Re: [PATCH v15 1/8] dt-bindings: mfd: Initial commit of silergy,sy7636a.yaml

Alistair Francis
2021-11-23T13:29:59Z

On Thu, Nov 18, 2021 at 7:40 AM Andreas Kemnade <andreas@kemnade.info> wrote:
>
> On Wed, 10 Nov 2021 22:29:41 +1000
> Alistair Francis <alistair@alistair23.me> wrote:
>
> > Initial support for the Silergy SY7636A Power Management chip
> > and regulator.
> >
> > Signed-off-by: Alistair Francis <alistair@alistair23.me>
> > Reviewed-by: Rob Herring <robh@kernel.org>
> > Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>
> > ---
> > .../bindings/mfd/silergy,sy7636a.yaml | 79 +++++++++++++++++++
> > 1 file changed, 79 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/mfd/silergy,sy7636a.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/mfd/silergy,sy7636a.yaml b/Documentation/devicetree/bindings/mfd/silergy,sy7636a.yaml
> > new file mode 100644
> > index 000000000000..0566f9498e2f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/mfd/silergy,sy7636a.yaml
> [...]
> > + regulators:
> > + type: object
> > +
> > + properties:
> > + compatible:
> > + const: silergy,sy7636a-regulator
> > +
> > + vcom:
> > + type: object
> > + $ref: /schemas/regulator/regulator.yaml#
> > + properties:
> > + regulator-name:
> > + const: vcom
> > +
> hmm, this is what? If I understand it correctly, vcom means some
> voltage for compensation. On other comparable pmics (e.g. TPS65185
> which has also a sane public datasheet, MAX17135) I have seen some
> methods to measure a voltage while the display is doing something
> defined and then program this voltage non-volatile for compensation
> during manufacturing.
>
> If I understand the code correctly all the bunch of voltages are
> powered up if this one is enabled.
> So at least a description should be suitable.
>
> The other comparable PMICs have at least regulators named VCOM, DISPLAY
> (controls several regulators, started with delays configured via
> registers) and V3P3. MAX17135 source can be found in NXP kernels,
> TPS65185 in Kobo vendor kernels.
>
> So I would expect to see something similar here and a description or at
> least not such a misleading name as vcom if it is for some reason not
> feasible to separate the regulators.

This is a vcom in the sense of voltage for compensation. We just
currently don't support setting the vcom.

I had a look at the Kobo code and this is similar to
https://github.com/akemnade/linux/blob/kobo/epdc-pmic-5.15/drivers/regulator/sy7636-regulator.c#L614

So I think that vcom is still the appropriate name for this.

Alistair

>
> Regards,
> Andreas