On Fri, 10 Sep 2010 12:20:36 -0700
Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On 09/10/2010 11:10 AM, Bjorn Helgaas wrote:
> > On Thursday, September 09, 2010 07:56:59 pm Yinghai Lu wrote:
> >>
> >> When bios switch to use Device object instead of Processor statement.
> >>
> >> the SSDT for Pstate/Cstate/Tstate can not be loaded dynamically.
> >>
> >> So try to scan ACPI0007 in addition to Processor.
> >>
> >> this fix regression: 2.6.32 is ok.
> >
> > Can you include the URL of the regression bug report? And maybe
> > the commit that introduced the regression?
>
> the commit should be
>
> commit d8191fa4a33fdc817277da4f2b7f771ff605a41c
> Author: Alex Chiang <achiang@xxxxxx>
> Date: Mon Feb 22 12:11:39 2010 -0700
>
> ACPI: processor: driver doesn't need to evaluate _PDC
>
> Now that the early _PDC evaluation path knows how to correctly
> evaluate _PDC on only physically present processors, there's no
> need for the processor driver to evaluate it later when it loads.
>
> To cover the hotplug case, push _PDC evaluation down into the
> hotplug paths.
>
> Cc: x86@xxxxxxxxxx
> Cc: Tony Luck <tony.luck@xxxxxxxxx>
> Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
> Signed-off-by: Alex Chiang <achiang@xxxxxx>
> Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
>
> that is between 2.6.34-rc1 and 2.6.34-rc2.
>
> So we need put this patch in stable tree for 2.6.34, .35, .36
>
Maybe. But first can you please address Bjorn's suggestions below?
>
> >
> >> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> >>
> >> ---
> >> drivers/acpi/processor_core.c | 1 +
> >> 1 file changed, 1 insertion(+)
> >>
> >> Index: linux-2.6/drivers/acpi/processor_core.c
> >> ===================================================================
> >> --- linux-2.6.orig/drivers/acpi/processor_core.c
> >> +++ linux-2.6/drivers/acpi/processor_core.c
> >> @@ -352,4 +352,5 @@ void __init acpi_early_processor_set_pdc
> >> acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
> >> ACPI_UINT32_MAX,
> >> early_init_pdc, NULL, NULL, NULL);
> >> + acpi_get_devices("ACPI0007", early_init_pdc, NULL, NULL);
> >
> > I hate having to walk the namespace. Usually that's a clue that
> > there's something wrong with our ACPI device model, because it'd
> > be better to handle everything in a driver .add() method. But
> > maybe this early _PDC thing is so special that it can't be helped
> > in this case.
> >
> > But I do think you could probably fix this to walk the namespace
> > once rather than twice. Maybe you could use something like
> > acpi_walk_namespace(ACPI_TYPE_ANY, ...) with a callback that
> > recognizes both ACPI_TYPE_PROCESSOR and "ACPI_TYPE_DEVICE with
> > HID ACPI0007".
> >
> > Bjorn
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