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| author | Henrique de Moraes Holschuh <hmh@hmh.eng.br> | 2007-04-27 22:00:13 -0300 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2007-04-28 21:41:19 -0400 |
| commit | b39fe582eb9252dca9a62f7135bcad2e486083e5 (patch) | |
| tree | 597cc56e18c4fe628d99c6f1c9d7470126d50dc7 /Documentation | |
| parent | c573ddb998456a89a5ccb83a922d2c8ba18484a6 (diff) | |
| download | lwn-b39fe582eb9252dca9a62f7135bcad2e486083e5.tar.gz lwn-b39fe582eb9252dca9a62f7135bcad2e486083e5.zip | |
ACPI: thinkpad-acpi: improve fan control documentation
Improve fan control documentation and fix one mistake.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/thinkpad-acpi.txt | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/Documentation/thinkpad-acpi.txt b/Documentation/thinkpad-acpi.txt index bca50d78a425..e3ad7a4f7402 100644 --- a/Documentation/thinkpad-acpi.txt +++ b/Documentation/thinkpad-acpi.txt @@ -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 |