Re: [PATCH V2 1/2] regulator: pwm: DT: Add ramp delay for exponential voltage transition

[Laxman Dewangan]

On Monday 21 November 2016 09:47 PM, Rob Herring wrote:
> On Fri, Nov 18, 2016 at 08:05:55PM +0530, Laxman Dewangan wrote:
> > Some PWM regulator has the exponential transition in voltage change as
> > opposite to fixed slew-rate linear transition on other regulators.
> > For such PWM regulators, add the property to tell that voltage change
> > is exponential and having fixed delay for any level of change.
> >
> > Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
> > CC: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > CC: Aleksandr Frid <afrid@xxxxxxxxxx>
> >
> > ---
> > This patch is continuation of discussion on patch
> > 	regulator: pwm: Fix regulator ramp delay for continuous mode
> > https://patchwork.kernel.org/patch/9216857/
> > where is it discussed to have separate property for PWM which has
> > exponential voltage transition.
> >
> > Changes from V1:
> > - Pass the flag to tell that voltage ramp is exponential instead of
> >    providing delay.
> > ---
> >   .../devicetree/bindings/regulator/pwm-regulator.txt          | 12 ++++++++++++
> >   1 file changed, 12 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> > index 3aeba9f..2d9ef3a 100644
> > --- a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> > +++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt
> > @@ -54,6 +54,18 @@ Optional properties:
> >   --------------------
> >   - enable-gpios:		GPIO to use to enable/disable the regulator
> >   
> > +- voltage-ramp-exponential: Boolean, Some of PWM regulator has the exponential
> > +			transition in voltage ramp as opposite to fixed
> > +			slew-rate linear transition on other regulators.
> > +			For such PWM regulator, presence of this property will
> > +			tell that value of the regulator ramp delay provided by
> > +			DT property "regulator-ramp-delay" is exponential and
> > +			fixed delay for any voltage level change.
> > +			If PWM regulator supports the fixed linear slew rate
> > +			then this property should be absent from DT node and
> > +			property "regulator-ramp-delay" is used as linear slew
> > +			rate.
> Sorry, but on further thought, I don't think we should mix different
> units for the same property. Also, the fact that the ramp is exponential
> is irrelevant. You just want an absolute delay time rather than a rate,
> right? So instead, how about just "regulator-ramp-time-us". Roughly what
> you had in v1, but not PWM specific.

Can we say "regulator-settling-time-us" and make it generic i.e. part of 
the regulator core instead of PWM regulator specific?

So no change for "regulator-ramp-delay".
new property "regulator-settling-time-us" for fixed settling time in any 
voltage level change.