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

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@nvidia.com>
>> CC: Douglas Anderson <dianders@chromium.org>
>> CC: Aleksandr Frid <afrid@nvidia.com>
>>
>> ---
>> 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.

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