linux-kernel - Re: [PATCH v4 2/3] dt-bindings: leds: add worldsemi,ws2812b

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Date:   Mon, 12 Dec 2022 09:56:46 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Chuanhong Guo <gch981213@...il.com>, linux-leds@...r.kernel.org,
        Pavel Machek <pavel@....cz>, Lee Jones <lee@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Stanislav Jakubek <stano.jakubek@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Johan Hovold <johan+linaro@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Sven Schwermer <sven.schwermer@...ruptive-technologies.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 2/3] dt-bindings: leds: add worldsemi,ws2812b

On 12/12/2022 05:55, Chuanhong Guo wrote:
> Add dt binding schema for WorldSemi WS2812B driven using SPI
> bus.
> 
> Signed-off-by: Chuanhong Guo <gch981213@...il.com>
> ---
> Changes since v1:
> remove linux driver reference from description
> remove some obvious descriptions
> fix unit address regex in multi-led property
> drop various minItems
> add maxItems = 1 to reg
> fix node names and property orders in binding example
> drop -spi from compatible string
> add default-brightness
> 
> Change since v2:
> drop "this patch" from commit message
> rename leds to led-controller
> drop default-brightness and default-intensity
> 
> Change since v3:
> reword commit title
> 
>  .../bindings/leds/worldsemi,ws2812b.yaml      | 116 ++++++++++++++++++
>  1 file changed, 116 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/worldsemi,ws2812b.yaml
> 
> diff --git a/Documentation/devicetree/bindings/leds/worldsemi,ws2812b.yaml b/Documentation/devicetree/bindings/leds/worldsemi,ws2812b.yaml
> new file mode 100644
> index 000000000000..548c05ac3d31
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/worldsemi,ws2812b.yaml
> @@ -0,0 +1,116 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/worldsemi,ws2812b.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: WS2812B LEDs driven using SPI
> +
> +maintainers:
> +  - Chuanhong Guo <gch981213@...il.com>
> +
> +description: |
> +  WorldSemi WS2812B is a individually addressable LED chip that can be chained
> +  together and controlled individually using a single wire.
> +  This binding describes a chain of WS2812B LEDs connected to the SPI MOSI pin.
> +  Typical setups includes connecting the data pin of the LED chain to MOSI as
> +  the only device or using CS and MOSI with a tri-state voltage-level shifter
> +  for the data pin.
> +  The SPI frequency needs to be 2.105MHz~2.85MHz for the timing to be correct
> +  and the controller needs to send all the bytes continuously.
> +
> +allOf:
> +  - $ref: /schemas/spi/spi-peripheral-props.yaml#
> +
> +properties:
> +  compatible:
> +    const: worldsemi,ws2812b
> +
> +  reg:
> +    maxItems: 1
> +
> +  spi-max-frequency:
> +    minimum: 2105000
> +    maximum: 2850000
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +patternProperties:
> +  "^multi-led@[0-9a-f]+$":
> +    type: object
> +    $ref: leds-class-multicolor.yaml#
> +    unevaluatedProperties: false
> +
> +    properties:
> +      color-index:
> +        description: |
> +          A 3-item array specifying color of each components in this LED. It
> +          should be one of the LED_COLOR_ID_* prefixed definitions from the
> +          header include/dt-bindings/leds/common.h. Defaults to
> +          <LED_COLOR_ID_GREEN LED_COLOR_ID_RED LED_COLOR_ID_BLUE>
> +          if unspecified.
> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> +        maxItems: 3

In general I am fine with it, although there is still question for
adding more multi-color defines in binding headers to replace this
property - GRB/RBG/GBR and even more for RGBW.

Pavel, Lee, any thoughts from your side?

Best regards,
Krzysztof