From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors against platfrom specific quirks. Date: Fri, 8 Jan 2016 15:12:17 +0000 Message-ID: <20160108151216.GJ3097@leverpostej> References: <1450278993-12664-1-git-send-email-tn@semihalf.com> <1450278993-12664-23-git-send-email-tn@semihalf.com> <1452262581.31901.26.camel@redhat.com> <20160108150137.GH3097@leverpostej> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <20160108150137.GH3097@leverpostej> Sender: linux-pci-owner@vger.kernel.org To: Mark Salter Cc: linaro-acpi@lists.linaro.org, linux-pci@vger.kernel.org, will.deacon@arm.com, okaya@codeaurora.org, wangyijing@huawei.com, Lorenzo.Pieralisi@arm.com, Tomasz Nowicki , ddaney@caviumnetworks.com, linux-acpi@vger.kernel.org, robert.richter@caviumnetworks.com, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, arnd@arndb.de, Stefano.Stabellini@eu.citrix.com, Liviu.Dudau@arm.com, bhelgaas@google.com, tglx@linutronix.de, mw@semihalf.com, jcm@redhat.com, jchandra@broadcom.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, hanjun.guo@linaro.org, Suravee.Suthikulpanit@amd.com, jiang.liu@linux.intel.com List-Id: linux-acpi@vger.kernel.org On Fri, Jan 08, 2016 at 03:01:37PM +0000, Mark Rutland wrote: > On Fri, Jan 08, 2016 at 09:16:21AM -0500, Mark Salter wrote: > > On Wed, 2015-12-16 at 16:16 +0100, Tomasz Nowicki wrote: > > > Some platforms may not be fully compliant with generic set of PCI= config > > > accessors. For these cases we implement the way to overwrite acce= ssors > > > set before PCI buses enumeration. Algorithm that overwrite access= ors > > > matches against platform ID (DMI), domain and bus number, hopeful= ly > > > enough for all cases. All quirks can be defined using: > > > DECLARE_ACPI_MCFG_FIXUP() and keep self contained. > > >=20 > > > example: > > >=20 > > > static const struct dmi_system_id yyy[] =3D { > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0.ident =3D "", > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0.callback =3D , > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0.matches =3D { > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0DMI_MATCH(DMI_SYS_VENDOR, ""), > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0DMI_MATCH(DMI_PRODUCT_NAME, ""), > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0DMI_MATCH(DMI_PRODUCT_VERSION, "product version"), > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0}, > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0}, > > > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0{ } > > > }; > > >=20 > >=20 > > This seems awkward to me in the case where the quirk is SoC-based a= nd there > > may be multiple platforms affected. Needing a DECLARE_ACPI_MCFG_FIX= UP for > > each platform using such a SoC (i.e. Mustang and Moonshot) doesn't = seem > > right. In that case, I think it'd be better to check CPUID and poss= ibly > > some SoC register to cover all platforms affected. >=20 > CPUs get reused across SoCs, so as you've implicitly noted, the CPUID > alone is insufficient. >=20 > Given that IP blocks get moved around between SoC variants, I don't > think you can check "some SoC register" based on the CPU ID -- you ca= n > end up bringing the board down at that point. >=20 > If the CPU ID alone is insufficient to tell you about a component, it > cannot give you enough information about a component you can use to > query more information from. >=20 > If your platform requires a quirk, it's always going to be painful (a= nd > to some extent, rightfulyl so). We should aim for correctness here wi= th > explicit matching. =46urther, if there is going to be an ever-expanding set of platforms requring quirks, then we need a standard mechanism in ACPI to enable th= e platform to tell us explicitly either which specific PCI implementation is used, or which common quirk is necessary. Thanks, Mark.