Re: [PATCH v2 0/9] regulator: pwm-regulator: Introduce continuous-mode

Lee Jones
2015-07-09T17:20:53Z

On Thu, 09 Jul 2015, Doug Anderson wrote:
> On Thu, Jul 9, 2015 at 6:14 AM, Boris Brezillon
> <boris.brezillon@free-electrons.com> wrote:
> >> If you wish to add a 3rd mode, then I'm sure Mark will accept
> >> submissions, but I think what you are suggesting would be pretty
> >> complex and out-of-scope of what this patch-set is trying to achieve.
> >
> > Okay, still don't get the need to add a new mode which is almost doing
> > the same thing when we could have implemented it in a generic way in the
> > first place. But if your version has already been accepted then I think
> > I'll have to propose a new mode :-/.
> >
> >>
> >> As a side note, then if the voltage isn't directly proportional to the
> >> duty cycle on a large scale i.e. max => min, then it will not likely
> >> be very accurate between say table entries 1 => 2, or 4 => 5, etc.
> >>
> >> What I suggest you do in your case is provide a larger table with all
> >> of the values you find interesting, as it sounds like your PWM
> >> regulator isn't doing what one would normally expect.
> >
> > Well, I do not exactly agree here. Yes if you want to have a precise
> > mapping you'll have to add more entries in your voltage table, but
> > using linear interpolation between two points can be precise enough on
> > some ranges and prevent one to define a complete voltage table in the
> > DT.
> >
> > Doug, could give more details about the regulator used on the veyron
> > board ?
>
> There's no need for a new mode as far as veyron is concerned. The pwm
> regulator on veyron (as far as I understand it) acts the way that Lee
> describes. Try doing the math on the values in the table and you
> should see that it's as linear as it can be while still using integral
> duty cycles.
>
> Originally I only suggested using "linear interpolation" because:
>
> * It meant no bindings change, which is always nice to avoid.
>
> * It meant that old devices got this new mode, which is probably the
> right thing anyway (I think). Maybe nobody has published DTS files
> with pwm-regulator, so the point is moot.

Great news. This means that you provide the voltage the regulator
will provide with 0% duty cycle and 100% duty cycle and you're hot to
trot. No further configuration/bindings required.

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
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