Merge back earlier 'pm-cpufreq' material.

2 files changed, 64 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 468e4d4..d5a0d33 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -200,3 +200,27 @@ Description:	address and size of the percpu note.
 		note of cpu#.
 
 		crash_notes_size: size of the note of cpu#.
+
+
+What:		/sys/devices/system/cpu/intel_pstate/max_perf_pct
+		/sys/devices/system/cpu/intel_pstate/min_perf_pct
+		/sys/devices/system/cpu/intel_pstate/no_turbo
+Date:		February 2013
+Contact:	linux-pm@vger.kernel.org
+Description:	Parameters for the Intel P-state driver
+
+		Logic for selecting the current P-state in Intel
+		Sandybridge+ processors. The three knobs control
+		limits for the P-state that will be requested by the
+		driver.
+
+		max_perf_pct: limits the maximum P state that will be requested by
+		the driver stated as a percentage of the available performance.
+
+		min_perf_pct: limits the minimum P state that will be requested by
+		the driver stated as a percentage of the available performance.
+
+		no_turbo: limits the driver to selecting P states below the turbo
+		frequency range.
+
+		More details can be found in Documentation/cpu-freq/intel-pstate.txt
diff --git a/Documentation/cpu-freq/intel-pstate.txt b/Documentation/cpu-freq/intel-pstate.txt
new file mode 100644
index 0000000..e742d21
--- /dev/null
+++ b/Documentation/cpu-freq/intel-pstate.txt
@@ -0,0 +1,40 @@
+Intel P-state driver
+--------------------
+
+This driver implements a scaling driver with an internal governor for
+Intel Core processors.  The driver follows the same model as the
+Transmeta scaling driver (longrun.c) and implements the setpolicy()
+instead of target().  Scaling drivers that implement setpolicy() are
+assumed to implement internal governors by the cpufreq core. All the
+logic for selecting the current P state is contained within the
+driver; no external governor is used by the cpufreq core.
+
+Intel SandyBridge+ processors are supported.
+
+New sysfs files for controlling P state selection have been added to
+/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 available performance.
+
+      min_perf_pct: limits the minimum P state that will be  requested by
+      the driver stated as a percentage of the available performance.
+
+      no_turbo: limits the driver to selecting P states below the turbo
+      frequency range.
+
+For contemporary Intel processors, the frequency is controlled by the
+processor itself and the P-states exposed to software are related to
+performance levels.  The idea that frequency can be set to a single
+frequency is fiction for Intel Core processors. Even if the scaling
+driver selects a single P state the actual frequency the processor
+will run at is selected by the processor itself.
+
+New debugfs files have also been added to /sys/kernel/debug/pstate_snb/
+
+      deadband
+      d_gain_pct
+      i_gain_pct
+      p_gain_pct
+      sample_rate_ms
+      setpoint