Hi Guenter, > On Fri, Dec 19, 2014 at 04:32:24PM +0100, Lukasz Majewski wrote: > > Hi Sjoerd, > > > > Thanks for your feedback and sorry for a late reply. > > > > > On Thu, 2014-12-18 at 11:13 +0100, Lukasz Majewski wrote: > > > > Several new properties to allow PWM fan working as a cooling > > > > device have been combined into this single commit. > > > > > > > > Signed-off-by: Lukasz Majewski <l.majewski@xxxxxxxxxxx> > > > > --- > > > > .../devicetree/bindings/hwmon/pwm-fan.txt | 28 > > > > ++++++++++++++++++++++ 1 file changed, 28 insertions(+) > > > > > > > > diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt > > > > b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt index > > > > 610757c..3877810 100644 --- > > > > a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt +++ > > > > b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt @@ -3,10 > > > > +3,38 @@ Bindings for a fan connected to the PWM lines Required > > > > properties: > > > > - compatible : "pwm-fan" > > > > - pwms : the PWM that is used to control the > > > > PWM fan +- cooling-pwm-values : PWM duty cycle values > > > > relative to > > > > + cooling-max-pwm-value correspondig > > > > to > > > > + proper cooling states > > > > +- default-pulse-width : Property specifying default pulse > > > > width for FAN > > > > + at system boot (zero to disable > > > > FAN on boot). > > > > + Allowed range is 0 to 255 > > > > > > The 0..255 range seems somewhat random. Would be nicer to either > > > use the approach of pwm-backlight (iotw, have the range go from > > > the first to the last entry of cooling-pwm-values) > > > > I'm OK to change the default-pulse-width to be similar to > > "default-brightness-level" (as it is in > > Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt) > > > > > or simply have be the duty > > > lenght in NS as entries instead of the current indirection. > > > > I'd prefer to keep the indirection - as it is utilized in the > > current pwm-fan.c driver. > > > FWIW, devicetree information is supposed to be implementation > independent. So this is a poor argument. Many other pwm drivers use the indirection - e.g. mentioned pwm-backlight. > > > > > Enabling pan to full RPM was the default behaviour in the current > > pwm-fan.c file. > > > > To be honest, there is no need to enable fan to full RPM speed in > > this board for following reasons: > > 1. In Odroid the FAN is optional (stacked on top of a heat sink) - > > very often it is just enough to only have the heat sink. > > > > 2. Odroid has thermal enabled by default and IMHO it would be more > > feasible to allow thermal to control fan from the very beginning. > > > > However, I can also understand if the policy for hwmon implies a > > rule to enable by default all fans to full RPM speed. > > > Why and how does that all suggest that the current default behavior > should be changed ? I wanted to avoid the unpleasant sound for full speed fan when thermal is not enabled by default. But as I said, I fully understand the policy and I would be happy to comply with it as thermal should reduce the fan speed anyway at boot time. > > Guenter -- Best regards, Lukasz Majewski Samsung R&D Institute Poland (SRPOL) | Linux Platform Group _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
