linux-kernel - Re: [PATCH v4 3/5] dt-bindings: hwmon: Document adt7475 invert-pwm property

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Message-ID: <20200221155259.GA11868@roeck-us.net>
Date:   Fri, 21 Feb 2020 07:52:59 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Chris Packham <chris.packham@...iedtelesis.co.nz>,
        Jean Delvare <jdelvare@...e.com>,
        Mark Rutland <mark.rutland@....com>,
        Linux HWMON List <linux-hwmon@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Logan Shaw <logan.shaw@...iedtelesis.co.nz>
Subject: Re: [PATCH v4 3/5] dt-bindings: hwmon: Document adt7475 invert-pwm
 property

On Fri, Feb 21, 2020 at 09:40:00AM -0600, Rob Herring wrote:
> On Thu, Feb 20, 2020 at 10:16 PM Chris Packham
> <chris.packham@...iedtelesis.co.nz> wrote:
> >
> > Add binding information for the invert-pwm property.
> >
> > Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> > ---
> >
> > Notes:
> >     Changes in v4:
> >     - use $ref uint32 and enum
> >     - add adi vendor prefix
> >
> >     Cahnges in v3:
> >     - new
> >
> >  Documentation/devicetree/bindings/hwmon/adt7475.yaml | 12 ++++++++++++
> >  1 file changed, 12 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/adt7475.yaml b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > index e40612ee075f..6a358b30586c 100644
> > --- a/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > +++ b/Documentation/devicetree/bindings/hwmon/adt7475.yaml
> > @@ -50,6 +50,17 @@ patternProperties:
> >       - $ref: /schemas/types.yaml#/definitions/uint32
> >       - enum: [0, 1]
> >
> > +  "^adi,invert-pwm[1-3]$":
> > +    description: |
> > +      Configures the pwm output to use inverted logic. If set to 1
> > +      the pwm uses a logic low output for 100% duty cycle. If set
> > +      to 0 the pwm uses a logic high output for 100% duty cycle.
> > +      If the property is absent the pwm retains it's configuration
> > +      from the bios/bootloader.
> 
> I believe we already have an inverted flag for consumers. That doesn't
> work if you don't have a consumer described in DT, but then the
> question is should you? Or is this something the user will want to
> configure from userspace.
> 

Normally that is a system property. It is difficult to imagine
that it would ever have to be configured from userspace at runtime.
Most of the time users won't have any idea, and the board datasheet
(if avaible) won't list such information.

Guenter