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

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Date:   Wed, 30 Nov 2022 17:25:46 +0800
From:   Chuanhong Guo <gch981213@...il.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     linux-leds@...r.kernel.org, Pavel Machek <pavel@....cz>,
        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 2/3] dt-bindings: leds: add dt schema for worldsemi,ws2812b-spi

Hi!

On Wed, Nov 30, 2022 at 5:08 PM Krzysztof Kozlowski
<krzysztof.kozlowski@...aro.org> wrote:
> And that's exactly what I said - the compatibles should not include bus
> information. The bus information comes from... the bus!

Oh. I thought there will be a conflict if there is a SPI driver and
, say, an I2C driver with the same compatible string.

> [...]
> >>
> >> Why unit address is optional?
> >
> > It isn't. I copy-pasted it from led-class-multicolor.yaml and
> > didn't check the exact regex.
> > I'll fix it in the next version.
>
> Make it required and matching your case.

Got it.

> [...]
> >>> +      default-intensity:
> >>> +        description: |
> >>> +          An array of 3 integer specifying the default intensity of each color
> >>> +          components in this LED. <255 255 255> if unspecified.
> >>> +        $ref: /schemas/types.yaml#/definitions/uint32-array
> >>> +        minItems: 3
> [...]
> So this is brightness of each color...

I don't think so.
See the kernel doc for multicolor LED:
https://docs.kernel.org/leds/leds-class-multicolor.html
This property sets the sysfs file multi_intensity while the
actual LED brightness is controlled with another sysfs
file called 'brightness'.
Setting multi_intensity alone doesn't change the LED
brightness at all.

-- 
Regards,
Chuanhong Guo