linux-kernel - Re: [PATCH 4/7] dt-bindings: Input: introduce new clock vibrator bindings

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Date:   Mon, 9 Dec 2019 11:55:58 -0500
From:   Brian Masney <masneyb@...tation.org>
To:     Rob Herring <robh+dt@...nel.org>, Stephen Boyd <sboyd@...nel.org>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Mark Rutland <mark.rutland@....com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Linux Input <linux-input@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        thierry.reding@...il.com
Subject: Re: [PATCH 4/7] dt-bindings: Input: introduce new clock vibrator
 bindings

On Mon, Dec 09, 2019 at 10:16:26AM -0600, Rob Herring wrote:
> On Sun, Dec 8, 2019 at 6:54 PM Brian Masney <masneyb@...tation.org> wrote:
> >
> > On Thu, Dec 05, 2019 at 07:56:10AM -0600, Rob Herring wrote:
> > > On Wed, Dec 4, 2019 at 6:25 PM Brian Masney <masneyb@...tation.org> wrote:
> > > >
> > > > Add support for clock-based vibrator devices where the speed can be
> > > > controlled by changing the duty cycle.
> > > >
> > > > Signed-off-by: Brian Masney <masneyb@...tation.org>
> > > > ---
> > > >  .../bindings/input/clk-vibrator.yaml          | 60 +++++++++++++++++++
> > > >  1 file changed, 60 insertions(+)
> > > >  create mode 100644 Documentation/devicetree/bindings/input/clk-vibrator.yaml
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/input/clk-vibrator.yaml b/Documentation/devicetree/bindings/input/clk-vibrator.yaml
> > > > new file mode 100644
> > > > index 000000000000..2103a5694fad
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/input/clk-vibrator.yaml
> > > > @@ -0,0 +1,60 @@
> > > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > > +%YAML 1.2
> > > > +---
> > > > +$id: http://devicetree.org/schemas/bindings/input/clk-vibrator.yaml#
> > > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > > +
> > > > +title: Clock vibrator
> > > > +
> > > > +maintainers:
> > > > +  - Brian Masney <masneyb@...tation.org>
> > > > +
> > > > +description: |
> > > > +  Support for clock-based vibrator devices where the speed can be controlled
> > > > +  by changing the duty cycle.
> > > > +
> > > > +properties:
> > > > +  compatible:
> > > > +    const: clk-vibrator
> > > > +
> > > > +  clocks:
> > > > +    maxItems: 1
> > > > +
> > > > +  clock-names:
> > > > +    description: output clock that controls the speed
> > > > +    items:
> > > > +      - const: core
> > >
> > > No point in making up a name when there's only one clock, so drop.
> >
> > OK, will do.
> >
> > >
> > > > +
> > > > +  clock-frequency: true
> > >
> > > Given the frequency is variable, what does this mean in this case?
> >
> > The clock frequency is fixed. The duty cycle is what's variable.
> 
> That sounds like a PWM then...

Yes... See this message from Stephen with some more background
information about why this is in the clk subsystem:

https://lore.kernel.org/lkml/20190627234929.B78E520815@mail.kernel.org/

Brian