From mboxrd@z Thu Jan 1 00:00:00 1970 From: "liudongdong (C)" Subject: Re: [PATCH V3 20/21] pci, acpi: Match PCI config space accessors against platfrom specific quirks. Date: Tue, 19 Jan 2016 16:52:25 +0800 Message-ID: <569DF949.5080208@huawei.com> References: <1452691267-32240-1-git-send-email-tn@semihalf.com> <1452691267-32240-21-git-send-email-tn@semihalf.com> <1452785776.28109.22.camel@redhat.com> <569CDD8F.807@semihalf.com> <569D9634.3040304@huawei.com> <569DEBE9.5090909@semihalf.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <569DEBE9.5090909@semihalf.com> Sender: linux-pci-owner@vger.kernel.org To: Tomasz Nowicki , Mark Salter , bhelgaas@google.com, arnd@arndb.de, will.deacon@arm.com, catalin.marinas@arm.com, rjw@rjwysocki.net, hanjun.guo@linaro.org, Lorenzo.Pieralisi@arm.com, okaya@codeaurora.org, jiang.liu@linux.intel.com, Stefano.Stabellini@eu.citrix.com Cc: robert.richter@caviumnetworks.com, mw@semihalf.com, Liviu.Dudau@arm.com, ddaney@caviumnetworks.com, tglx@linutronix.de, wangyijing@huawei.com, Suravee.Suthikulpanit@amd.com, linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org, linaro-acpi@lists.linaro.org, jchandra@broadcom.com, jcm@redhat.com, Zhou Wang , Gabriele Paoloni List-Id: linux-acpi@vger.kernel.org =E5=9C=A8 2016/1/19 15:55, Tomasz Nowicki =E5=86=99=E9=81=93: > On 19.01.2016 02:49, liudongdong (C) wrote: >> Hi Tomasz, Mark >> >> =E5=9C=A8 2016/1/18 20:41, Tomasz Nowicki =E5=86=99=E9=81=93: >>> On 14.01.2016 16:36, Mark Salter wrote: >>>>> +extern struct pci_mcfg_fixup __start_acpi_mcfg_fixups[]; >>>>> >+extern struct pci_mcfg_fixup __end_acpi_mcfg_fixups[]; >>>>> >+ >>>>> >+static struct pci_ops *pci_mcfg_check_quirks(struct acpi_pci_ro= ot >>>>> *root) >>>>> >+{ >>>>> >+ struct pci_mcfg_fixup *f; >>>>> >+ int bus_num =3D root->secondary.start; >>>>> >+ int domain =3D root->segment; >>>>> >+ >>>>> >+ /* >>>>> >+ * First match against PCI topology then use D= MI or >>>>> >+ * custom match handler. >>>>> >+ */ >>>>> >+ for (f =3D __start_acpi_mcfg_fixups; f < __end_acpi_mcfg_fi= xups; >>>>> f++) { >>>>> >+ if ((f->domain =3D=3D domain || f->domain =3D=3D >>>>> PCI_MCFG_DOMAIN_ANY) && >>>>> >+ (f->bus_num =3D=3D bus_num || f->bus_num =3D=3D >>>>> PCI_MCFG_BUS_ANY) && >>>>> >+ (f->system ? dmi_check_system(f->system) : 0 || >>>>> >+ f->match ? f->match(f, root) : 0)) >>>>> >+ return f->ops; >>>> I think this would be better as: >>>> >>>> (f->system ? dmi_check_system(f->system) : 1 && >>>> f->match ? f->match(f, root) : 1)) >>>> return f->ops; >>>> >>>> Otherwise, one has to call dmi_check_system() from f->match() if >>>> access to root is needed. >>> >> >> Non-DMI, we need not to call dmi_check_system() from f->match(), >> we can use _HID to decide to hook the pci_ops or not. > > Sorry, but I dont understand your point. Can you elaborate? > > With Mark modification, you can use the following cases to identify p= latform: > 1. DMI only > 2. f->match() only (_HID can be used there) > 3. DMI and f->match() > > DMI used to be very convenient way to recognise platform, sometimes i= t is not enough, hence f->match() alternative. > Yes, you are right, I was wrong. In my case, I can use the second point. 2. f->match() only (_HID can be used there) Thanks Dongdong > Tomasz > > > > . >