Re: [PATCH 2/3] dt-bindings: regulator: Add regulator-output binding

[Zev Weiss]

On Thu, Sep 29, 2022 at 02:27:20PM PDT, Zev Weiss wrote:
> On Thu, Sep 29, 2022 at 02:07:14PM PDT, Rob Herring wrote:
> > On Sun, Sep 25, 2022 at 03:03:18PM -0700, Zev Weiss wrote:
> > > This describes a power output supplied by a regulator, such as a
> > > power outlet on a power distribution unit (PDU).
> > >
> > > Signed-off-by: Zev Weiss <zev@xxxxxxxxxxxxxxxxx>
> > > ---
> > > .../bindings/regulator/regulator-output.yaml  | 47 +++++++++++++++++++
> > > 1 file changed, 47 insertions(+)
> > > create mode 100644 Documentation/devicetree/bindings/regulator/regulator-output.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/regulator/regulator-output.yaml b/Documentation/devicetree/bindings/regulator/regulator-output.yaml
> > > new file mode 100644
> > > index 000000000000..40953ec48e9e
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/regulator/regulator-output.yaml
> > > @@ -0,0 +1,47 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +
> > > +$id: http://devicetree.org/schemas/regulator/regulator-output.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Regulator output connector
> > > +
> > > +maintainers:
> > > +  - Zev Weiss <zev@xxxxxxxxxxxxxxxxx>
> > > +
> > > +description: |
> > > +  This describes a power output connector supplied by a regulator,
> > > +  such as a power outlet on a power distribution unit (PDU).  The
> > > +  connector may be standalone or merely one channel or set of pins
> > > +  within a ganged physical connector carrying multiple independent
> > > +  power outputs.
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: regulator-output
> > > +
> > > +  vout-supply:
> > > +    description:
> > > +      Phandle of the regulator supplying the output.
> > > +
> > > +  regulator-leave-on:
> > > +    description: |
> > > +      If the regulator is enabled when software relinquishes control
> > > +      of it (such as when shutting down) it should be left enabled
> > > +      instead of being turned off.
> > > +    type: boolean
> >
> > I'm not too sure about this one as there could be various times when
> > control is relinquished. It is userspace closing its access?
> > driver unbind? module unload? Does a bootloader pay attention to this?
> >
> > Rob
>
> Thanks for the feedback, Rob -- I'll admit I was a bit unsure how to 
> approach that, and this may well not be the right answer.  What I'm 
> really aiming for is an appropriate way to express that regulator 
> on/off state should only ever be changed by explicit (external, e.g. 
> userspace) request, never as any sort of default/automatic action.  
> The two obvious things to guard against there seem to be automatic 
> enablement during initialization and automatic disablement on de-init 
> (shutdown, unbind, etc.).  The former I think can be avoided by simply 
> not setting regulator-boot-on, so I added this as a corresponding 
> property to avoid the latter.
>
> I'm definitely open to suggestions for a better approach though.

Ping...

Would something like this be preferable as a more direct description of 
that?

  regulator-manually-controlled:
    description: |
      The regulator should never be enabled or disabled automatically,
      only when explicitly requested by an external actor (e.g.  
      userspace).
    type: boolean

That would leave the question of which property takes priority if both 
regulator-manually-controlled and regulator-boot-on are set -- should 
the binding document the answer to that?  (I personally don't have a 
strong opinion on which it should be.)

Thanks,
Zev