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Message-ID: <08bd485b-51f6-8249-63a7-a6864a431276@linaro.org>
Date: Wed, 30 Nov 2022 09:33:08 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Sebastian Reichel <sre@...nel.org>
Cc: Chuanhong Guo <gch981213@...il.com>, 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
On 30/11/2022 01:14, Sebastian Reichel wrote:
>>> + 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
>>
>> Drop minItems.... but:
>>
>>> + maxItems: 3
>>> + items:
>>> + minimum: 0
>>> + maximum: 255
>>
>> default: 255
>
> I would argue, that the default should be 0 (off) instead of 255
> (full power).
Yes.
>
>> What controls the intensity? Don't you have PWM there?
>
> WS2812 is a RGB led, which contains a small Microcontroller. The µC
> takes 24 byte intensity data from a serial input and then passes on
> any following bits to the next LED. SPI clk and chip-select are
> ignored (chip-select support can be trivially added though).
>
> You can find them everywhere nowadays, since they are quite cheap
> (a few cents per LED) and need only one MOSI pin to control hundreds
> of LEDs.
OK. This should be anyway existing property, so default-brightness.
Best regards,
Krzysztof
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