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Message-ID: <1452262581.31901.26.camel@redhat.com>
Date: Fri, 08 Jan 2016 09:16:21 -0500
From: Mark Salter <msalter@...hat.com>
To: Tomasz Nowicki <tn@...ihalf.com>, bhelgaas@...gle.com,
arnd@...db.de, will.deacon@....com, catalin.marinas@....com,
rjw@...ysocki.net, hanjun.guo@...aro.org,
Lorenzo.Pieralisi@....com, okaya@...eaurora.org,
jiang.liu@...ux.intel.com, Stefano.Stabellini@...citrix.com
Cc: robert.richter@...iumnetworks.com, mw@...ihalf.com,
Liviu.Dudau@....com, ddaney@...iumnetworks.com, tglx@...utronix.de,
wangyijing@...wei.com, Suravee.Suthikulpanit@....com,
linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
linaro-acpi@...ts.linaro.org, jchandra@...adcom.com, jcm@...hat.com
Subject: Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors
against platfrom specific quirks.
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 accessors
> set before PCI buses enumeration. Algorithm that overwrite accessors
> matches against platform ID (DMI), domain and bus number, hopefully
> enough for all cases. All quirks can be defined using:
> DECLARE_ACPI_MCFG_FIXUP() and keep self contained.
>
> example:
>
> static const struct dmi_system_id yyy[] = {
> {
> .ident = "<Platform ident string>",
> .callback = <handler>,
> .matches = {
> DMI_MATCH(DMI_SYS_VENDOR, "<system vendor>"),
> DMI_MATCH(DMI_PRODUCT_NAME, "<product name>"),
> DMI_MATCH(DMI_PRODUCT_VERSION, "product version"),
> },
> },
> { }
> };
>
This seems awkward to me in the case where the quirk is SoC-based and there
may be multiple platforms affected. Needing a DECLARE_ACPI_MCFG_FIXUP 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 possibly
some SoC register to cover all platforms affected.
Also, there doesn't seem to be a way to connect a given quirk check to the
MCFG/device requesting the ops. So if there is a platform with multiple PCIE
roots and not all of them have quirks, how does one no whether to override the
default ecam ops?
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