Re: [RFC PATCH v2 2/3] hwmon: (adt7475) fan stall prevention
From: Chris Packham
Date: Wed May 03 2017 - 16:45:14 EST
On 04/05/17 04:10, Guenter Roeck wrote:
> On Wed, May 03, 2017 at 12:40:08PM +1200, Chris Packham wrote:
>> By default adt7475 will stop the fans (pwm duty cycle 0%) when the
>> temperature drops past Tmin - hysteresis. Some systems want to keep the
>> fans moving even when the temperature drops so add new sysfs attributes
>> that configure the enhanced acoustics min 1-3 which allows the fans to
>> run at the minimum configure pwm duty cycle.
>> Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
>> Changes in v2:
>> - use pwmN_stall_dis as the attribute name. I think this describes the purpose
>> pretty well. I went with a new attribute instead of overloading
>> pwmN_auto_point1_pwm so this doesn't affect existing users.
>> Documentation/hwmon/adt7475 | 5 +++++
>> drivers/hwmon/adt7475.c | 50 +++++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 55 insertions(+)
>> diff --git a/Documentation/hwmon/adt7475 b/Documentation/hwmon/adt7475
>> index 0502f2b464e1..63507402cd4f 100644
>> --- a/Documentation/hwmon/adt7475
>> +++ b/Documentation/hwmon/adt7475
>> @@ -109,6 +109,11 @@ fan speed) is applied. PWM values range from 0 (off) to 255 (full speed).
>> Fan speed may be set to maximum when the temperature sensor associated with
>> the PWM control exceeds temp#_max.
>> +At Tmin - hysteresis the PWM output can either be off (0% duty cycle) or at the
>> +minimum (i.e. auto_point1_pwm). This behaviour be configured using the
>> +pwm[1-*]_stall_dis sysfs attribute. A value of 0 means the fans will shut off.
> That is really an awkward attribute name. I'll have to think about this some
I agree. The other thing I considered was "halt" and using inverted
logic so halt == 1 reflected the HW default of allowing fans to stop.