linux-kernel - Re: [PATCH v6 2/5] spi: spi-imx: add support for SPI_MOSI_IDLE

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Date:   Wed, 24 May 2023 13:42:04 +0200
From:   Börge Strümpfel <boerge.struempfel@...il.com>
To:     Frieder Schrempf <frieder.schrempf@...tron.de>
Cc:     bstruempfel@...ratronik.de, andy.shevchenko@...il.com,
        festevam@...il.com, amit.kumar-mahapatra@....com,
        broonie@...nel.org, Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        linux-spi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, gch981213@...il.com
Subject: Re: [PATCH v6 2/5] spi: spi-imx: add support for SPI_MOSI_IDLE_LOW
 mode bit

Am Mi., 24. Mai 2023 um 11:47 Uhr schrieb Frieder Schrempf
<frieder.schrempf@...tron.de>:
>
> On 24.05.23 11:19, Boerge Struempfel wrote:
> > By default, the spi-imx controller pulls the mosi line high, whenever it
> > is idle. This behaviour can be inverted per CS by setting the
> > corresponding DATA_CTL bit in the config register of the controller.
> >
> > Also, since the controller mode-bits have to be touched anyways, the
> > SPI_CPOL and SPI_CPHA are replaced by the combined SPI_MODE_X_MASK flag.
> >
> > Signed-off-by: Boerge Struempfel <boerge.struempfel@...il.com>
>
> Thanks for working on this! We used a similar downstream patch for
> driving NeoPixels with i.MX. I'm happy to see a proper upstream solution.
>

Thanks for your reply. I'm glad to see that there is an interest for this
and I'm not the only one, who is working with this.

> I also have this Python module [1] around for using spidev to drive the
> LEDs. It would be nice to see support for SPI_MOSI_IDLE_LOW in py-spidev
> [2] so we could use it there. Though the latter looks a bit like it is
> not properly maintained anymore.

The python modules looks interesting.

FYI: there is already another patch by Chuanhong Guo on the mailing
list, which implements a proper driver for neopixel leds. It also allows
to add them via DT and access them via sys-fs. It might be an
interesting upstream alternative for your python module if it gets
accepted.

https://lore.kernel.org/lkml/20221212045558.69602-1-gch981213@gmail.com/

>
> [1] https://github.com/fschrempf/py-neopixel-spidev
> [2] https://github.com/doceme/py-spidev
>
> Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>

--
Kind Regards,
Börge Strümpfel