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Message-ID: <1408096034-17270-1-git-send-email-mperttunen@nvidia.com>
Date: Fri, 15 Aug 2014 12:47:14 +0300
From: Mikko Perttunen <mperttunen@...dia.com>
To: <ldewangan@...dia.com>, <wsa@...-dreams.de>,
<swarren@...dotorg.org>, <thierry.reding@...il.com>
CC: <pdeschrijver@...dia.com>, <linux-i2c@...r.kernel.org>,
<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
Mikko Perttunen <mperttunen@...dia.com>
Subject: [PATCH] i2c: 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@...dia.com>
---
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..251f172 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;
+ }
+ }
+
+ 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;
+ }
+
+ 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_div_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;
}
--
1.8.1.5
--
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