Commit Graph

85 Commits

Author SHA1 Message Date
Rafael J. Wysocki 15d4cb9013 Merge branch 'pm-cpufreq'
* pm-cpufreq:
  intel_pstate: skip the driver if ACPI has power mgmt option
  cpufreq: ondemand: Remove redundant return statement
  cpufreq: move freq change notifications to cpufreq core
  cpufreq: distinguish drivers that do asynchronous notifications
  cpufreq/intel_pstate: Add static declarations to internal functions
  cpufreq: arm_big_little: reconfigure switcher behavior at run time
  cpufreq: arm_big_little: add in-kernel switching (IKS) support
  ARM: vexpress/TC2: register vexpress-spc cpufreq device
  cpufreq: arm_big_little: add vexpress SPC interface driver
  ARM: vexpress/TC2: add cpu clock support
  ARM: vexpress/TC2: add support for CPU DVFS
2013-11-07 19:26:02 +01:00
Adrian Huang fbbcdc0744 intel_pstate: skip the driver if ACPI has power mgmt option
Do not load the Intel pstate driver if the platform firmware
(ACPI BIOS) supports the power management alternatives.
The ACPI BIOS indicates that the OS control mode can be used
if the _PSS (Performance Supported States) is defined in ACPI
table. For the OS control mode, the Intel pstate driver will be
loaded.

HP BIOS has several power management modes (firmware, OS-control and
so on). For the OS control mode in HP BIOS, the Intel p-state driver
will be loaded. When the customer chooses the firmware power
management in HP BIOS, the Intel p-state driver will be ignored.

I put hw_vendor_info vendor_info in case other vendors (Dell, Lenovo...)
have their firmware power management. Vendors should make sure their
firmware power management works properly, and they can go for adding
their vendor info to the variable.

I have verified the patch on HP ProLiant servers.  The patch worked
correctly.

Signed-off-by: Adrian Huang <adrianhuang0701@gmail.com>
[rjw: Fixed up !CONFIG_ACPI build]
[Linda Knippers: As Adrian has recently left HP, I retested the
updated patch on an HP ProLiant server and verified that it is
behaving correctly.  When the BIOS is configured for OS control for
power management, the intel_pstate driver loads as expected.  When
the BIOS is configured to provide the power management, the
intel_pstate driver does not load and we get the pcc_cpufreq driver
instead.]
Signed-off-by: Linda Knippers <linda.knippers@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-11-07 02:05:48 +01:00
Dirk Brandewie e0a261a207 cpufreq/intel_pstate: Add static declarations to internal functions
Fixes warnings reported by kbuild test robot

sparse warnings: (new ones prefixed by >>)

drivers/cpufreq/intel_pstate.c:729:6: sparse: symbol 'copy_pid_params' was not declared. Should it be static?
drivers/cpufreq/intel_pstate.c:739:6: sparse: symbol 'copy_cpu_funcs' was not declared. Should it be static?

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-31 00:11:08 +01:00
Rafael J. Wysocki 93658cb859 Merge branch 'pm-cpufreq'
* pm-cpufreq: (167 commits)
  cpufreq: create per policy rwsem instead of per CPU cpu_policy_rwsem
  intel_pstate: Add Baytrail support
  intel_pstate: Refactor driver to support CPUs with different MSR layouts
  cpufreq: Implement light weight ->target_index() routine
  PM / OPP: rename header to linux/pm_opp.h
  PM / OPP: rename data structures to dev_pm equivalents
  PM / OPP: rename functions to dev_pm_opp*
  cpufreq / governor: Remove fossil comment
  cpufreq: exynos4210: Use the common clock framework to set APLL clock rate
  cpufreq: exynos4x12: Use the common clock framework to set APLL clock rate
  cpufreq: Detect spurious invocations of update_policy_cpu()
  cpufreq: pmac64: enable cpufreq on iMac G5 (iSight) model
  cpufreq: pmac64: provide cpufreq transition latency for older G5 models
  cpufreq: pmac64: speed up frequency switch
  cpufreq: highbank-cpufreq: Enable Midway/ECX-2000
  exynos-cpufreq: fix false return check from "regulator_set_voltage"
  speedstep-centrino: Remove unnecessary braces
  acpi-cpufreq: Add comment under ACPI_ADR_SPACE_SYSTEM_IO case
  cpufreq: arm-big-little: use clk_get instead of clk_get_sys
  cpufreq: exynos: Show a list of available frequencies
  ...

