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 11:47:05 +0200
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     Boerge Struempfel <boerge.struempfel@...il.com>
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
Subject: Re: [PATCH v6 2/5] spi: spi-imx: add support for SPI_MOSI_IDLE_LOW
 mode bit

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.

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.

[1] https://github.com/fschrempf/py-neopixel-spidev
[2] https://github.com/doceme/py-spidev

Reviewed-by: Frieder Schrempf <frieder.schrempf@...tron.de>