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acpi-cpufreq: Add support for disabling dynamic overclocking

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One feature present in powernow-k8 that isn't present in acpi-cpufreq
is support for enabling or disabling AMD's core performance boost
technology. This patch adds support to acpi-cpufreq, but also
includes support for Intel's dynamic acceleration.

The original boost disabling sysfs file was per CPU, but acted
globally. Also the naming (cpb) was at least not intuitive.
So lets introduce a single file simply called "boost", which sits
once in /sys/devices/system/cpu/cpufreq.
This should be the only way of using this feature, so add
documentation about the rationale and the usage.

A following patch will re-introduce the cpb knob for compatibility
reasons on AMD CPUs.

Per-CPU boost switching is possible, but not trivial and is thus
postponed to a later patch series.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
This commit is contained in:
Andre Przywara
2012-09-04 08:28:07 +00:00
committed by Rafael J. Wysocki
parent f594065faf
commit 615b730071
3 changed files with 281 additions and 0 deletions
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11
Documentation/ABI/testing/sysfs-devices-system-cpu
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@@ -176,3 +176,14 @@ Description: Disable L3 cache indices
All AMD processors with L3 caches provide this functionality.
For details, see BKDGs at
http://developer.amd.com/documentation/guides/Pages/default.aspx
What: /sys/devices/system/cpu/cpufreq/boost
Date: August 2012
Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
Description: Processor frequency boosting control
This switch controls the boost setting for the whole system.
Boosting allows the CPU and the firmware to run at a frequency
beyound it's nominal limit.
More details can be found in Documentation/cpu-freq/boost.txt