On Thu, 09 Jul 2015, Doug Anderson wrote: > On Thu, Jul 9, 2015 at 6:14 AM, Boris Brezillon > <[email protected]> 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 Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
