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. > > 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 ? Guenter -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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