Messages in this thread | | | Date | Tue, 22 Jun 2010 11:29:08 -0700 | From | Jesse Barnes <> | Subject | Re: [PATCH] ACPI: Disable ASPM if the platform won't provide _OSC control for PCIe |
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On Tue, 22 Jun 2010 20:17:29 +0200 "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
> On Tuesday, June 22, 2010, Matthew Garrett wrote: > > The PCI SIG documentation for the _OSC OS/firmware handshaking interface > > states: > > > > "If the _OSC control method is absent from the scope of a host bridge > > device, then the operating system must not enable or attempt to use any > > features defined in this section for the hierarchy originated by the host > > bridge." > > > > The obvious interpretation of this is that the OS should not attempt to use > > PCIe hotplug, PME or AER - however, the specification also notes that an > > _OSC method is *required* for PCIe hierarchies, and experimental validation > > with An Alternative OS indicates that it doesn't use any PCIe functionality > > if the _OSC method is missing. That arguably means we shouldn't be using > > MSI or extended config space, but right now our problems seem to be limited > > to vendors being surprised when ASPM gets enabled on machines when other > > OSs refuse to do so. So, for now, let's just disable ASPM if the _OSC > > method doesn't exist or refuses to hand over PCIe capability control. > > > > Signed-off-by: Matthew Garrett <mjg@redhat.com> > > Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Applied to my linux-next branch, thanks.
-- Jesse Barnes, Intel Open Source Technology Center
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