Re: [RFC PATCH v2 1/2] dt-bindings: leds: Add multicolor PWM LED bindings

[Marek Behún <marek.behun@xxxxxx>]

On Tue, 25 Jan 2022 16:12:25 +0100
sven@xxxxxxxxxxxxxxxx wrote:

> From: Sven Schwermer <sven.schwermer@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> 
> This allows to group multiple PWM-connected monochrome LEDs into
> multicolor LEDs, e.g. RGB LEDs.
> 
> Signed-off-by: Sven Schwermer <sven.schwermer@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> ---
>  .../bindings/leds/leds-pwm-multicolor.yaml    | 76 +++++++++++++++++++
>  1 file changed, 76 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> new file mode 100644
> index 000000000000..b82b26f2e140
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/leds-pwm-multicolor.yaml
> @@ -0,0 +1,76 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/leds-pwm-multicolor.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Multi-color LEDs connected to PWM
> +
> +maintainers:
> +  - Sven Schwermer <sven.schwermer@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
> +
> +description: |
> +  This driver combines several monochrome PWM LEDs into one multi-color
> +  LED using the multicolor LED class.
> +
> +properties:
> +  compatible:
> +    const: pwm-leds-multicolor
> +
> +patternProperties:
> +  '^multi-led@[0-9a-f]$':
> +    type: object
> +    allOf:
> +      - $ref: leds-class-multicolor.yaml#
> +
> +    patternProperties:
> +      "^led-[0-9a-z]+$":
> +        type: object
> +        properties:
> +          pwms:
> +            maxItems: 1
> +
> +          pwm-names: true
> +
> +          color:
> +            $ref: common.yaml#/properties/color
> +
> +        required:
> +          - pwms
> +          - color
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/leds/common.h>
> +
> +    rgb-led {
> +        compatible = "pwm-leds-multicolor";
> +
> +        multi-led@0 {
> +          color = <LED_COLOR_ID_RGB>;
> +          function = LED_FUNCTION_INDICATOR;
> +          max-brightness = <65535>;
> +
> +          led-red {
> +              pwms = <&pwm1 0 1000000>;
> +              color = <LED_COLOR_ID_RED>;
> +          };
> +
> +          led-green {
> +              pwms = <&pwm2 0 1000000>;
> +              color = <LED_COLOR_ID_GREEN>;
> +          };
> +
> +          led-blue {
> +              pwms = <&pwm3 0 1000000>;
> +              color = <LED_COLOR_ID_BLUE>;
> +          };
> +        };

what about

	multi-led@0 {
		color = <LED_COLOR_ID_RGB>;
		function = LED_FUNCTION_INDICATOR;
		pwms = <&pwm1 0 1000000>,
		       <&pwm2 0 1000000>,
		       <&pwm3 0 1000000>;
		channels = <LED_COLOR_ID_RED>,
			   <LED_COLOR_ID_GREEN>,
			   <LED_COLOR_ID_BLUE>;
	};

I am not saying that it is necessarily better, just comenting that
maybe it is, since it saves some space. `pwms` is phandle-array, so it
can contain references to multiple pwms, and we have functions which
make getting these pwms in driver code easy...

Also this example won't compile with
   make dt_bindings_check
because you don't have pwm1, pwm2
and pwm3 defined...

Marek