linux-kernel - Re: [PATCH v3 1/2] SPI: Add driver for Cadence SPI controller

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Message-ID: <20140410224825.GI6518@sirena.org.uk>
Date:	Thu, 10 Apr 2014 23:48:25 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Harini Katakam <harinik@...inx.com>
Cc:	grant.likely@...aro.org, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-doc@...r.kernel.org, michals@...inx.com
Subject: Re: [PATCH v3 1/2] SPI: Add driver for Cadence SPI controller

On Thu, Apr 10, 2014 at 05:43:49PM +0530, Harini Katakam wrote:
> Add driver for Cadence SPI controller. This is used in Xilinx Zynq.

This looks mostly good, the issues below are very small.

> +static int __maybe_unused cdns_spi_suspend(struct device *dev)
> +{
> +	struct platform_device *pdev = container_of(dev,
> +			struct platform_device, dev);
> +	struct spi_master *master = platform_get_drvdata(pdev);
> +	struct cdns_spi *xspi = spi_master_get_devdata(master);
> +
> +	spi_master_suspend(master);
> +
> +	clk_disable(xspi->ref_clk);
> +
> +	clk_disable(xspi->pclk);

You're only doing clk_disable() here, I would expect the clocks to also
be unprepared over suspend - there is no value in leaving them prepared
that I can see.  Just use clk_unprepare_disable().

It would also be good (though not essential) to implement runtime PM and
disable the clocks while there are no transfers in progress for a small
power saving.  The auto_runtime_pm feature in the core will do the
runtime PM calls for you.

Otherwise this looks good.

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