linux-kernel - Re: [PATCH 2/3] dt-bindings: iio: gyro: adxrs290: Add required interrupts property

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Message-ID: <CAEtfd9Z51qm29zECBzQrRGoiL5SuVJ6_=ZMA98gSCxEY6-CH1g@mail.gmail.com>
Date:   Thu, 3 Sep 2020 18:16:28 +0530
From:   Nishant Malpani <nish.malpani25@...il.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        "Bogdan, Dragos" <dragos.bogdan@...log.com>,
        Darius <darius.berghe@...log.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>
Subject: Re: [PATCH 2/3] dt-bindings: iio: gyro: adxrs290: Add required
 interrupts property

Hello,

On Sat, Aug 29, 2020 at 10:18 PM Jonathan Cameron <jic23@...nel.org> wrote:
>
> On Tue, 25 Aug 2020 18:17:10 +0530
> Nishant Malpani <nish.malpani25@...il.com> wrote:
>
> > Append 'interrupts' as a required property and provide a suitable example
> > for using a GPIO interrupt line.
> >
> > Signed-off-by: Nishant Malpani <nish.malpani25@...il.com>
> Hi Nishant,
>
> I don't understand why the interrupt is 'required'.  Also note you should
> never be adding required properties to an existing binding.  It's possible
> someone already used the binding as it stands and shipped a board with
> it burnt in a firmware. (bit unlikely but you never know!)
>
> Jonathan
>

You're right; I hadn't thought of it that way. Will remove the
'interrupts' property from the 'required' ist in v2.

> > ---
> >  .../devicetree/bindings/iio/gyroscope/adi,adxrs290.yaml   | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/iio/gyroscope/adi,adxrs290.yaml b/Documentation/devicetree/bindings/iio/gyroscope/adi,adxrs290.yaml
> > index 61adb2c2454b..cae593dd1ba7 100644
> > --- a/Documentation/devicetree/bindings/iio/gyroscope/adi,adxrs290.yaml
> > +++ b/Documentation/devicetree/bindings/iio/gyroscope/adi,adxrs290.yaml
> > @@ -28,17 +28,23 @@ properties:
> >
> >    spi-cpha: true
> >
> > +  interrupts:
> > +    maxItems: 1
> > +
> >  required:
> >    - compatible
> >    - reg
> >    - spi-max-frequency
> >    - spi-cpol
> >    - spi-cpha
> > +  - interrupts
>
> Why?  Device works fine without one being supplied.
> It's not uncommon on embedded boards to not wire up interrupts
> due to a lack of pins and just rely on polling.
>

I was under the impression that the triggered-buffer way of capturing
data would more reasonable to the consumers of a gyroscope. But what
you point out makes total sense. Thanks for pointing out. Will fix it
in v2.

With regards,
Nishant Malpani

> >
> >  additionalProperties: false
> >
> >  examples:
> >    - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> >      spi {
> >          #address-cells = <1>;
> >          #size-cells = <0>;
> > @@ -48,6 +54,8 @@ examples:
> >                     spi-max-frequency = <5000000>;
> >                     spi-cpol;
> >                     spi-cpha;
> > +                   interrupt-parent = <&gpio>;
> > +                   interrupts = <25 IRQ_TYPE_EDGE_RISING>;
> >          };
> >      };
> >  ...
>