Re: [PATCH v2 1/2] dt-bindings: regulator: rpi-panel-v2: Add required vcc-supply property

[Conor Dooley <conor@kernel.org>]

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On Mon, Sep 07, 2026 at 02:24:09PM +0100, Dave Stevenson wrote:
> Hi Shashank
> 
> (Apologies for the earlier HTML version of this - I thought I had my
> mail client under control)
> 
> On Mon, 7 Sept 2026 at 06:48, Shashank Maurya
> <shashank.maurya@oss.qualcomm.com> wrote:
> >
> > Add a vcc-supply property to the Raspberry Pi 7" touchscreen panel V2
> > regulator binding and mark it as required. The panel controller MCU
> > needs an external power rail to be supplied before any I2C communication
> > can take place.
> >
> > Signed-off-by: Shashank Maurya <shashank.maurya@oss.qualcomm.com>
> > ---
> >  .../regulator/raspberrypi,7inch-touchscreen-panel-regulator-v2.yaml  | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator-v2.yaml b/Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator-v2.yaml
> > index 37b9ed371b67..a6195e53be16 100644
> > --- a/Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator-v2.yaml
> > +++ b/Documentation/devicetree/bindings/regulator/raspberrypi,7inch-touchscreen-panel-regulator-v2.yaml
> > @@ -35,6 +35,9 @@ properties:
> >      const: 3
> >      description: See ../../pwm/pwm.yaml for description of the cell formats.
> >
> > +  vcc-supply:
> > +    description: Regulator supplying power to the panel controller.
> > +
> >  additionalProperties: false
> >
> >  required:
> > @@ -43,6 +46,7 @@ required:
> >    - gpio-controller
> >    - "#gpio-cells"
> >    - "#pwm-cells"
> > +  - vcc-supply
> 
> Adding a new property as "required" breaks all existing users. Adding
> it as optional would be reasonable.

It can be made required here, but never in the driver. If it's actually
required that something turn this on before the device can be used,
making it required is probably correct.

> 
>   Dave
> 
> >
> >  examples:
> >    - |
> > @@ -55,6 +59,7 @@ examples:
> >          gpio-controller;
> >          #gpio-cells = <2>;
> >          #pwm-cells = <3>;
> > +        vcc-supply = <&vcc_reg>;
> >        };
> >      };
> >
> >
> > --
> > 2.34.1
> >
> >

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