Merge tag 'pm-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management updates from Rafael Wysocki:
 "The majority of changes go into the Operating Performance Points (OPP)
  framework and cpufreq this time, followed by devfreq and some
  scattered updates all over.

  The OPP changes are mostly related to switching over from RCU-based
  synchronization, that turned out to be overly complicated and
  problematic, to reference counting using krefs.

  In the cpufreq land there are core cleanups, documentation updates, a
  new driver for Broadcom BMIPS SoCs, a new cpufreq-dt sub-driver for TI
  SoCs that require special handling, ARM64 SoCs support for the qoriq
  driver, intel_pstate updates, powernv driver update and assorted
  fixes.

  The devfreq changes are mostly fixes related to the sysfs interface
  and some Exynos drivers updates.

  Apart from that, the cpuidle menu governor will support per-CPU PM QoS
  constraints for the wakeup latency now, some bugs in the wakeup IRQs
  framework are fixed, the generic power domains framework should handle
  asynchronous invocations of *noirq suspend/resume callbacks from now
  on, the analyze_suspend.py script is updated and there is a new tool
  for intel_pstate diagnostics.

  Specifics:

   - Operating Performance Points (OPP) framework fixes, cleanups and
     switch over from RCU-based synchronization to reference counting
     using krefs (Viresh Kumar, Wei Yongjun, Dave Gerlach)

   - cpufreq core cleanups and documentation updates (Viresh Kumar,
     Rafael Wysocki)

   - New cpufreq driver for Broadcom BMIPS SoCs (Markus Mayer)

   - New cpufreq-dt sub-driver for TI SoCs requiring special handling,
     like in the AM335x, AM437x, DRA7x, and AM57x families, along with
     new DT bindings for it (Dave Gerlach, Paul Gortmaker)

   - ARM64 SoCs support for the qoriq cpufreq driver (Tang Yuantian)

   - intel_pstate driver updates including a new sysfs knob to control
     the driver's operation mode and fixes related to the no_turbo sysfs
     knob and the hardware-managed P-states feature support (Rafael
     Wysocki, Srinivas Pandruvada)

   - New interface to export ultra-turbo frequencies for the powernv
     cpufreq driver (Shilpasri Bhat)

   - Assorted fixes for cpufreq drivers (Arnd Bergmann, Dan Carpenter,
     Wei Yongjun)

   - devfreq core fixes, mostly related to the sysfs interface exported
     by it (Chanwoo Choi, Chris Diamand)

   - Updates of the exynos-bus and exynos-ppmu devfreq drivers (Chanwoo
     Choi)

   - Device PM QoS extension to support CPUs and support for per-CPU
     wakeup (device resume) latency constraints in the cpuidle menu
     governor (Alex Shi)

   - Wakeup IRQs framework fixes (Grygorii Strashko)

   - Generic power domains framework update including a fix to make it
     handle asynchronous invocations of *noirq suspend/resume callbacks
     correctly (Ulf Hansson, Geert Uytterhoeven)

   - Assorted fixes and cleanups in the core suspend/hibernate code, PM
     QoS framework and x86 ACPI idle support code (Corentin Labbe, Geert
     Uytterhoeven, Geliang Tang, John Keeping, Nick Desaulniers)

   - Update of the analyze_suspend.py script is updated to version 4.5
     offering multiple improvements (Todd Brandt)

   - New tool for intel_pstate diagnostics using the pstate_sample
     tracepoint (Doug Smythies)"

* tag 'pm-4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (85 commits)
  MAINTAINERS: cpufreq: add bmips-cpufreq.c
  PM / QoS: Fix memory leak on resume_latency.notifiers
  PM / Documentation: Spelling s/wrtie/write/
  PM / sleep: Fix test_suspend after sleep state rework
  cpufreq: CPPC: add ACPI_PROCESSOR dependency
  cpufreq: make ti-cpufreq explicitly non-modular
  cpufreq: Do not clear real_cpus mask on policy init
  tools/power/x86: Debug utility for intel_pstate driver
  AnalyzeSuspend: fix drag and zoom bug in javascript
  PM / wakeirq: report a wakeup_event on dedicated wekup irq
  PM / wakeirq: Fix spurious wake-up events for dedicated wakeirqs
  PM / wakeirq: Enable dedicated wakeirq for suspend
  cpufreq: dt: Don't use generic platdev driver for ti-cpufreq platforms
  cpufreq: ti: Add cpufreq driver to determine available OPPs at runtime
  Documentation: dt: add bindings for ti-cpufreq
  PM / OPP: Expose _of_get_opp_desc_node as dev_pm_opp API
  cpufreq: qoriq: Don't look at clock implementation details
  cpufreq: qoriq: add ARM64 SoCs support
  PM / Domains: Provide dummy governors if CONFIG_PM_GENERIC_DOMAINS=n
  cpufreq: brcmstb-avs-cpufreq: remove unnecessary platform_set_drvdata()
  ...

