Re: [PATCH v2] dt-binding: eeprom: at24: add supply properties

[Rob Herring <robh@kernel.org>]

On Thu, Oct 24, 2019 at 06:32:38PM +0900, Tomasz Figa wrote:
> On Thu, Oct 24, 2019 at 5:40 PM Bartosz Golaszewski
> <bgolaszewski@baylibre.com> wrote:
> >
> > czw., 24 paź 2019 o 09:02 Tomasz Figa <tfiga@chromium.org> napisał(a):
> > >
> > > On Thu, Oct 24, 2019 at 3:22 PM Bartosz Golaszewski
> > > <bgolaszewski@baylibre.com> wrote:
> > > >
> > > > pt., 18 paź 2019 o 10:26 Bibby Hsieh <bibby.hsieh@mediatek.com> napisał(a):
> > > > >
> > > > > In some platforms, they disable the power-supply of eeprom and i2c due
> > > > > to power consumption reduction.
> > > > >
> > > > > This patch add two supply properties: vcc-supply, i2c-supply.
> > > > >
> > > > > Changes since v1:
> > > > >  - change supply name
> > > > >  - rebase to next
> > > > >
> > > > > Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
> > > > > ---
> > > > >  Documentation/devicetree/bindings/eeprom/at24.yaml | 8 ++++++++
> > > > >  1 file changed, 8 insertions(+)
> > > > >
> > > > > diff --git a/Documentation/devicetree/bindings/eeprom/at24.yaml b/Documentation/devicetree/bindings/eeprom/at24.yaml
> > > > > index e8778560d966..578487a5d9b7 100644
> > > > > --- a/Documentation/devicetree/bindings/eeprom/at24.yaml
> > > > > +++ b/Documentation/devicetree/bindings/eeprom/at24.yaml
> > > > > @@ -167,6 +167,14 @@ properties:
> > > > >      minimum: 1
> > > > >      maximum: 8
> > > > >
> > > > > +  vcc-supply:
> > > > > +    description:
> > > > > +      phandle of the regulator that provides the supply voltage.
> > > > > +
> > > > > +  i2c-sypply:
> > > > > +    description:
> > > > > +      phandle to the regulator that provides power to i2c.
> > > > > +
> > > >
> > > > Something was bothering me about this patch so I came back to take a
> > > > look. Can you explain what i2c actually stands for in this doc? I hope
> > > > I'm misinterpreting something and it isn't that the driver disables
> > > > the regulator powering the i2c bus controller?
> > >
> > > In our case it's the regulator that the I2C bus is pulled up to.
> > >
> >
> > Then it has nothing to do with a generic EEPROM driver IMO. I think
> > you need to add the control for this regulator to your i2c controller
> > driver and create a power domain where the EEPROM would be lower in
> > hierarchy.
> 
> While I agree that the generic EEPROM driver may not be the best place
> to do it, neither is a driver for a specific SoC i2c controller. The
> hardware design is not specific to any particular i2c controller.
> 
> Perhaps we need the generic i2c core to take into account an
> i2c-supply? Wolfram, any thoughts on this?

Sounds good to me. Maybe 'bus-supply' instead to indicate it's supposed 
to be for the bus and not other things. It should reside in the I2C 
controller's node (or mux ports) though.

Rob