Conflicts:
	drivers/devfreq/exynos/exynos5_bus.c
2013-10-28 01:29:34 +01:00
Dirk Brandewie 19e77c28db intel_pstate: Add Baytrail support
Add support for the Baytrail processor.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-25 23:46:10 +02:00
Dirk Brandewie 016c815084 intel_pstate: Refactor driver to support CPUs with different MSR layouts
Non-core processors have a different MSR layout to commumicate P state
information. Refactor the driver to use CPU dependent accessors to
P state information.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-25 23:46:10 +02:00
Rafael J. Wysocki 6ddee424fe Merge back earlier 'pm-cpufreq' material.
Conflicts:
	drivers/cpufreq/omap-cpufreq.c
2013-10-25 22:36:40 +02:00
Dirk Brandewie 7244cb62d9 intel_pstate: Correct calculation of min pstate value
The minimum pstate is supposed to be a percentage of the maximum P
state available.  Calculate min using max pstate and not the
current max which may have been limited by the user

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-22 01:16:39 +02:00
Brennan Shacklett d253d2a526 intel_pstate: Improve accuracy by not truncating until final result
This patch addresses Bug 60727
(https://bugzilla.kernel.org/show_bug.cgi?id=60727)
which was due to the truncation of intermediate values in the
calculations, which causes the code to consistently underestimate the
current cpu frequency, specifically 100% cpu utilization was truncated
down to the setpoint of 97%. This patch fixes the problem by keeping
the results of all intermediate calculations as fixed point numbers
rather scaling them back and forth between integers and fixed point.

References: https://bugzilla.kernel.org/show_bug.cgi?id=60727
Signed-off-by: Brennan Shacklett <bpshacklett@gmail.com>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-22 01:15:38 +02:00
Rafael J. Wysocki 09c87e2f79 intel_pstate: Fix type mismatch warning
The expression in line 398 of intel_pstate.c causes the following
warning to be emitted:

drivers/cpufreq/intel_pstate.c:398:3: warning: left shift count >= width of type

which happens because unsigned long is 32-bit on some architectures.

Fix that by using a helper u64 variable and simplify the code
slightly.

Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-16 22:59:33 +02:00
Dirk Brandewie 52e0a509e5 cpufreq / intel_pstate: Fix max_perf_pct on resume
If the system is suspended while max_perf_pct is less than 100 percent
or no_turbo set policy->{min,max} will be set incorrectly with scaled
values which turn the scaled values into hard limits.

References: https://bugzilla.kernel.org/show_bug.cgi?id=61241
Reported-by: Patrick Bartels <petzicus@googlemail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Cc: 3.9+ <stable@vger.kernel.org> # 3.9+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-16 01:41:46 +02:00
Viresh Kumar be49e3465f cpufreq: add new routine cpufreq_verify_within_cpu_limits()
Most of the users of cpufreq_verify_within_limits() calls it for
limiting with min/max from policy->cpuinfo. We can make that code
simple by introducing another routine which will do this for them
automatically.

This patch adds another routine cpufreq_verify_within_cpu_limits()
and updates others to use it.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-16 00:50:23 +02:00
Srinivas Pandruvada 1ccf7a1cda intel_pstate: fix no_turbo
When sysfs for no_turbo is set, then also some p states in turbo regions
are observed. This patch will set IDA Engage bit when no_turbo is set to
explicitly disengage turbo.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-10-01 22:51:11 +02:00
Nell Hardcastle 6cdcdb7937 intel_pstate: Add Haswell CPU models
Enable the intel_pstate driver for Haswell CPUs. One missing Ivy Bridge
model (0x3E) is also included. Models referenced from
tools/power/x86/turbostat/turbostat.c:has_nehalem_turbo_ratio_limit

Signed-off-by: Nell Hardcastle <nell@spicious.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-09-10 23:10:39 +02:00
Viresh Kumar adc97d6a73 cpufreq: Drop the owner field from struct cpufreq_driver
We don't need to set .owner = THIS_MODULE any more in cpufreq drivers
as this field isn't used any more by the cpufreq core.

This patch removes it and updates all dependent drivers accordingly.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-08-10 03:24:47 +02:00
Dirk Brandewie 2134ed4d61 cpufreq / intel_pstate: Change to scale off of max P-state
Change to using max P-state instead of max turbo P-state.  This
change resolves two issues.

On a quiet system intel_pstate can fail to respond to a load change.

On CPU SKUs that have a limited number of P-states and no turbo range
intel_pstate fails to select the highest available P-state.

This change is suitable for stable v3.9+

References: https://bugzilla.kernel.org/show_bug.cgi?id=59481
Reported-and-tested-by: Arjan van de Ven <arjan@linux.intel.com>
Reported-and-tested-by: dsmythies@telus.net
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-07-23 04:18:28 +02:00
Paul Gortmaker 2760984f65 cpufreq: delete __cpuinit usage from all cpufreq files
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the drivers/cpufreq uses of the __cpuinit macros
from all C files.

