linux.git/Documentation/thermal, branch v4.3

thermal: power_allocator: relax the requirement of two passive trip points

2015-09-14T14:41:45+00:00

The power allocator governor currently requires that the thermal zone
has at least two passive trip points.  If there aren't, the governor
refuses to bind to the thermal zone.

This commit relaxes that requirement.  Now the governor will bind to all
thermal zones regardless of how many trip points they have.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Reviewed-by: Daniel Kurtz 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin

thermal: add available policies sysfs attribute

2015-08-03T15:15:50+00:00

The Linux thermal framework support to change thermal governor
policy in userspace, but it can't show what available policies
supported.

This patch adds available_policies attribute to the thermal
framework, it can list the thermal governors which can be
used for a particular zone. This attribute is read only.

Signed-off-by: Wei Ni 
Reviewed-by: Javi Merino 
Signed-off-by: Zhang Rui

thermal: support slope and offset coefficients

2015-05-12T02:46:52+00:00

It is common to have a linear extrapolation from
the current sensor readings and the actual temperature
value. This is specially the case when the sensor
is in use to extrapolate hotspots.

This patch adds slope and offset constants for
single sensor linear extrapolation equation. Because
the same sensor can be use in different locations,
from board to board, these constants are added
as part of thermal_zone_params.

The constants are available through sysfs.

It is up to the device driver to determine
the usage of these values.

Signed-off-by: Eduardo Valentin

thermal: export thermal_zone_parameters to sysfs

2015-05-05T04:27:54+00:00

It's useful for tuning to be able to edit thermal_zone_parameters from
userspace.  Export them to the thermal_zone sysfs so that they can be
easily changed.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin

thermal: introduce the Power Allocator governor

2015-05-05T04:27:52+00:00

The power allocator governor is a thermal governor that controls system
and device power allocation to control temperature.  Conceptually, the
implementation divides the sustainable power of a thermal zone among
all the heat sources in that zone.

This governor relies on "power actors", entities that represent heat
sources.  They can report current and maximum power consumption and
can set a given maximum power consumption, usually via a cooling
device.

The governor uses a Proportional Integral Derivative (PID) controller
driven by the temperature of the thermal zone.  The output of the
controller is a power budget that is then allocated to each power
actor that can have bearing on the temperature we are trying to
control.  It decides how much power to give each cooling device based
on the performance they are requesting.  The PID controller ensures
that the total power budget does not exceed the control temperature.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Signed-off-by: Punit Agrawal 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin

thermal: cpu_cooling: implement the power cooling device API

2015-05-05T04:27:52+00:00

Add a basic power model to the cpu cooling device to implement the
power cooling device API.  The power model uses the current frequency,
current load and OPPs for the power calculations.  The cpus must have
registered their OPPs using the OPP library.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Signed-off-by: Kapileshwar Singh 
Signed-off-by: Punit Agrawal 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin

thermal: fair_share: generalize the weight concept

2015-05-05T04:27:51+00:00

The fair share governor has the concept of weights, which is the
influence of each cooling device in a thermal zone.  The current
implementation forces the weights of all cooling devices in a thermal
zone to add up to a 100.  This complicates setups, as you need to know
in advance how many cooling devices you are going to have.  If you bind a
new cooling device, you have to modify all the other cooling devices
weights, which is error prone.  Furthermore, you can't specify a
"default" weight for platforms since that default value depends on the
number of cooling devices in the platform.

This patch generalizes the concept of weight by allowing any number to
be a "weight".  Weights are now relative to each other.  Platforms that
don't specify weights get the same default value for all their cooling
devices, so all their cdevs are considered to be equally influential.

It's important to note that previous users of the weights don't need to
alter the code: percentages continue to work as they used to.  This
patch just removes the constraint of all the weights in a thermal zone
having to add up to a 100.  If they do, you get the same behavior as
before.  If they don't, fair share now works for that platform.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Cc: Durgadoss R 
Acked-by: Durgadoss R 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin

thermal: export weight to sysfs

2015-05-05T04:27:51+00:00

It's useful to have access to the weights for the cooling devices for
thermal zones and change them if needed.  Export them to sysfs.

Cc: Zhang Rui 
Cc: Eduardo Valentin 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin

thermal: of: fix cooling device weights in device tree

2015-05-05T04:27:50+00:00

Currently you can specify the weight of the cooling device in the device
tree but that information is not populated to the
thermal_bind_params where the fair share governor expects it to
be.  The of thermal zone device doesn't have a thermal_bind_params
structure and arguably it's better to pass the weight inside the
thermal_instance as it is specific to the bind of a cooling device to a
thermal zone parameter.

Core thermal code is fixed to populate the weight in the instance from
the thermal_bind_params, so platform code that was passing the weight
inside the thermal_bind_params continue to work seamlessly.

While we are at it, create a default value for the weight parameter for
those thermal zones that currently don't define it and remove the
hardcoded default in of-thermal.

Cc: Zhang Rui 
Cc: "Rafael J. Wysocki" 
Cc: Len Brown 
Cc: Peter Feuerer 
Cc: Darren Hart 
Cc: Eduardo Valentin 
Cc: Kukjin Kim 
Cc: Durgadoss R 
Signed-off-by: Kapileshwar Singh 
Signed-off-by: Eduardo Valentin

Documentation: thermal: document of_cpufreq_cooling_register()

2015-01-06T18:39:17+00:00

Commit 39d99cff76bf ("thermal: cpu_cooling: introduce
of_cpufreq_cooling_register") taught the cpu cooling device to register
devices that were linked to the device tree but didn't update the
cpu-cooling-api documentation.  Fix it.

Cc: Amit Daniel Kachhap 
Cc: Jonathan Corbet 
Cc: Zhang Rui 
Cc: Eduardo Valentin 
Signed-off-by: Javi Merino 
Signed-off-by: Eduardo Valentin