Re: [PATCH RFC 1/3] DT: add binding for MXS regulator

[Stefan Wahren]

Hi Mark,

Am 09.09.2014 19:59, schrieb Mark Rutland:
> On Sun, Sep 07, 2014 at 12:37:47PM +0100, Stefan Wahren wrote:
> > This patch adds the Device tree bindings for the Freescale MXS on-chip
> > regulators.
> >
> > Signed-off-by: Stefan Wahren <stefan.wahren@xxxxxxxx>
> > ---
> >   .../bindings/regulator/mxs-regulator.txt           | 38 ++++++++++++++++++++++
> >   1 file changed, 38 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/regulator/mxs-regulator.txt
> >
> > diff --git a/Documentation/devicetree/bindings/regulator/mxs-regulator.txt b/Documentation/devicetree/bindings/regulator/mxs-regulator.txt
> > new file mode 100644
> > index 0000000..c3226cc
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/regulator/mxs-regulator.txt
> > @@ -0,0 +1,38 @@
> > +MXS regulators
> > +
> > +Required node properties:
> > +- compatible: Should be "fsl,<soc>-power", where soc is "imx23" or "imx28"
> > +- reg: Offset and length of the register set for the device
>
> We require #address-cells and #size-cells if the child nodes have reg
> entries.

okay.

> > +
> > +Required regulator properties:
> > +- compatible: Must be "fsl,mxs-regulator"
> > +- reg: Offset of the register set for the regulator
>
> Is this the offset or the absolute physical address?
>
> The example seems to be absolute.

You are right, the description is wrong.

> > +- mxs-max-reg-val: Maximum value of this register
>
> What does this even mean? What's the format?
>
> Is this not implied by standard properties like regulator-max-microvolt?

Unfortunately not as long the step size in microvolt isn't defined. The 
parameter defines the register value in hex corresponding to 
regulator-max-microvolt.

step size = (regulator-max-microvolt - regulator-min-microvolt) / 
mxs-max-reg-val

May be i missed or understand something wrong?

> > +Optional regulator properties:
> > +- mxs-default-microvolt: initial voltage of the regulator
>
> Why is this necessary?

The original driver from Freescale set the MX28 regulator vddio to 3.38 
V during registering. I think that is ugly to implement in the driver 
part, so i add a more general property in the devicetree binding.

> Mark.

Stefan
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