RE: acpi_cpufreq broken after _PDC patch

[Pallipadi, Venkatesh]

Please use Enhanced speedstep config option as well under Ppower
Management->cpufreq (with ACPI option under it enabled too). That will
configure speedstep-centrino driver, which should work here.
Speedstep-centrino driver is a better option than acpi-cpufreq, as it
will do much faster P-state transition.

Thanks,
Venki 

>-----Original Message-----
>From: Gerhard Schrenk [mailto:deb.gschrenk@xxxxxx] 
>Sent: Saturday, February 04, 2006 7:03 AM
>To: Pallipadi, Venkatesh
>Cc: linux-kernel@xxxxxxxxxxxxxxx
>Subject: acpi_cpufreq broken after _PDC patch
>
>Hi,
>
>commit 05131ecc99ea9da7f45ba3058fe8a2c1d0ceeab8 breaks acpi_cpufreq for
>an Intel Centrino notebook with Pentium M 1.60GHz (it's a Medion MD
>95600 (aka MSI S260) notebook).
>
>|gps@medusa:~/scratch/kernel-tree$ git bisect bad
>|05131ecc99ea9da7f45ba3058fe8a2c1d0ceeab8 is first bad commit
>|diff-tree 05131ecc99ea9da7f45ba3058fe8a2c1d0ceeab8 (from 
>d2149b542382bfc206cb28485108f6470c979566)
>|Author: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
>|Date:   Sun Oct 23 16:31:00 2005 -0400
>|
>|    [ACPI] Avoid BIOS inflicted crashes by evaluating _PDC only once
>|    
>|    Linux invokes the AML _PDC method (Processor Driver Capabilities)
>|    to tell the BIOS what features it can handle.  While the ACPI
>|    spec says nothing about the OS invoking _PDC multiple times,
>|    doing so with changing bits seems to hopelessly confuse the BIOS
>|    on multiple platforms up to and including crashing the system.
>|    
>|    Factor out the _PDC invocation so Linux invokes it only once.
>|    
>|    http://bugzilla.kernel.org/show_bug.cgi?id=5483
>|    
>|    Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx>
>|    Signed-off-by: Len Brown <len.brown@xxxxxxxxx>
>
>The error message is
>
>|gps@medusa:~$ sudo modprobe acpi_cpufreq
>|FATAL: Error inserting acpi_cpufreq
>|(/lib/modules/2.6.15-rc3-bisect1/kernel/arch/i386/kernel/cpu/c
pufreq/acpi-cpufreq.ko):
>|No such device
>
>Unfortunately 
>
>  git revert 05131ecc99ea9da7f45ba3058fe8a2c1d0ceeab8 
>
>does not work without merge conflict on top of Linus' tree.
>
>-- Gerhard
>
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