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

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Date:   Fri, 23 Dec 2022 18:19:24 +0100
From:   Pavel Machek <pavel@....cz>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Chuanhong Guo <gch981213@...il.com>, linux-leds@...r.kernel.org,
        Lee Jones <lee@...nel.org>, 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

Hi!

> > 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?

This really needs to mention the name this hardware is known as -- I
believe it is NeoPixel.

Best regards,
								Pavel
-- 
People of Russia, stop Putin before his war on Ukraine escalates.

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