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    SubjectRe: [git pull] PCI changes
    On Fri, Jan 13, 2012 at 03:14:21PM -0800, Linus Torvalds wrote:
    > On Fri, Jan 13, 2012 at 1:24 PM, Matthew Garrett <> wrote:
    > >>
    > >> So why is acpi_pci_root_add() special? Cna you explain that part to me?
    > >
    > > pcie_no_aspm() means "Do not permit ASPM to be enabled" - it doesn't
    > > alter the existing state. pcie_clear_aspm() does that.
    > I *know*.
    > So look again.
    > Why is acpi_pci_root_add() special?
    > Because dammit, it does exactly that pcie_clear_aspm() for the
    > ACPI_FADT_NO_ASPM case.

    I'm sorry, I thought you were referring to the status quo rather than
    the patch - I see what you mean now. The intent here is to clear ASPM
    state if the FADT bit has been set *and* we've got _OSC control, whereas
    previously we'd clear ASPM state any time the FADT bit was set. There
    are some machines which (a) set the FADT bit, (b) hand over _OSC
    control, (c) program the device and (d) crash under certain
    circumstances if you then try to use it. My assumption here is that the
    FADT bit *does* mean "clear ASPM state", but only if we've been granted
    _OSC control. That's the behaviour described in the changelog.

    Matthew Garrett |

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