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

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Message-ID: <20200829174845.7fae971d@archlinux>
Date:   Sat, 29 Aug 2020 17:48:45 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Nishant Malpani <nish.malpani25@...il.com>
Cc:     robh+dt@...nel.org, dragos.bogdan@...log.com,
        darius.berghe@...log.com, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: iio: gyro: adxrs290: Add required
 interrupts property

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

> ---
>  .../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.

>  
>  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>;
>          };
>      };
>  ...