[1] https://lkml.org/lkml/2013/5/20/589

[v2: leave 2nd lines of args misaligned as requested by Viresh]
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: cpufreq@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2013-07-14 19:36:57 -04:00
Dirk Brandewie c96d53d600 cpufreq / intel_pstate: Add additional supported CPU ID
Add CPU ID for Ivybrigde processor.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-22 00:28:44 +02:00
Wei Yongjun b57ffac5e5 cpufreq / intel_pstate: use vzalloc() instead of vmalloc()/memset(0)
Use vzalloc() instead of vmalloc() and memset(0).

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-14 01:39:28 +02:00
Dirk Brandewie 35363e943f cpufreq / intel_pstate: remove #ifdef MODULE compile fence
The driver can no longer be built as a module remove the compile fence
around cpufreq tracing call.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:04:17 +02:00
Dirk Brandewie a73108d578 cpufreq / intel_pstate: Remove idle mode PID
Remove dead code from the driver.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:04:17 +02:00
Dirk Brandewie ca182aee38 cpufreq / intel_pstate: fix ffmpeg regression
The ffmpeg benchmark in the phoronix test suite has threads on
multiple cores that rely on the progress on of threads on other cores
and ping pong back and forth fast enough to make the core appear less
busy than it "should" be.  If the core has been at minimum p-state for
a while bump the pstate up to kick the core to see if it is in this
ping pong state.  If the core is truly idle the p-state will be
reduced at the next sample time.  If the core makes more progress it
will send more work to the thread bringing both threads out of the
ping pong scenario and the p-state will be selected normally.

This fixes a performance regression of approximately 30%

Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:04:16 +02:00
Dirk Brandewie d8f469e9cf cpufreq / intel_pstate: use lowest requested max performance
There are two ways that the maximum p-state can be clamped, via a
policy change and via the sysfs file.

The acpi-thermal driver adjusts the p-state policy in response to
thermal events.  These changes override the users settings at the
moment.

Use the lowest of the two requested values this ensures that we will
not exceed the requested pstate from either mechanism.

Reported-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:04:16 +02:00
Dirk Brandewie 1abc4b20b8 cpufreq / intel_pstate: remove idle time and duration from sample and calculations
Idle time is taken into account in the APERF/MPERF ratio calculation
there is no reason for the driver to track it seperately.  This
reduces the work in the driver and makes the code more readable.

Removal of the tracking of sample duration removes the possibility of
the divide by zero exception when the duration is sub 1us

References: https://bugzilla.kernel.org/show_bug.cgi?id=56691
Reported-by: Mike Lothian <mike@fireburn.co.uk>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-05-12 14:04:16 +02:00
Rafael J. Wysocki 885f925eef Merge branch 'pm-cpufreq'
* pm-cpufreq: (57 commits)
  cpufreq: MAINTAINERS: Add co-maintainer
  cpufreq: pxa2xx: initialize variables
  ARM: S5pv210: compiling issue, ARM_S5PV210_CPUFREQ needs CONFIG_CPU_FREQ_TABLE=y
  cpufreq: cpu0: Put cpu parent node after using it
  cpufreq: ARM big LITTLE: Adapt to latest cpufreq updates
  cpufreq: ARM big LITTLE: put DT nodes after using them
  cpufreq: Don't call __cpufreq_governor() for drivers without target()
  cpufreq: exynos5440: Protect OPP search calls with RCU lock
  cpufreq: dbx500: Round to closest available freq
  cpufreq: Call __cpufreq_governor() with correct policy->cpus mask
  cpufreq / intel_pstate: Optimize intel_pstate_set_policy
  cpufreq: OMAP: instantiate omap-cpufreq as a platform_driver
  arm: exynos: Enable OPP library support for exynos5440
  cpufreq: exynos: Remove error return even if no soc is found
  cpufreq: exynos: Add cpufreq driver for exynos5440
  cpufreq: AMD "frequency sensitivity feedback" powersave bias for ondemand governor
  cpufreq: ondemand: allow custom powersave_bias_target handler to be registered
  cpufreq: convert cpufreq_driver to using RCU
  cpufreq: powerpc/platforms/cell: move cpufreq driver to drivers/cpufreq
  cpufreq: sparc: move cpufreq driver to drivers/cpufreq
  ...

