From cdcaeceb74ff3686eb25de6812870fbc765c3c39 Mon Sep 17 00:00:00 2001 From: Guenter Roeck Date: Tue, 4 Dec 2012 09:04:52 -0800 Subject: hwmon: (nct6775) Add support for automatic fan control Signed-off-by: Guenter Roeck --- Documentation/hwmon/nct6775 | 69 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) (limited to 'Documentation') diff --git a/Documentation/hwmon/nct6775 b/Documentation/hwmon/nct6775 index 7c9f1d303913..b4fe6bc4d371 100644 --- a/Documentation/hwmon/nct6775 +++ b/Documentation/hwmon/nct6775 @@ -87,6 +87,75 @@ pwm[1-5]_mode - controls if output is PWM or DC level * 0 DC output * 1 PWM output +Common fan control attributes +----------------------------- + +pwm[1-5]_temp_sel Temperature source. Value is temperature sensor index. + For example, select '1' for temp1_input. + +Thermal Cruise mode (2) +----------------------- + +If the temperature is in the range defined by: + +pwm[1-5]_target_temp Target temperature, unit millidegree Celsius + (range 0 - 127000) +pwm[1-5]_temp_tolerance + Target temperature tolerance, unit millidegree Celsius + +there are no changes to fan speed. Once the temperature leaves the interval, fan +speed increases (if temperature is higher that desired) or decreases (if +temperature is lower than desired), using the following limits and time +intervals. + +pwm[1-5]_start fan pwm start value (range 1 - 255), to start fan + when the temperature is above defined range. +pwm[1-5]_floor lowest fan pwm (range 0 - 255) if temperature is below + the defined range. If set to 0, the fan is expected to + stop if the temperature is below the defined range. +pwm[1-5]_step_up_time milliseconds before fan speed is increased +pwm[1-5]_step_down_time milliseconds before fan speed is decreased +pwm[1-5]_stop_time how many milliseconds must elapse to switch + corresponding fan off (when the temperature was below + defined range). + +Speed Cruise mode (3) +--------------------- + +This modes tries to keep the fan speed constant. + +fan[1-5]_target Target fan speed +fan[1-5]_tolerance + Target speed tolerance + + +Untested; use at your own risk. + +Smart Fan IV mode (5) +--------------------- + +This mode offers multiple slopes to control the fan speed. The slopes can be +controlled by setting the pwm and temperature attributes. When the temperature +rises, the chip will calculate the DC/PWM output based on the current slope. +There are up to seven data points depending on the chip type. Subsequent data +points should be set to higher temperatures and higher pwm values to achieve +higher fan speeds with increasing temperature. The last data point reflects +critical temperature mode, in which the fans should run at full speed. + +pwm[1-5]_auto_point[1-7]_pwm + pwm value to be set if temperature reaches matching + temperature range. +pwm[1-5]_auto_point[1-7]_temp + Temperature over which the matching pwm is enabled. +pwm[1-5]_temp_tolerance + Temperature tolerance, unit millidegree Celsius +pwm[1-5]_crit_temp_tolerance + Temperature tolerance for critical temperature, + unit millidegree Celsius + +pwm[1-5]_step_up_time milliseconds before fan speed is increased +pwm[1-5]_step_down_time milliseconds before fan speed is decreased + Usage Notes ----------- -- cgit v1.2.3