linux-kernel - Re: [PATH v2 2/2] spi: Add Qualcomm QUP SPI controller support

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Date:	Thu, 20 Feb 2014 00:28:49 +0900
From:	Mark Brown <broonie@...nel.org>
To:	"Ivan T. Ivanov" <iivanov@...sol.com>
Cc:	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>, linux-spi@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org, Alok Chauhan <alokc@...eaurora.org>,
	Gilad Avidov <gavidov@...eaurora.org>,
	Kiran Gunda <kgunda@...eaurora.org>,
	Sagar Dharia <sdharia@...eaurora.org>, dsneddon@...eaurora.org
Subject: Re: [PATH v2 2/2] spi: Add Qualcomm QUP SPI controller support

On Thu, Feb 13, 2014 at 06:21:38PM +0200, Ivan T. Ivanov wrote:

> Qualcomm Universal Peripheral (QUP) core is an AHB slave that
> provides a common data path (an output FIFO and an input FIFO)
> for serial peripheral interface (SPI) mini-core. SPI in master
> mode supports up to 50MHz, up to four chip selects, programmable
> data path from 4 bits to 32 bits and numerous protocol variants.

I've applied this since it mostly looks good but there's a few small
outstanding issues, please submit incremental patches fixing them.

> +#define SPI_CONFIG			0x0300
> +#define SPI_IO_CONTROL			0x0304
> +#define SPI_ERROR_FLAGS			0x0308
> +#define SPI_ERROR_FLAGS_EN		0x030c

You've got lots of defines that are just plain SPI_ which is looking for
namespace collisions - please prefix them.

> +	if (spi->chip_select >= spi->master->num_chipselect) {
> +		dev_err(controller->dev, "invalid chip_select %d\n",
> +			spi->chip_select);
> +		return -EINVAL;
> +	}

The core does this prior to allowing the slave to be registered at all.

> +
> +	if (spi->max_speed_hz > controller->max_speed_hz) {
> +		dev_err(controller->dev, "invalid max_speed_hz %d\n",
> +			spi->max_speed_hz);
> +		return -EINVAL;
> +	}

The core will check this for you if you set master->max_speed_hz.

> +#ifdef CONFIG_PM_RUNTIME
> +static int spi_qup_pm_suspend_runtime(struct device *device)
> +{
> +	struct spi_master *master = dev_get_drvdata(device);
> +	struct spi_qup *controller = spi_master_get_devdata(master);
> +	u32 config;
> +
> +	/* Enable clocks auto gaiting */
> +	config = readl(controller->base + QUP_CONFIG);
> +	config |= QUP_CLOCK_AUTO_GATE;
> +	writel_relaxed(config, controller->base + QUP_CONFIG);
> +	return 0;
> +}

Why not just enable this all the time?  I'd have expected some clock API
calls here similar to those in the main suspend and resume paths.

> +MODULE_VERSION("0.4");

Don't bother doing this, nobody will ever keep updating the version
number - the kernel version should be enough.

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