Commit c9a9ef41 authored by Mikko Perttunen's avatar Mikko Perttunen Committed by Wolfram Sang
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i2c: tegra: Move clk_prepare/clk_set_rate to probe 

Currently the i2c-tegra bus driver prepares, enables
and set_rates its clocks separately for each transfer.
This causes locking problems when doing I2C transfers
from clock notifiers; see
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/268653.html



This patch moves clk_prepare/unprepare and clk_set_rate calls to
the probe function, leaving only clk_enable/disable to be
done on each transfer. This solves the locking issue.

Signed-off-by: default avatarMikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: default avatarStephen Warren <swarren@nvidia.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 9e82bf01

drivers/i2c/busses/i2c-tegra.c

+45 −12
Original line number Diff line number Diff line
@@ -380,34 +380,33 @@ static inline int tegra_i2c_clock_enable(struct tegra_i2c_dev *i2c_dev) 
{

	int ret;

	if (!i2c_dev->hw->has_single_clk_source) {

		ret = clk_prepare_enable(i2c_dev->fast_clk);

		ret = clk_enable(i2c_dev->fast_clk);

		if (ret < 0) {

			dev_err(i2c_dev->dev,

				"Enabling fast clk failed, err %d\n", ret);

			return ret;

		}

	}

	ret = clk_prepare_enable(i2c_dev->div_clk);

	ret = clk_enable(i2c_dev->div_clk);

	if (ret < 0) {

		dev_err(i2c_dev->dev,

			"Enabling div clk failed, err %d\n", ret);

		clk_disable_unprepare(i2c_dev->fast_clk);

		clk_disable(i2c_dev->fast_clk);

	}

	return ret;

}



static inline void tegra_i2c_clock_disable(struct tegra_i2c_dev *i2c_dev)

{

	clk_disable_unprepare(i2c_dev->div_clk);

	clk_disable(i2c_dev->div_clk);

	if (!i2c_dev->hw->has_single_clk_source)

		clk_disable_unprepare(i2c_dev->fast_clk);

		clk_disable(i2c_dev->fast_clk);

}



static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)

{

	u32 val;

	int err = 0;

	int clk_multiplier = I2C_CLK_MULTIPLIER_STD_FAST_MODE;

	u32 clk_divisor;



	err = tegra_i2c_clock_enable(i2c_dev);
@@ -428,9 +427,6 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev) 
	i2c_writel(i2c_dev, val, I2C_CNFG);

	i2c_writel(i2c_dev, 0, I2C_INT_MASK);



	clk_multiplier *= (i2c_dev->hw->clk_divisor_std_fast_mode + 1);

	clk_set_rate(i2c_dev->div_clk, i2c_dev->bus_clk_rate * clk_multiplier);



	/* Make sure clock divisor programmed correctly */

	clk_divisor = i2c_dev->hw->clk_divisor_hs_mode;

	clk_divisor |= i2c_dev->hw->clk_divisor_std_fast_mode <<
@@ -712,6 +708,7 @@ static int tegra_i2c_probe(struct platform_device *pdev) 
	void __iomem *base;

	int irq;

	int ret = 0;

	int clk_multiplier = I2C_CLK_MULTIPLIER_STD_FAST_MODE;



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	base = devm_ioremap_resource(&pdev->dev, res);
@@ -777,17 +774,39 @@ static int tegra_i2c_probe(struct platform_device *pdev) 


	platform_set_drvdata(pdev, i2c_dev);



	if (!i2c_dev->hw->has_single_clk_source) {

		ret = clk_prepare(i2c_dev->fast_clk);

		if (ret < 0) {

			dev_err(i2c_dev->dev, "Clock prepare failed %d\n", ret);

			return ret;

		}

	}



	clk_multiplier *= (i2c_dev->hw->clk_divisor_std_fast_mode + 1);

	ret = clk_set_rate(i2c_dev->div_clk,

			   i2c_dev->bus_clk_rate * clk_multiplier);

	if (ret) {

		dev_err(i2c_dev->dev, "Clock rate change failed %d\n", ret);

		goto unprepare_fast_clk;

	}



	ret = clk_prepare(i2c_dev->div_clk);

	if (ret < 0) {

		dev_err(i2c_dev->dev, "Clock prepare failed %d\n", ret);

		goto unprepare_fast_clk;

	}



	ret = tegra_i2c_init(i2c_dev);

	if (ret) {

		dev_err(&pdev->dev, "Failed to initialize i2c controller");

		return ret;

		goto unprepare_div_clk;

	}



	ret = devm_request_irq(&pdev->dev, i2c_dev->irq,

			tegra_i2c_isr, 0, dev_name(&pdev->dev), i2c_dev);

	if (ret) {

		dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);

		return ret;

		goto unprepare_div_clk;

	}



	i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
@@ -803,16 +822,30 @@ static int tegra_i2c_probe(struct platform_device *pdev) 
	ret = i2c_add_numbered_adapter(&i2c_dev->adapter);

	if (ret) {

		dev_err(&pdev->dev, "Failed to add I2C adapter\n");

		return ret;

		goto unprepare_div_clk;

	}



	return 0;



unprepare_div_clk:

	clk_unprepare(i2c_dev->div_clk);



unprepare_fast_clk:

	if (!i2c_dev->hw->has_single_clk_source)

		clk_unprepare(i2c_dev->fast_clk);



	return ret;

}



static int tegra_i2c_remove(struct platform_device *pdev)

{

	struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);

	i2c_del_adapter(&i2c_dev->adapter);



	clk_unprepare(i2c_dev->div_clk);

	if (!i2c_dev->hw->has_single_clk_source)

		clk_unprepare(i2c_dev->fast_clk);



	return 0;

}

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