linux-kernel - Re: [PATCH] spi: Add option to keep the MOSI line low, when it is idle.

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Message-ID: <CAOMZO5B_a-oauJFsO8aXwSxu-3_=YiYbsHi-B=2MykkJ08fNtA@mail.gmail.com>
Date:   Thu, 11 May 2023 17:29:23 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Boerge Struempfel <boerge.struempfel@...il.com>
Cc:     bstruempfel@...ratronik.de, Mark Brown <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,
        Schrempf Frieder <frieder.schrempf@...tron.de>
Subject: Re: [PATCH] spi: Add option to keep the MOSI line low, when it is idle.

Hi Boerge,

On Thu, May 11, 2023 at 10:58 AM Boerge Struempfel
<boerge.struempfel@...il.com> wrote:
>
> By default, the imx spi controller uses a high mosi line, whenever it is
> idle. This may not be desired in all use cases. For example neopixel
> leds can get confused and flicker due to misinterpreting the idle state.
> Therefore, we introduce a new spi-mode bit, with which the idle behaviour
> can be overwritten on a per device basis.
...
> +       if (of_property_read_bool(nc, "spi-mosi-idle-low"))
> +               spi->mode |= SPI_MOSI_IDLE_LOW;

Yes, this is useful.

As this is a new property,  please send a patch that adds it to:
Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml

Thanks