Conflicts:
	MAINTAINERS (with commit a8e39c3 from pm-cpuidle)
	drivers/cpufreq/cpufreq_governor.h (with commit beb0ff3)
2013-04-28 02:10:46 +02:00
Srinivas Pandruvada d1b6848590 cpufreq / intel_pstate: Optimize intel_pstate_set_policy
This function is called quite often from other subsystems.
Removed unused call to intel_pstate_get_min_max().
Also when "policy->policy == CPUFREQ_POLICY_PERFORMANCE", then
no need to do calculations as the limits will be forced anyway.
Also corrected filename in the header.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-04-10 13:42:45 +02:00
Dirk Brandewie ec376a2ab9 cpufreq / intel_pstate: Set timer timeout correctly
The current calculation of the delay time is wrong and a cut and
paste error from a previous experimental driver.  This can result in
the timeout being set to jiffies + 1 which setup the driver to race
with itself if the APIC timer interrupt happens at just the right
time.

References: https://bugzilla.redhat.com/show_bug.cgi?id=920289
Reported-by: Adam Williamson <awilliam@redhat.com>
Reported-and-tested-by: Parag Warudkar <parag.lkml@gmail.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-04-08 22:09:23 +02:00
Konrad Rzeszutek Wilk 05e99c8cf9 intel-pstate: Use #defines instead of hard-coded values.
They are defined in coreboot (MSR_PLATFORM) and the other
one is already defined in msr-index.h.

Let's use those.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-03-25 15:13:07 +01:00
Dirk Brandewie e6f3eb29be cpufreq / intel_pstate: Fix calculation of current frequency
Use the correct pstate value to calculate the effective frequency.

References: https://bugzilla.redhat.com/show_bug.cgi?id=923942
Reported-by: Satish Balay <balay@fastmail.fm>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-03-25 15:12:59 +01:00
Dirk Brandewie b563b4e3f2 cpufreq / intel_pstate: Add function to check that all MSRs are valid
Some VMs seem to try to implement some MSRs but not all the registers
the driver needs.  Check to make sure all the MSR that we need are
available. If any of the required MSRs are not available refuse to
load.

References: https://bugzilla.redhat.com/show_bug.cgi?id=922923
Reported-by: Josh Stone <jistone@redhat.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-03-25 15:12:52 +01:00
Dirk Brandewie d3929b8328 cpufreq / intel_pstate: Do not load on VM that does not report max P state.
It seems some VMs support the P state MSRs but return zeros. Fail
gracefully if we are running in this environment.

References: https://bugzilla.redhat.com/show_bug.cgi?id=916833
Reported-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-03-06 23:40:11 +01:00
Dirk Brandewie 907cc90810 cpufreq / intel_pstate: Fix intel_pstate_init() error path
If cpufreq_register_driver() fails just free memory that has been
allocated and return. intel_pstate_exit() function is removed since we
are built-in only now there is no reason for a module exit procedure.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-03-06 23:34:58 +01:00
Dirk Brandewie 6be2649861 cpufreq / intel_pstate: Add kernel command line option disable intel_pstate.
When intel_pstate is configured into the kernel it will become the
preferred scaling driver for processors that it supports.  Allow the
user to override this by adding:
   intel_pstate=disable
on the kernel command line.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-15 22:55:10 +01:00
Dirk Brandewie 191e5edf96 cpufreq / intel_pstate: Fix 32 bit build
Fixes 32 bit build.

on i386:
drivers/built-in.o: In function `intel_pstate_timer_func':
intel_pstate.c:(.text+0x4ce97e): undefined reference to `__udivdi3'
drivers/built-in.o: In function `intel_pstate_cpu_init':
intel_pstate.c:(.cpuinit.text+0x974): undefined reference to `__udivdi3'

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-11 20:33:34 +01:00
Dirk Brandewie 93f0822dff cpufreq/x86: Add P-state driver for sandy bridge.
Add a P-state driver for the Intel Sandy bridge processor. In cpufreq
terminology this driver implements a  scaling driver with an internal
governor.

When built into the the kernel this driver will be the preferred
scaling driver for Sandy bridge processors.

In addition to the interfaces provided by the cpufreq subsystem for
controlling scaling drivers. The user may control the behavior of the
driver via three sysfs files located in
"/sys/devices/system/cpu/intel_pstate".

  max_perf_pct: limits the maximum P state that will be requested by
  the driver stated as a percentage of the avail performance.

  min_perf_pct: limits the minimum P state that will be  requested by
  the driver stated as a percentage of the avail performance.

  no_turbo: limits the driver to selecting P states below the turbo
  frequency range.

Signed-off-by: Dirk Brandewie <dirk.j.brandewie@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2013-02-09 12:56:04 +01:00