Re: [PATCH 1/3] dt-bindings: counter: add gpio-quadrature-encoder binding

[Wadim Mueller]

On 2026-04-17 17:13, Conor Dooley wrote:

Thanks for the review

> On Thu, Apr 16, 2026 at 10:48:17PM +0200, Wadim Mueller wrote:
> > Add devicetree binding documentation for the GPIO-based quadrature
> > encoder counter driver. The driver reads A/B quadrature signals and
> > an optional index pulse via edge-triggered GPIO interrupts, supporting
> > X1, X2, X4 quadrature decoding and pulse-direction mode.
> > 
> > This is useful on SoCs that lack a dedicated hardware quadrature
> > decoder or where the encoder is wired to generic GPIO pins.
> > 
> > Signed-off-by: Wadim Mueller <wafgo01@xxxxxxxxx>
> > ---
> >  .../counter/gpio-quadrature-encoder.yaml      | 69 +++++++++++++++++++
> >  1 file changed, 69 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml
> > 
> > diff --git a/Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml b/Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml
> > new file mode 100644
> > index 000000000..a52deaab6
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml
> > @@ -0,0 +1,69 @@
> > +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/counter/gpio-quadrature-encoder.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: GPIO-based Quadrature Encoder
> > +
> > +maintainers:
> > +  - Wadim Mueller <wadim.mueller@xxxxxxxx>
> > +
> > +description: |
> > +  A generic GPIO-based quadrature encoder counter.  Reads A/B quadrature
> > +  signals and an optional index pulse via edge-triggered GPIO interrupts.
> > +  Supports X1, X2, X4 quadrature decoding and pulse-direction mode.
> > +
> 
> > +  This driver is useful on SoCs that lack a dedicated hardware quadrature
> > +  decoder (eQEP, QEI, etc.) or where the encoder is wired to generic GPIO
> > +  pins rather than to a dedicated peripheral.
> 
> Idea seems okay to me. Please rephrase this section to avoid talking
> about drivers...

Thanks, will fix that in v2.

> 
> > +
> > +properties:
> > +  compatible:
> > +    const: gpio-quadrature-encoder
> > +
> > +  encoder-a-gpios:
> > +    maxItems: 1
> > +    description:
> > +      GPIO connected to the encoder's A (phase A) output.
> > +
> > +  encoder-b-gpios:
> > +    maxItems: 1
> > +    description:
> > +      GPIO connected to the encoder's B (phase B) output.
> > +
> > +  encoder-index-gpios:
> > +    maxItems: 1
> > +    description:
> > +      Optional GPIO connected to the encoder's index (Z) output.
> > +      When the index input is enabled via sysfs, the count resets
> > +      to zero on each index pulse.
> 
> ...and this to stop talking about sysfs and driver behaviour though.
> Bindings are about hardware.
> pw-bot: changes-requested
> 

Agreed, will rephrase to mention hardware signals only

> > +
> > +required:
> > +  - compatible
> > +  - encoder-a-gpios
> > +  - encoder-b-gpios
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    quadrature-encoder-0 {
> > +        compatible = "gpio-quadrature-encoder";
> > +        encoder-a-gpios = <&gpio0 10 GPIO_ACTIVE_HIGH>;
> > +        encoder-b-gpios = <&gpio0 11 GPIO_ACTIVE_HIGH>;
> > +    };
> > +
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    quadrature-encoder-1 {
> > +        compatible = "gpio-quadrature-encoder";
> > +        encoder-a-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
> > +        encoder-b-gpios = <&gpio0 11 GPIO_ACTIVE_LOW>;
> > +        encoder-index-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
> > +    };
> 
> I think this example alone is sufficient btw.
> 

Ack, will drop the first example

> Cheers,
> Conor.
> > +
> > +...
> > -- 
> > 2.52.0
> >