linux-kernel - Re: [PATCH] spi: omap2-mcspi: Add support for GPIO chipselects

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Message-ID: <20150409105202.GU6023@sirena.org.uk>
Date:	Thu, 9 Apr 2015 11:52:02 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Michael Welling <mwelling@...e.org>
Cc:	linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: omap2-mcspi: Add support for GPIO chipselects

On Wed, Apr 08, 2015 at 04:36:01PM -0500, Michael Welling wrote:
> This patch allows for GPIOs specified in the devicetree to be used as SPI chipselects
> on TI OMAP2 SoCs.

Please keep your commit messages under 80 columns.

> +	if (gpio_is_valid(spi->cs_gpio)) {
> +		if (gpio_request(spi->cs_gpio, dev_name(&spi->dev)) == 0)
> +			gpio_direction_output(spi->cs_gpio,
> +					!(spi->mode & SPI_CS_HIGH));
> +	}

For this to work we need to be sure that unspecified GPIOs are invalid
which isn't normally the default - zero tends to be a valid GPIO and
that's also the default for otherwise uninitialized data.  Is there
something that takes care of this?

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