1 files changed, 177 insertions, 145 deletions

diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt
index c15aa75f5227..61b3184b6c24 100644
--- a/Documentation/cpu-freq/governors.txt
+++ b/Documentation/cpu-freq/governors.txt
@@ -10,6 +10,8 @@
 
 		    Dominik Brodowski  <linux@brodo.de>
             some additions and corrections by Nico Golde <nico@ngolde.de>
+		Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+		   Viresh Kumar <viresh.kumar@linaro.org>
 
 
 
@@ -28,32 +30,27 @@ Contents:
 2.3  Userspace
 2.4  Ondemand
 2.5  Conservative
+2.6  Schedutil
 
 3.   The Governor Interface in the CPUfreq Core
 
+4.   References
 
 
 1. What Is A CPUFreq Governor?
 ==============================
 
 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
-these specific drivers will be transformed to offer a "->target/target_index"
-call instead of the existing "->setpolicy" call. For "longrun", all
-stays the same, though.
+cpu frequency scaling algorithms only allow the CPU frequency to be set
+to predefined fixed values.  In order to offer dynamic frequency
+scaling, the cpufreq core must be able to tell these drivers of a
+"target frequency". So these specific drivers will be transformed to
+offer a "->target/target_index/fast_switch()" call instead of the
+"->setpolicy()" call. For set_policy drivers, all stays the same,
+though.
 
 How to decide what frequency within the CPUfreq policy should be used?
-That's done using "cpufreq governors". Two are already in this patch
--- they're the already existing "powersave" and "performance" which
-set the frequency statically to the lowest or highest frequency,
-respectively. At least two more such governors will be ready for
-addition in the near future, but likely many more as there are various
-different theories and models about dynamic frequency scaling
-around. Using such a generic interface as cpufreq offers to scaling
-governors, these can be tested extensively, and the best one can be
-selected for each specific use.
+That's done using "cpufreq governors".
 
 Basically, it's the following flow graph:
 
@@ -71,7 +68,7 @@ CPU can be set to switch independently	 |	   CPU can only be set
 		    /			       the limits of policy->{min,max}
 		   /			            \
 		  /				     \
-	Using the ->setpolicy call,		 Using the ->target/target_index call,
+	Using the ->setpolicy call,		 Using the ->target/target_index/fast_switch call,
 	    the limits and the			  the frequency closest
 	     "policy" is set.			  to target_freq is set.
 						  It is assured that it
@@ -109,114 +106,159 @@ directory.
 2.4 Ondemand
 ------------
 
