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Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors against platfrom specific quirks.

From Mark Salter <msalter@redhat.com>
Newsgroups linux.kernel
Subject Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors against platfrom specific quirks.
Date 2016-01-08 15:20 +0100
Message-ID <qOG3w-7SE-15@gated-at.bofh.it> (permalink)
References <qGm1X-3p8-11@gated-at.bofh.it> <qGm1Y-3p8-27@gated-at.bofh.it>
Organization Red Hat, Inc

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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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Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Mark Salter <msalter@redhat.com> - 2016-01-08 15:20 +0100
  Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Tomasz Nowicki <tn@semihalf.com> - 2016-01-08 15:40 +0100
    Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Mark Salter <msalter@redhat.com> - 2016-01-08 16:00 +0100
  Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Mark Rutland <mark.rutland@arm.com> - 2016-01-08 16:10 +0100
    Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Mark Rutland <mark.rutland@arm.com> - 2016-01-08 16:20 +0100
      Re: [PATCH V2 22/23] pci, acpi: Match PCI config space accessors  against platfrom specific quirks. Mark Salter <msalter@redhat.com> - 2016-01-08 17:10 +0100

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