From f8d0c19a93cea3a26a90f2462295e1e01a4cd250 Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Wed, 14 Feb 2007 21:15:02 +0100 Subject: hwmon/it87: Add PWM base frequency control Let the user select the base PWM frequency when using the it87 hardware monitoring driver. Different frequencies can give better control on some fans. Also update the documentation to mention the PWM frequency control files, with misc cleanups to the PWM section. Signed-off-by: Jean Delvare --- Documentation/hwmon/it87 | 10 ++++++++++ Documentation/hwmon/sysfs-interface | 15 ++++++++++----- 2 files changed, 20 insertions(+), 5 deletions(-) (limited to 'Documentation/hwmon') diff --git a/Documentation/hwmon/it87 b/Documentation/hwmon/it87 index 74a80992d237..c0528d6f9ace 100644 --- a/Documentation/hwmon/it87 +++ b/Documentation/hwmon/it87 @@ -135,6 +135,16 @@ Give 0 for unused sensor. Any other value is invalid. To configure this at startup, consult lm_sensors's /etc/sensors.conf. (2 = thermistor; 3 = thermal diode) + +Fan speed control +----------------- + The fan speed control features are limited to manual PWM mode. Automatic "Smart Guardian" mode control handling is not implemented. However if you want to go for "manual mode" just write 1 to pwmN_enable. + +If you are only able to control the fan speed with very small PWM values, +try lowering the PWM base frequency (pwm1_freq). Depending on the fan, +it may give you a somewhat greater control range. The same frequency is +used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are +read-only. diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface index efef3b962cd3..d73d2e8c7534 100644 --- a/Documentation/hwmon/sysfs-interface +++ b/Documentation/hwmon/sysfs-interface @@ -166,16 +166,21 @@ pwm[1-*] Pulse width modulation fan control. pwm[1-*]_enable Switch PWM on and off. - Not always present even if fan*_pwm is. + Not always present even if pwmN is. 0: turn off 1: turn on in manual mode 2+: turn on in automatic mode - Check individual chip documentation files for automatic mode details. + Check individual chip documentation files for automatic mode + details. RW -pwm[1-*]_mode - 0: DC mode - 1: PWM mode +pwm[1-*]_mode 0: DC mode (direct current) + 1: PWM mode (pulse-width modulation) + RW + +pwm[1-*]_freq Base PWM frequency in Hz. + Only possibly available when pwmN_mode is PWM, but not always + present even then. RW pwm[1-*]_auto_channels_temp -- cgit v1.2.1