admin-guide/acpi/fan_performance_states.rst

1 .. SPDX-License-Identifier: GPL-2.0
4 ACPI Fan Performance States
8 fan (for example, PNP0C0B or INT3404), the ACPI fan driver creates additional
10 These attributes list properties of fan performance states.
19  $ ls -l /sys/bus/acpi/devices/INT3404:00/
22  -r--r--r-- 1 root root 4096 Dec 13 20:38 state0
23  -r--r--r-- 1 root root 4096 Dec 13 20:38 state1
24  -r--r--r-- 1 root root 4096 Dec 13 20:38 state10
25  -r--r--r-- 1 root root 4096 Dec 13 20:38 state11
26  -r--r--r-- 1 root root 4096 Dec 13 20:38 state2
27  -r--r--r-- 1 root root 4096 Dec 13 20:38 state3
28  -r--r--r-- 1 root root 4096 Dec 13 20:38 state4
29  -r--r--r-- 1 root root 4096 Dec 13 20:38 state5
30  -r--r--r-- 1 root root 4096 Dec 13 20:38 state6
31  -r--r--r-- 1 root root 4096 Dec 13 20:38 state7
32  -r--r--r-- 1 root root 4096 Dec 13 20:38 state8
33  -r--r--r-- 1 root root 4096 Dec 13 20:38 state9
34  -r--r--r-- 1 root root 4096 Dec 13 01:00 status
37 where each of the "state*" files represents one performance state of the fan
38 and contains a colon-separated list of 5 integer numbers (fields) with the
43 * ``control_percent``: The percent value to be used to set the fan speed to a
44   specific level using the _FSL object (0-100).
47   to this performance state (0-9).
49 * ``speed_rpm``: Speed of the fan in rotations per minute.
51 * ``noise_level_mdb``: Audible noise emitted by the fan in this state in
54 * ``power_mw``: Power draw of the fan in this state in milliwatts.
62 firmware is invalid, the "not-defined" string is shown instead of the value.
64 ACPI Fan Fine Grain Control
67 When _FIF object specifies support for fine grain control, then fan speed
69 _FSL object. User can adjust fan speed using thermal sysfs cooling device.
71 Here use can look at fan performance states for a reference speed (speed_rpm)
78 will show "1" otherwise "0".
82 ACPI Fan Performance Feedback
85 The optional _FST object provides status information for the fan device.
86 This includes field to provide current fan speed in revolutions per minute
87 at which the fan is rotating.