Added documentation for performance states information for the ACPI Fan object. Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@xxxxxxxxxxxxxxx> --- .../acpi/fan_performance_states.rst | 65 +++++++++++++++++++ Documentation/admin-guide/acpi/index.rst | 1 + 2 files changed, 66 insertions(+) create mode 100644 Documentation/admin-guide/acpi/fan_performance_states.rst diff --git a/Documentation/admin-guide/acpi/fan_performance_states.rst b/Documentation/admin-guide/acpi/fan_performance_states.rst new file mode 100644 index 000000000000..91f10738e158 --- /dev/null +++ b/Documentation/admin-guide/acpi/fan_performance_states.rst @@ -0,0 +1,65 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=========================== +ACPI Fan Performance States +=========================== + +When the optional object _FPS is present for ACPI devices PNP0C0B or INT3404, +additional attributes are displayed under acpi device object. These attributes +display information about each performance state. + +For more details about ACPI Fan _FPS please refer to the ACPI specification at: + +http://uefi.org/specifications + +Example display for INT3404 ACPI device folder:: + + $ 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 + ... + ... + +In the above example, each of the state* attribute represent one performance +state. Each performance state contains information about the properties of a +state in the following format: + +control_percent:trip_point_index:speed_rpm:noise_level_mdb:power_mw + +For example:: + + $cat /sys/bus/acpi/devices/INT3404:00/state1 + 25:0:3200:12500:1250 + +Description of properties: + +* control_percent: Indicates the value to be used to set the fan speed to a +specific level using the _FSL object. The value here is from 0-100 percent. + +* trip_point_index: The active cooling trip point number that corresponds to this +performance state. The range is from 0-9. + +* speed_rpm: Indicates the speed of the fan in revolutions per minute. + +* noise_level_mdb: Indicates the audible noise emitted by the fan. By the +specification the value represents the noise in 10ths of decibels. Here +it is multiplied with 100 to present in milli-db, to avoid loss of +precision. + +* power_mw: Indicates the power consumption in milliwatts. + +When the fields are not populated or invalid in the configuration, +"not-defined" is displayed. + diff --git a/Documentation/admin-guide/acpi/index.rst b/Documentation/admin-guide/acpi/index.rst index 4d13eeea1eca..71277689ad97 100644 --- a/Documentation/admin-guide/acpi/index.rst +++ b/Documentation/admin-guide/acpi/index.rst @@ -12,3 +12,4 @@ the Linux ACPI support. dsdt-override ssdt-overlays cppc_sysfs + fan_performance_states -- 2.17.2
