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

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Message-ID: <Y5jJbdlYe24MdWsi@amd.ucw.cz>
Date:   Tue, 13 Dec 2022 19:50:21 +0100
From:   Pavel Machek <pavel@....cz>
To:     Chuanhong Guo <gch981213@...il.com>
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!

> > > 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.

Still, it would be suitable to mention the "NeoPixel" name in the
comment at begining of driver, and in Kconfig text.

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

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