linux/Documentation/admin-guide/acpi/fan_performance_states.rst
Randy Dunlap ae99fb8baa Documentation/admin-guide/acpi: fix fan_performance_states.rst warnings
Fix Sphinx format warnings in fan_performace_states.rst
by adding indentation.

Documentation/admin-guide/acpi/fan_performance_states.rst:21: WARNING: Literal block ends without a blank line; unexpected unindent.
Documentation/admin-guide/acpi/fan_performance_states.rst:41: WARNING: Literal block expected; none found.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-02-20 10:50:43 +01:00

63 lines
2.2 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.