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Commit b39fe582 authored by Henrique de Moraes Holschuh's avatar Henrique de Moraes Holschuh Committed by Len Brown
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ACPI: thinkpad-acpi: improve fan control documentation 



Improve fan control documentation and fix one mistake.

Signed-off-by: default avatarHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent c573ddb9

Documentation/thinkpad-acpi.txt

+13 −5
Original line number Diff line number Diff line
@@ -795,15 +795,23 @@ Sysfs notes: 
The sysfs interface follows the hwmon subsystem guidelines for the most

part, and the exception is the fan safety watchdog.



Writes to any of the sysfs attributes may return the EINVAL error if

that operation is not supported in a given ThinkPad or if the parameter

is out-of-bounds, and EPERM if it is forbidden.  They may also return

EINTR (interrupted system call), and EIO (I/O error while trying to talk

to the firmware).



Features not yet implemented by the driver return ENOSYS.



hwmon device attribute pwm1_enable:

	0: PWM offline (fan is set to full-speed mode)

	1: Manual PWM control (use pwm1 to set fan level)

	2: Hardware PWM control (EC "auto" mode)

	3: reserved (Software PWM control, not implemented yet)



	Modes 0 and 2 are not supported by all ThinkPads, and the driver

	is not always able to detect this.  If it does know a mode is

	unsupported, it will return -EINVAL.

	Modes 0 and 2 are not supported by all ThinkPads, and the

	driver is not always able to detect this.  If it does know a

	mode is unsupported, it will return -EINVAL.



hwmon device attribute pwm1:

	Fan level, scaled from the firmware values of 0-7 to the hwmon
@@ -826,8 +834,8 @@ driver attribute fan_watchdog: 
To stop the fan: set pwm1 to zero, and pwm1_enable to 1.



To start the fan in a safe mode: set pwm1_enable to 2.  If that fails

with ENOTSUP, set it to 1 and set pwm1 to at least 128 (255 would be the

safest choice, though).

with EINVAL, try to set pwm1_enable to 1 and pwm1 to at least 128 (255

would be the safest choice, though).





EXPERIMENTAL: WAN -- /proc/acpi/ibm/wan