-The CPUfreq governor "ondemand" sets the CPU depending on the
-current usage. To do this the CPU must have the capability to
-switch the frequency very quickly.  There are a number of sysfs file
-accessible parameters:
-
-sampling_rate: measured in uS (10^-6 seconds), this is how often you
-want the kernel to look at the CPU usage and to make decisions on
-what to do about the frequency.  Typically this is set to values of
-around '10000' or more. It's default value is (cmp. with users-guide.txt):
-transition_latency * 1000
-Be aware that transition latency is in ns and sampling_rate is in us, so you
-get the same sysfs value by default.
-Sampling rate should always get adjusted considering the transition latency
-To set the sampling rate 750 times as high as the transition latency
-in the bash (as said, 1000 is default), do:
-echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) \
-    >ondemand/sampling_rate
-
-sampling_rate_min:
-The sampling rate is limited by the HW transition latency:
-transition_latency * 100
-Or by kernel restrictions:
-If CONFIG_NO_HZ_COMMON is set, the limit is 10ms fixed.
-If CONFIG_NO_HZ_COMMON is not set or nohz=off boot parameter is used, the
-limits depend on the CONFIG_HZ option:
-HZ=1000: min=20000us  (20ms)
-HZ=250:  min=80000us  (80ms)
-HZ=100:  min=200000us (200ms)
-The highest value of kernel and HW latency restrictions is shown and
-used as the minimum sampling rate.
-
-up_threshold: defines what the average CPU usage between the samplings
-of 'sampling_rate' needs to be for the kernel to make a decision on
-whether it should increase the frequency.  For example when it is set
-to its default value of '95' it means that between the checking
-intervals the CPU needs to be on average more than 95% in use to then
-decide that the CPU frequency needs to be increased.  
-
-ignore_nice_load: this parameter takes a value of '0' or '1'. When
-set to '0' (its default), all processes are counted towards the
-'cpu utilisation' value.  When set to '1', the processes that are
-run with a 'nice' value will not count (and thus be ignored) in the
-overall usage calculation.  This is useful if you are running a CPU
-intensive calculation on your laptop that you do not care how long it
-takes to complete as you can 'nice' it and prevent it from taking part
-in the deciding process of whether to increase your CPU frequency.
-
-sampling_down_factor: this parameter controls the rate at which the
-kernel makes a decision on when to decrease the frequency while running
-at top speed. When set to 1 (the default) decisions to reevaluate load
-are made at the same interval regardless of current clock speed. But
-when set to greater than 1 (e.g. 100) it acts as a multiplier for the
-scheduling interval for reevaluating load when the CPU is at its top
-speed due to high load. This improves performance by reducing the overhead
-of load evaluation and helping the CPU stay at its top speed when truly
-busy, rather than shifting back and forth in speed. This tunable has no
-effect on behavior at lower speeds/lower CPU loads.
-
-powersave_bias: this parameter takes a value between 0 to 1000. It
-defines the percentage (times 10) value of the target frequency that
-will be shaved off of the target. For example, when set to 100 -- 10%,
-when ondemand governor would have targeted 1000 MHz, it will target
-1000 MHz - (10% of 1000 MHz) = 900 MHz instead. This is set to 0
-(disabled) by default.
-When AMD frequency sensitivity powersave bias driver --
-drivers/cpufreq/amd_freq_sensitivity.c is loaded, this parameter
-defines the workload frequency sensitivity threshold in which a lower
-frequency is chosen instead of ondemand governor's original target.
-The frequency sensitivity is a hardware reported (on AMD Family 16h
-Processors and above) value between 0 to 100% that tells software how
-the performance of the workload running on a CPU will change when
-frequency changes. A workload with sensitivity of 0% (memory/IO-bound)
-will not perform any better on higher core frequency, whereas a
-workload with sensitivity of 100% (CPU-bound) will perform better
-higher the frequency. When the driver is loaded, this is set to 400
-by default -- for CPUs running workloads with sensitivity value below
-40%, a lower frequency is chosen. Unloading the driver or writing 0
-will disable this feature.
+The CPUfreq governor "ondemand" sets the CPU frequency depending on the
+current system load. Load estimation is triggered by the scheduler
+through the update_util_data->func hook; when triggered, cpufreq checks
