summaryrefslogtreecommitdiffstats
path: root/kernel/Documentation/cpu-freq
diff options
context:
space:
mode:
authorJosé Pekkarinen <jose.pekkarinen@nokia.com>2016-04-11 10:41:07 +0300
committerJosé Pekkarinen <jose.pekkarinen@nokia.com>2016-04-13 08:17:18 +0300
commite09b41010ba33a20a87472ee821fa407a5b8da36 (patch)
treed10dc367189862e7ca5c592f033dc3726e1df4e3 /kernel/Documentation/cpu-freq
parentf93b97fd65072de626c074dbe099a1fff05ce060 (diff)
These changes are the raw update to linux-4.4.6-rt14. Kernel sources
are taken from kernel.org, and rt patch from the rt wiki download page. During the rebasing, the following patch collided: Force tick interrupt and get rid of softirq magic(I70131fb85). Collisions have been removed because its logic was found on the source already. Change-Id: I7f57a4081d9deaa0d9ccfc41a6c8daccdee3b769 Signed-off-by: José Pekkarinen <jose.pekkarinen@nokia.com>
Diffstat (limited to 'kernel/Documentation/cpu-freq')
-rw-r--r--kernel/Documentation/cpu-freq/core.txt7
-rw-r--r--kernel/Documentation/cpu-freq/governors.txt2
-rw-r--r--kernel/Documentation/cpu-freq/intel-pstate.txt21
-rw-r--r--kernel/Documentation/cpu-freq/user-guide.txt2
4 files changed, 14 insertions, 18 deletions
diff --git a/kernel/Documentation/cpu-freq/core.txt b/kernel/Documentation/cpu-freq/core.txt
index 70933eadc..ba78e7c2a 100644
--- a/kernel/Documentation/cpu-freq/core.txt
+++ b/kernel/Documentation/cpu-freq/core.txt
@@ -55,16 +55,13 @@ transition notifiers.
----------------------------
These are notified when a new policy is intended to be set. Each
-CPUFreq policy notifier is called three times for a policy transition:
+CPUFreq policy notifier is called twice for a policy transition:
1.) During CPUFREQ_ADJUST all CPUFreq notifiers may change the limit if
they see a need for this - may it be thermal considerations or
hardware limitations.
-2.) During CPUFREQ_INCOMPATIBLE only changes may be done in order to avoid
- hardware failure.
-
-3.) And during CPUFREQ_NOTIFY all notifiers are informed of the new policy
+2.) And during CPUFREQ_NOTIFY all notifiers are informed of the new policy
- if two hardware drivers failed to agree on a new policy before this
stage, the incompatible hardware shall be shut down, and the user
informed of this.
diff --git a/kernel/Documentation/cpu-freq/governors.txt b/kernel/Documentation/cpu-freq/governors.txt
index 77ec21574..c15aa75f5 100644
--- a/kernel/Documentation/cpu-freq/governors.txt
+++ b/kernel/Documentation/cpu-freq/governors.txt
@@ -36,7 +36,7 @@ Contents:
1. What Is A CPUFreq Governor?
==============================
-Most cpufreq drivers (in fact, all except one, longrun) or even most
+Most cpufreq drivers (except the intel_pstate and longrun) or even most
cpu frequency scaling algorithms only offer the CPU to be set to one
frequency. In order to offer dynamic frequency scaling, the cpufreq
core must be able to tell these drivers of a "target frequency". So
diff --git a/kernel/Documentation/cpu-freq/intel-pstate.txt b/kernel/Documentation/cpu-freq/intel-pstate.txt
index 655750743..be8d4006b 100644
--- a/kernel/Documentation/cpu-freq/intel-pstate.txt
+++ b/kernel/Documentation/cpu-freq/intel-pstate.txt
@@ -3,24 +3,25 @@ Intel P-state driver
This driver provides an interface to control the P state selection for
SandyBridge+ Intel processors. The driver can operate two different
-modes based on the processor model legacy and Hardware P state (HWP)
+modes based on the processor model, legacy mode and Hardware P state (HWP)
mode.
-In legacy mode the 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.
+In legacy mode, the Intel P-state implements two internal governors,
+performance and powersave, that differ from the general cpufreq governors of
+the same name (the general cpufreq governors implement target(), whereas the
+internal Intel P-state governors implement setpolicy()). The internal
+performance governor sets the max_perf_pct and min_perf_pct to 100; that is,
+the governor selects the highest available P state to maximize the performance
+of the core. The internal powersave governor selects the appropriate P state
+based on the current load on the CPU.
In HWP mode P state selection is implemented in the processor
itself. The driver provides the interfaces between the cpufreq core and
the processor to control P state selection based on user preferences
and reporting frequency to the cpufreq core. In this mode the
-internal governor code is disabled.
+internal Intel P-state governor code is disabled.
-In addtion to the interfaces provided by the cpufreq core for
+In addition to the interfaces provided by the cpufreq core for
controlling frequency the driver provides sysfs files for
controlling P state selection. These files have been added to
/sys/devices/system/cpu/intel_pstate/
diff --git a/kernel/Documentation/cpu-freq/user-guide.txt b/kernel/Documentation/cpu-freq/user-guide.txt
index ff2f28332..109e97bba 100644
--- a/kernel/Documentation/cpu-freq/user-guide.txt
+++ b/kernel/Documentation/cpu-freq/user-guide.txt
@@ -196,8 +196,6 @@ affected_cpus : List of Online CPUs that require software
related_cpus : List of Online + Offline CPUs that need software
coordination of frequency.
-scaling_driver : Hardware driver for cpufreq.
-
scaling_cur_freq : Current frequency of the CPU as determined by
the governor and cpufreq core, in KHz. This is
the frequency the kernel thinks the CPU runs