From: Mikko Perttunen <mperttunen@xxxxxxxxxx> 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: Mikko Perttunen <mperttunen@xxxxxxxxxx> --- v2: move set_rate before prepare drivers/i2c/busses/i2c-tegra.c | 57 +++++++++++++++++++++++++++++++++--------- 1 file changed, 45 insertions(+), 12 deletions(-) diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c index 87d0371..efba1eb 100644 --- a/drivers/i2c/busses/i2c-tegra.c +++ b/drivers/i2c/busses/i2c-tegra.c @@ -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; } -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
