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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: Mikko Perttunen <mperttunen@nvidia.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Mikko Perttunen 2014-09-05 12:28:18 +03:00 committed by Wolfram Sang
parent 9e82bf0141
commit c9a9ef4170
1 changed files with 45 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
drivers/i2c/busses/i2c-tegra.c
View File

@ -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;
}