Re: [RFC PATCH v2 1/3] regulator: bindings: Add properties for coupled regulators

[Maciej Purski]

On 10/25/2017 02:59 PM, Rob Herring wrote:
> On Wed, Oct 25, 2017 at 2:31 AM, Maciej Purski <m.purski@xxxxxxxxxxx> wrote:
> > On 10/24/2017 08:58 PM, Rob Herring wrote:
> > > On Wed, Oct 18, 2017 at 02:47:00PM +0200, Maciej Purski wrote:
> > > > Some regulators require keeping their voltage spread below defined
> > > > max_spread.
> > > >
> > > > Add properties to provide information on regulators' coupling.
> > > >
> > > > Signed-off-by: Maciej Purski <m.purski@xxxxxxxxxxx>
> > > > ---
> > > >    Documentation/devicetree/bindings/regulator/regulator.txt | 4 ++++
> > > >    1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/regulator/regulator.txt
> > > > b/Documentation/devicetree/bindings/regulator/regulator.txt
> > > > index 378f6dc..6769565 100644
> > > > --- a/Documentation/devicetree/bindings/regulator/regulator.txt
> > > > +++ b/Documentation/devicetree/bindings/regulator/regulator.txt
> > > > @@ -60,6 +60,10 @@ Optional properties:
> > > >          0: Disable active discharge.
> > > >          1: Enable active discharge.
> > > >          Absence of this property will leave configuration to default.
> > > > +- regulator-coupled-with: Phandle to regulators with which the regulator
> > > > +  should be coupled. Allow up to 9 phandles.
> > >
> > >
> > > 9? Sounds like a driver detail and pretty arbitrary.
> > It's just a constant number that I defined as MAX_COUPLED, because in fact
> > there isn't any use-case yet for even more than two regulators so
> > MAX_COUPLED equal to 9 is a really high number. If you find it cleaner, I
> > can make this value variable.
>
> Just drop the statement. The OS simply needs to support however many
> there are for the h/w it supports.

Ok, I get this.

> > > Is this linkage 2-way meaning 2 coupled regulators both have links to
> > > the other one? If so, then what happens when you have a high number? If
> > > not, how does one decide which regulator has this property?
> >
> >
> > Yes, it is 2-way. When you have a high number, then each regulator should
> > have phandles to every other. So, if you have 3 regulators coupled, then
> > each one should have 2 phandles.
>
> Please add this to the description. That doesn't really seem ideal if
> you have a lot, but I somewhat doubt we'll see more than 2-3.
>
> Rob

I'll fix the description in the next version. Yes, I agree that we won't see 
more than 2-3 coupled regulators.

Best Regards,

Maciej Purski