+the CPU-usage statistics over the last period and the governor sets the
+CPU accordingly.  The CPU must have the capability to switch the
+frequency very quickly.
+
+Sysfs files:
+
+* sampling_rate:
+
+  Measured in uS (10^-6 seconds), this is how often you want the kernel
+  to look at the CPU usage and to make decisions on what to do about the
+  frequency.  Typically this is set to values of around '10000' or more.
+  It's default value is (cmp. with users-guide.txt): transition_latency
+  * 1000.  Be aware that transition latency is in ns and sampling_rate
+  is in us, so you get the same sysfs value by default.  Sampling rate
+  should always get adjusted considering the transition latency to set
+  the sampling rate 750 times as high as the transition latency in the
+  bash (as said, 1000 is default), do:
+
+  $ echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) > ondemand/sampling_rate
+
+* sampling_rate_min:
+
+  The sampling rate is limited by the HW transition latency:
+  transition_latency * 100
+
+  Or by kernel restrictions:
+  - If CONFIG_NO_HZ_COMMON is set, the limit is 10ms fixed.
+  - If CONFIG_NO_HZ_COMMON is not set or nohz=off boot parameter is
+    used, the limits depend on the CONFIG_HZ option:
+    HZ=1000: min=20000us  (20ms)
+    HZ=250:  min=80000us  (80ms)
+    HZ=100:  min=200000us (200ms)
+
+  The highest value of kernel and HW latency restrictions is shown and
+  used as the minimum sampling rate.
+
+* up_threshold:
+
+  This defines what the average CPU usage between the samplings of
+  'sampling_rate' needs to be for the kernel to make a decision on
+  whether it should increase the frequency.  For example when it is set
+  to its default value of '95' it means that between the checking
+  intervals the CPU needs to be on average more than 95% in use to then
+  decide that the CPU frequency needs to be increased.
+
+* ignore_nice_load:
+
+  This parameter takes a value of '0' or '1'. When set to '0' (its
+  default), all processes are counted towards the 'cpu utilisation'
+  value.  When set to '1', the processes that are run with a 'nice'
+  value will not count (and thus be ignored) in the overall usage
+  calculation.  This is useful if you are running a CPU intensive
+  calculation on your laptop that you do not care how long it takes to
+  complete as you can 'nice' it and prevent it from taking part in the
+  deciding process of whether to increase your CPU frequency.
+
+* sampling_down_factor:
+
+  This parameter controls the rate at which the kernel makes a decision
+  on when to decrease the frequency while running at top speed. When set
+  to 1 (the default) decisions to reevaluate load are made at the same
+  interval regardless of current clock speed. But when set to greater
+  than 1 (e.g. 100) it acts as a multiplier for the scheduling interval
+  for reevaluating load when the CPU is at its top speed due to high
+  load. This improves performance by reducing the overhead of load
+  evaluation and helping the CPU stay at its top speed when truly busy,
+  rather than shifting back and forth in speed. This tunable has no
+  effect on behavior at lower speeds/lower CPU loads.
+
+* powersave_bias:
+
+  This parameter takes a value between 0 to 1000. It defines the
+  percentage (times 10) value of the target frequency that will be
+  shaved off of the target. For example, when set to 100 -- 10%, when
+  ondemand governor would have targeted 1000 MHz, it will target
+  1000 MHz - (10% of 1000 MHz) = 900 MHz instead. This is set to 0
+  (disabled) by default.
+
+  When AMD frequency sensitivity powersave bias driver --
+  drivers/cpufreq/amd_freq_sensitivity.c is loaded, this parameter
+  defines the workload frequency sensitivity threshold in which a lower
+  frequency is chosen instead of ondemand governor's original target.
+  The frequency sensitivity is a hardware reported (on AMD Family 16h
+  Processors and above) value between 0 to 100% that tells software how
+  the performance of the workload running on a CPU will change when
+  frequency changes. A workload with sensitivity of 0% (memory/IO-bound)
+  will not perform any better on higher core frequency, whereas a
+  workload with sensitivity of 100% (CPU-bound) will perform better
+  higher the frequency. When the driver is loaded, this is set to 400 by
+  default -- for CPUs running workloads with sensitivity value below
+  40%, a lower frequency is chosen. Unloading the driver or writing 0
+  will disable this feature.
 
