linux-kernel - Re: [PATCH 3/3] dt-bindings: regulator: add regulator-fixed-clock binding

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Message-ID: <e64429ba4b86411da1741ab54176fb5b4b7a36de.camel@toradex.com>
Date:   Wed, 4 Sep 2019 08:07:47 +0000
From:   Philippe Schenker <philippe.schenker@...adex.com>
To:     "robh+dt@...nel.org" <robh+dt@...nel.org>
CC:     Max Krummenacher <max.krummenacher@...adex.com>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        Luka Pivk <luka.pivk@...adex.com>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Stefan Agner <stefan.agner@...adex.com>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "mark.rutland@....com" <mark.rutland@....com>
Subject: Re: [PATCH 3/3] dt-bindings: regulator: add regulator-fixed-clock
 binding

On Tue, 2019-09-03 at 09:45 +0100, Rob Herring wrote:
> On Tue, Sep 3, 2019 at 9:03 AM Philippe Schenker
> <philippe.schenker@...adex.com> wrote:
> > This adds the documentation to the compatible regulator-fixed-clock
> 
> Please explain what that is in this patch.

Hi Rob and thanks for your comments. I will change this commit message
for a possible v2 into this:

This adds the documentation to the compatible regulator-fixed-clock.
This binding is a special binding of regulator-fixed and adds the
ability to add a clock to regulator-fixed, so the regulator can be
enabled and disabled with that clock.
If the special compatible regulator-fixed-clock is used it is mandatory
to supply a clock.

> > 
> 
> > Signed-off-by: Philippe Schenker <philippe.schenker@...adex.com>
> > 
> > ---
> > 
> >  .../bindings/regulator/fixed-regulator.yaml    | 18
> > +++++++++++++++++-
> >  1 file changed, 17 insertions(+), 1 deletion(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/regulator/fixed-
> > regulator.yaml b/Documentation/devicetree/bindings/regulator/fixed-
> > regulator.yaml
> > index a650b457085d..5fd081e80b43 100644
> > --- a/Documentation/devicetree/bindings/regulator/fixed-
> > regulator.yaml
> > +++ b/Documentation/devicetree/bindings/regulator/fixed-
> > regulator.yaml
> > @@ -19,9 +19,19 @@ description:
> >  allOf:
> >    - $ref: "regulator.yaml#"
> > 
> > +select:
> > +  properties:
> > +    compatible:
> > +      contains:
> > +        const: regulator-fixed-clock
> > +  required:
> > +    - clocks
> 
> You don't need this.
> 
> If you add a new compatible, then this should probably be a new schema
> doc. Is the 'gpio' property valid in this case as if a clock is the
> enable, can you also have a gpio enable? That said, it seems like the
> new compatible is only for validating the DT in the driver. You could
> just use a clock if present and default to current behavior if not.
> It's not the kernel's job to validate DTs.

The gpio property is valid with this compatible. I added regulator-
fixed-clock to regulator-fixed hence I also don't want to create a new
schema file.

With the above select statement I wanted to state clocks as required
when the compatible regulator-fixed-clock is given.

> 
> >  properties:
> >    compatible:
> > -    const: regulator-fixed
> > +    items:
> > +      - const: regulator-fixed
> > +      - const: regulator-fixed-clock
> 
> This says you must have 'compatible = "regulator-fixed",
> "regulator-fixed-clock";'.
> 
> What you want is:
> 
> enum:
>   - regulator-fixed
>   - regulator-fixed-clock

Thanks, this was exactly what I wanted to do.

> 
> >    regulator-name: true
> > 
> > @@ -29,6 +39,12 @@ properties:
> >      description: gpio to use for enable control
> >      maxItems: 1
> > 
> > +  clocks:
> > +    description:
> > +      clock to use for enable control. This binding is only
> > available if
> > +      the compatible is chosen to regulator-fixed-clock. The clock
> > binding
> > +      is mandatory if compatible is chosen to regulator-fixed-
> > clock.
> 
> Need to define how many clocks (maxItems: 1).

Will do for a possible v2. I want to wait what Mark Brown says about the
addition in general, maybe I have to change all over how this speciality
is added into regulator subsystem and therefore also the binding will
change.

Philippe
> 
> > +
> >    startup-delay-us:
> >      description: startup time in microseconds
> >      $ref: /schemas/types.yaml#/definitions/uint32
> > --
> > 2.23.0
> >