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    SubjectRe: Workaround for Intel MPS errata
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    On Fri, Sep 30, 2011 at 2:03 AM, Rolf Eike Beer <eike-kernel@sf-tec.de> wrote:
    >> Hey Avi,
    >> Can you try this patch?  It should resolve the issue you are seeing.
    >>
    >> Thanks,
    >> Jon
    >>
    >>     PCI: Workaround for Intel MPS errata
    >>
    >>     Intel 5000 and 5100 series memory controllers have a known issue if
    >> read
    >>     completion coalescing is enabled (the default setting) and the PCI-E
    >>     Maximum Payload Size is set to 256B.  To work around this issue,
    >> disable
    >>     read completion coalescing if the MPS is 256B.
    >>
    >>     http://www.intel.com/content/dam/doc/specification-update/5000-chipset-memory-controller-hub-specification-update.pdf
    >>     http://www.intel.com/content/dam/doc/specification-update/5100-memory-controller-hub-chipset-specification-update.pdf
    >>
    >>     Reported-by: Avi Kivity <avi@redhat.com>
    >>     Signed-off-by: Jon Mason <mason@myri.com>
    >>
    >> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
    >> index a919db2..13c733a 100644
    >> --- a/drivers/pci/probe.c
    >> +++ b/drivers/pci/probe.c
    >> @@ -1361,6 +1361,80 @@ static int pcie_find_smpss(struct pci_dev *dev,
    >> void *data)
    >>       return 0;
    >>  }
    >>
    >> +static void pcie_errata_check(int mps)
    >> +{
    >
    > While this whole function is about Intel 5x00 devices the name of it is
    > very generic (and in a very generic file). Maybe this can be changed, e.g.

    I made it generic in naming because I'm betting there are other chips
    out there that don't play nice with others.

    > "fixup:" renamed to "fixup_intel_5x00:". Also I wonder if that shouldn't
    > be a nop when CONFIG_PCI_QUIRKS is not set.

    It probably should be a no-op for non-x86 too, as I doubt many other
    arches use Intel memory controllers (maybe IA64).

    Thanks,
    Jon

    >
    > Eike
    >
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