOrtWOYdeaTQRckerK1Q2HmEbEPN5/ ybW/1OgIeeKVorQ9PTWPTyvW9QDSFF2x0RihL3dh/IFlWjQJz6ng7iS2ipC6av3CAZR2ve78K yNPmxfTzzAsLuwogpDOzvP1JI2IKhUQUrawnLYt5sy98T4c/s30F60ya80G3JAz/QXVC7dlSX 8StaSyZNbDI06X6T4k1Q6TPc8jcRI+fhd2/t3foKHxNxs9yTxO9zK64v+H7knO8Igcm7JpEUN zB3Un9+K3uyuVOacnYCrVHAH8nfYHl5eSnRTRsjOxVrjahJAP4BOX83AfCc6N4yfGhZANHl20 mAtGwnc0b2VkUdqn+dZmq5t07pKpkxXVo+hEVU/Wp96XHdatGxnn2f0B+sGfvW1BpENCakhVB wwMTSw/NHIIjDuiBteEGEm64f9BbCtpdITdI5ihnwNJxHY5z94zeAj5xNr/EYWoNhYZ20vzuu GeXtNpkPj3g0MY9t Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, June 2, 2016 3:35:34 PM CEST Tomasz Nowicki wrote: > On 02.06.2016 14:32, Arnd Bergmann wrote: > > On Thursday, June 2, 2016 2:07:43 PM CEST Tomasz Nowicki wrote: > >> On 02.06.2016 13:42, Arnd Bergmann wrote: > >>> On Thursday, June 2, 2016 10:41:01 AM CEST Tomasz Nowicki wrote: > >>>> +struct pci_ecam_ops *pci_mcfg_get_ops(struct acpi_pci_root *root) > >>>> +{ > >>>> + int bus_num = root->secondary.start; > >>>> + int domain = root->segment; > >>>> + struct pci_cfg_fixup *f; > >>>> + > >>>> + if (!mcfg_table) > >>>> + return &pci_generic_ecam_ops; > >>>> + > >>>> + /* > >>>> + * Match against platform specific quirks and return corresponding > >>>> + * CAM ops. > >>>> + * > >>>> + * First match against PCI topology then use OEM ID and > >>>> + * OEM revision from MCFG table standard header. > >>>> + */ > >>>> + for (f = __start_acpi_mcfg_fixups; f < __end_acpi_mcfg_fixups; f++) { > >>>> + if ((f->domain == domain || f->domain == PCI_MCFG_DOMAIN_ANY) && > >>>> + (f->bus_num == bus_num || f->bus_num == PCI_MCFG_BUS_ANY) && > >>>> + (!strncmp(f->oem_id, mcfg_table->header.oem_id, > >>>> + ACPI_OEM_ID_SIZE)) && > >>>> + (f->oem_revision == mcfg_table->header.oem_revision)) > >>>> + return f->ops; > >>>> + } > >>>> + /* No quirks, use ECAM */ > >>>> + return &pci_generic_ecam_ops; > >>>> +} > >>>> + > >>>> int pci_mcfg_lookup(struct acpi_pci_root *root) > >>> > >>> Can you explain the use of pci_ecam_ops instead of pci_ops here? > >>> > >> > >> I wanted to get associated bus_shift and use it to setup configuration > >> region properly before calling pci_ecam_create. Please see next patch. > >> > > > > I see. It feels really odd to do it this way though, since having a > > nonstandard bus_shift essentially means not using anything resembling > > ECAM to start with. > > > > I realize that a lot of the host bridges are not ECAM, but because > > of this, it would be more logical to have their own pci_ops instead > > of pci_ecam_ops. > > Well, we have bus_shift there to express bus shift differentiation. So I > would say we should change just structure name to prevent misunderstanding. I'm not really convinced here. We use the bus_shift for two completely different things in the end: for sizing the MMIO window that gets mapped by ACPI and for the pci_ecam_map_bus() function that isn't actually used for the typical fixups that override the pci_ops. I see now that this sneaks in an .init callback for the quirk through the backdoor, by adding it to the pci_ecam_ops. I think that is not good: if the idea is to have the config space access be adapted to various quirks that is one thing, but if we actually need a function to be called for the quirk we should do just that and have it be obvious. That function can then override the pci_ops. Arnd