linux-kernel - Re: [PATCH v3 0/3] leds: add driver for SPI driven WorldSemi WS2812B RGB LEDs

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Date:   Tue, 13 Dec 2022 17:51:53 +0800
From:   Chuanhong Guo <gch981213@...il.com>
To:     Pavel Machek <pavel@....cz>
Cc:     linux-leds@...r.kernel.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 v3 0/3] leds: add driver for SPI driven WorldSemi WS2812B
 RGB LEDs

Hi!

On Tue, Dec 13, 2022 at 5:03 PM Pavel Machek <pavel@....cz> wrote:
>
> Hi!
>
> > This patch adds support for driving a chain of WS2812B LED chips
> > using SPI bus.
> >
> > WorldSemi WS2812B is a individually addressable LED chip that
> > can be chained together and controlled individually using a
> > single wire. The chip recognize a long pulse as a bit of 1 and
> > a short pulse as a bit of 0. Host sends a continuous stream
> > of 24-bits color values, each LED chip takes the first 3 byte
> > it receives as its color value and passes the leftover bytes to
> > the next LED on the chain.
> >
> > This driver simulates this protocol using SPI bus by sending
> > a long pulse as 3'b110 and a short pulse as 3'b100. The SPI
> > frequency needs to be 2.105MHz~2.85MHz for the timing to be
> > correct and the controller needs to transfer all the bytes
> > continuously.
>
> Is this the same thing as NeoPixel? If so, that may be better-known
> name.

NeoPixel is the name used by Adafruit for WS2812B based LED
strips. Even though that name may be better-known, this driver
is for the WS2812B LED chips, not for the specific Adafruit
products made using those chips. So I think it's more appropriate
to go with worldsemi,ws2812b instead of NeoPixel for the driver
name.

-- 
Regards,
Chuanhong Guo