mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-25 21:24:08 +08:00
0750b8fcf3
Add documentation for the newly added attributes: fine_grain_control fan_speed_rpm Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
91 lines
3.3 KiB
ReStructuredText
91 lines
3.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
===========================
|
|
ACPI Fan Performance States
|
|
===========================
|
|
|
|
When the optional _FPS object is present under an ACPI device representing a
|
|
fan (for example, PNP0C0B or INT3404), the ACPI fan driver creates additional
|
|
"state*" attributes in the sysfs directory of the ACPI device in question.
|
|
These attributes list properties of fan performance states.
|
|
|
|
For more information on _FPS refer to the ACPI specification at:
|
|
|
|
http://uefi.org/specifications
|
|
|
|
For instance, the contents of the INT3404 ACPI device sysfs directory
|
|
may look as follows::
|
|
|
|
$ ls -l /sys/bus/acpi/devices/INT3404:00/
|
|
total 0
|
|
...
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state0
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state1
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state10
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state11
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state2
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state3
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state4
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state5
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state6
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state7
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state8
|
|
-r--r--r-- 1 root root 4096 Dec 13 20:38 state9
|
|
-r--r--r-- 1 root root 4096 Dec 13 01:00 status
|
|
...
|
|
|
|
where each of the "state*" files represents one performance state of the fan
|
|
and contains a colon-separated list of 5 integer numbers (fields) with the
|
|
following interpretation::
|
|
|
|
control_percent:trip_point_index:speed_rpm:noise_level_mdb:power_mw
|
|
|
|
* ``control_percent``: The percent value to be used to set the fan speed to a
|
|
specific level using the _FSL object (0-100).
|
|
|
|
* ``trip_point_index``: The active cooling trip point number that corresponds
|
|
to this performance state (0-9).
|
|
|
|
* ``speed_rpm``: Speed of the fan in rotations per minute.
|
|
|
|
* ``noise_level_mdb``: Audible noise emitted by the fan in this state in
|
|
millidecibels.
|
|
|
|
* ``power_mw``: Power draw of the fan in this state in milliwatts.
|
|
|
|
For example::
|
|
|
|
$cat /sys/bus/acpi/devices/INT3404:00/state1
|
|
25:0:3200:12500:1250
|
|
|
|
When a given field is not populated or its value provided by the platform
|
|
firmware is invalid, the "not-defined" string is shown instead of the value.
|
|
|
|
ACPI Fan Fine Grain Control
|
|
=============================
|
|
|
|
When _FIF object specifies support for fine grain control, then fan speed
|
|
can be set from 0 to 100% with the recommended minimum "step size" via
|
|
_FSL object. User can adjust fan speed using thermal sysfs cooling device.
|
|
|
|
Here use can look at fan performance states for a reference speed (speed_rpm)
|
|
and set it by changing cooling device cur_state. If the fine grain control
|
|
is supported then user can also adjust to some other speeds which are
|
|
not defined in the performance states.
|
|
|
|
The support of fine grain control is presented via sysfs attribute
|
|
"fine_grain_control". If fine grain control is present, this attribute
|
|
will show "1" otherwise "0".
|
|
|
|
This sysfs attribute is presented in the same directory as performance states.
|
|
|
|
ACPI Fan Performance Feedback
|
|
=============================
|
|
|
|
The optional _FST object provides status information for the fan device.
|
|
This includes field to provide current fan speed in revolutions per minute
|
|
at which the fan is rotating.
|
|
|
|
This speed is presented in the sysfs using the attribute "fan_speed_rpm",
|
|
in the same directory as performance states.
|