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Date:   Thu, 9 Jan 2020 08:10:47 +0100
From:   Andreas Klinger <ak@it-klinger.de>
To:     Rob Herring <robh@kernel.org>
Cc:     jic23@kernel.org, mark.rutland@arm.com, knaack.h@gmx.de,
        lars@metafoo.de, pmeerw@pmeerw.net, rpi-receiver@htl-steyr.ac.at,
        linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: devantech-srf04.yaml: add pm feature
Message-ID: <20200109071047.GA3043@arbad>
References: <20200102172749.v7ufupd32ytf7jda@arbad>
 <20200108165813.GA4472@bogus>
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Hi Rob,

see below.

Rob Herring <robh@kernel.org> schrieb am Mi, 08. Jan 10:58:
> On Thu, Jan 02, 2020 at 06:27:51PM +0100, Andreas Klinger wrote:
> > Add GPIO line and startup time for usage of power management
> > 
> > Signed-off-by: Andreas Klinger <ak@it-klinger.de>
> > ---
> >  .../bindings/iio/proximity/devantech-srf04.yaml          | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/proximity/devantech-srf04.yaml b/Documentation/devicetree/bindings/iio/proximity/devantech-srf04.yaml
> > index 4e80ea7c1475..b3fcb3b79485 100644
> > --- a/Documentation/devicetree/bindings/iio/proximity/devantech-srf04.yaml
> > +++ b/Documentation/devicetree/bindings/iio/proximity/devantech-srf04.yaml
> > @@ -51,6 +51,22 @@ properties:
> >        the time between two interrupts is measured in the driver.
> >      maxItems: 1
> >  
> > +  power-gpios:
> > +    description:
> > +      Definition of the GPIO for power management of connected peripheral
> > +      (output).
> > +      This GPIO can be used by the external hardware for power management.
> > +      When the device gets suspended it's switched off and when it resumes
> > +      it's switched on again. After some period of inactivity the driver
> > +      get suspended automatically (autosuspend feature).
> > +    maxItems: 1
> > +
> > +  startup-time-ms:
> 
> Why isn't this implied by the compatible string? 

Under the same trade name "SRF-04" there are many different sensors on the
market which are clones of the original one from Devantech. They are equipped
with different hardware components and they have a slightly different behavior,
such as the startup time. 

> 
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> 
> You can drop this for standard units. 
> 
> 0-2^32 is valid?

I can add boundaries here.

> 
> > +    description:
> > +      This is the startup time the device needs after a resume to be up and
> > +      running.
> > +
> >  required:
> >    - compatible
> >    - trig-gpios
> > -- 
> > 2.11.0

Andreas