 
 2.5 Conservative
 ----------------
 
 The CPUfreq governor "conservative", much like the "ondemand"
-governor, sets the CPU depending on the current usage.  It differs in
-behaviour in that it gracefully increases and decreases the CPU speed
-rather than jumping to max speed the moment there is any load on the
-CPU.  This behaviour more suitable in a battery powered environment.
-The governor is tweaked in the same manner as the "ondemand" governor
-through sysfs with the addition of:
-
-freq_step: this describes what percentage steps the cpu freq should be
-increased and decreased smoothly by.  By default the cpu frequency will
-increase in 5% chunks of your maximum cpu frequency.  You can change this
-value to anywhere between 0 and 100 where '0' will effectively lock your
-CPU at a speed regardless of its load whilst '100' will, in theory, make
-it behave identically to the "ondemand" governor.
-
-down_threshold: same as the 'up_threshold' found for the "ondemand"
-governor but for the opposite direction.  For example when set to its
-default value of '20' it means that if the CPU usage needs to be below
-20% between samples to have the frequency decreased.
-
-sampling_down_factor: similar functionality as in "ondemand" governor.
-But in "conservative", it controls the rate at which the kernel makes
-a decision on when to decrease the frequency while running in any
-speed. Load for frequency increase is still evaluated every
-sampling rate.
+governor, sets the CPU frequency depending on the current usage.  It
+differs in behaviour in that it gracefully increases and decreases the
+CPU speed rather than jumping to max speed the moment there is any load
+on the CPU. This behaviour is more suitable in a battery powered
+environment.  The governor is tweaked in the same manner as the
+"ondemand" governor through sysfs with the addition of:
+
+* freq_step:
+
+  This describes what percentage steps the cpu freq should be increased
+  and decreased smoothly by.  By default the cpu frequency will increase
+  in 5% chunks of your maximum cpu frequency.  You can change this value
+  to anywhere between 0 and 100 where '0' will effectively lock your CPU
+  at a speed regardless of its load whilst '100' will, in theory, make
+  it behave identically to the "ondemand" governor.
+
+* down_threshold:
+
+  Same as the 'up_threshold' found for the "ondemand" governor but for
+  the opposite direction.  For example when set to its default value of
+  '20' it means that if the CPU usage needs to be below 20% between
+  samples to have the frequency decreased.
+
+* sampling_down_factor:
+
+  Similar functionality as in "ondemand" governor.  But in
+  "conservative", it controls the rate at which the kernel makes a
+  decision on when to decrease the frequency while running in any speed.
+  Load for frequency increase is still evaluated every sampling rate.
+
+
+2.6 Schedutil
+-------------
+
+The "schedutil" governor aims at better integration with the Linux
+kernel scheduler.  Load estimation is achieved through the scheduler's
+Per-Entity Load Tracking (PELT) mechanism, which also provides
+information about the recent load [1].  This governor currently does
+load based DVFS only for tasks managed by CFS. RT and DL scheduler tasks
+are always run at the highest frequency.  Unlike all the other
+governors, the code is located under the kernel/sched/ directory.
+
+Sysfs files:
+
+* rate_limit_us:
+
+  This contains a value in microseconds. The governor waits for
+  rate_limit_us time before reevaluating the load again, after it has
+  evaluated the load once.
+
+For an in-depth comparison with the other governors refer to [2].
+
 
 3. The Governor Interface in the CPUfreq Core
 =============================================
@@ -225,26 +267,10 @@ A new governor must register itself with the CPUfreq core using
 "cpufreq_register_governor". The struct cpufreq_governor, which has to
 be passed to that function, must contain the following values:
 
-governor->name -	    A unique name for this governor
-governor->governor -	    The governor callback function
-governor->owner	-	    .THIS_MODULE for the governor module (if 
-			    appropriate)
-
-The governor->governor callback is called with the current (or to-be-set)
-cpufreq_policy struct for that CPU, and an unsigned int event. The
-following events are currently defined:
-
-CPUFREQ_GOV_START:   This governor shall start its duty for the CPU
-		     policy->cpu
-CPUFREQ_GOV_STOP:    This governor shall end its duty for the CPU
-		     policy->cpu
-CPUFREQ_GOV_LIMITS:  The limits for CPU policy->cpu have changed to
-		     policy->min and policy->max.
-
-If you need other "events" externally of your driver, _only_ use the
-cpufreq_governor_l(unsigned int cpu, unsigned int event) call to the
-CPUfreq core to ensure proper locking.
+governor->name - A unique name for this governor.
+governor->owner - .THIS_MODULE for the governor module (if appropriate).
 
+plus a set of hooks to the functions implementing the governor's logic.
 
 The CPUfreq governor may call the CPU processor driver using one of
 these two functions:
@@ -258,12 +284,18 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
                                    unsigned int relation);
 
 target_freq must be within policy->min and policy->max, of course.
-What's the difference between these two functions? When your governor
-still is in a direct code path of a call to governor->governor, the
-per-CPU cpufreq lock is still held in the cpufreq core, and there's
-no need to lock it again (in fact, this would cause a deadlock). So
-use __cpufreq_driver_target only in these cases. In all other cases 
-(for example, when there's a "daemonized" function that wakes up 
-every second), use cpufreq_driver_target to lock the cpufreq per-CPU
-lock before the command is passed to the cpufreq processor driver.
+What's the difference between these two functions? When your governor is
+in a direct code path of a call to governor callbacks, like
+governor->start(), the policy->rwsem is still held in the cpufreq core,
+and there's no need to lock it again (in fact, this would cause a
+deadlock). So use __cpufreq_driver_target only in these cases. In all
+other cases (for example, when there's a "daemonized" function that
+wakes up every second), use cpufreq_driver_target to take policy->rwsem
+before the command is passed to the cpufreq driver.
+
+4. References
+=============
+
+[1] Per-entity load tracking: https://lwn.net/Articles/531853/
+[2] Improvements in CPU frequency management: https://lwn.net/Articles/682391/