[PATCH 2/3] i2c: uniphier-f: avoid WARN_ON() of clk_disable() in failure path

From: Masahiro Yamada
Date: Thu Sep 01 2016 - 07:45:41 EST


If clk_prepare_enable() fails, clk_disable_unprepare() is called in
the failure path, where the enable_count is still zero, so it hits
WARN_ON(core->enable_count == 0) in the clk_core_disable().

To fix this, make the clock setting more linear in the probe function
so that it can exploit "goto err" in case of error.

Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---

drivers/i2c/busses/i2c-uniphier-f.c | 73 ++++++++++++++++---------------------
1 file changed, 32 insertions(+), 41 deletions(-)

diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c
index 3560853..2886685 100644
--- a/drivers/i2c/busses/i2c-uniphier-f.c
+++ b/drivers/i2c/busses/i2c-uniphier-f.c
@@ -455,41 +455,10 @@ static struct i2c_bus_recovery_info uniphier_fi2c_bus_recovery_info = {
.unprepare_recovery = uniphier_fi2c_unprepare_recovery,
};

-static int uniphier_fi2c_clk_init(struct device *dev,
- struct uniphier_fi2c_priv *priv)
+static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv,
+ u32 bus_speed, unsigned long clk_rate)
{
- struct device_node *np = dev->of_node;
- unsigned long clk_rate;
- u32 bus_speed, clk_count;
- int ret;
-
- if (of_property_read_u32(np, "clock-frequency", &bus_speed))
- bus_speed = UNIPHIER_FI2C_DEFAULT_SPEED;
-
- if (!bus_speed) {
- dev_err(dev, "clock-frequency should not be zero\n");
- return -EINVAL;
- }
-
- if (bus_speed > UNIPHIER_FI2C_MAX_SPEED)
- bus_speed = UNIPHIER_FI2C_MAX_SPEED;
-
- /* Get input clk rate through clk driver */
- priv->clk = devm_clk_get(dev, NULL);
- if (IS_ERR(priv->clk)) {
- dev_err(dev, "failed to get clock\n");
- return PTR_ERR(priv->clk);
- }
-
- ret = clk_prepare_enable(priv->clk);
- if (ret)
- return ret;
-
- clk_rate = clk_get_rate(priv->clk);
- if (!clk_rate) {
- dev_err(dev, "input clock rate should not be zero\n");
- return -EINVAL;
- }
+ u32 clk_count;

uniphier_fi2c_reset(priv);

@@ -501,8 +470,6 @@ static int uniphier_fi2c_clk_init(struct device *dev,
writel(clk_count / 16, priv->membase + UNIPHIER_FI2C_DSUT);

uniphier_fi2c_prepare_operation(priv);
-
- return 0;
}

static int uniphier_fi2c_probe(struct platform_device *pdev)
@@ -510,8 +477,9 @@ static int uniphier_fi2c_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct uniphier_fi2c_priv *priv;
struct resource *regs;
- int irq;
- int ret;
+ u32 bus_speed;
+ unsigned long clk_rate;
+ int irq, ret;

priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
@@ -528,6 +496,31 @@ static int uniphier_fi2c_probe(struct platform_device *pdev)
return irq;
}

+ if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
+ bus_speed = UNIPHIER_FI2C_DEFAULT_SPEED;
+
+ if (!bus_speed || bus_speed > UNIPHIER_FI2C_MAX_SPEED) {
+ dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
+ return -EINVAL;
+ }
+
+ priv->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk)) {
+ dev_err(dev, "failed to get clock\n");
+ return PTR_ERR(priv->clk);
+ }
+
+ ret = clk_prepare_enable(priv->clk);
+ if (ret)
+ return ret;
+
+ clk_rate = clk_get_rate(priv->clk);
+ if (!clk_rate) {
+ dev_err(dev, "input clock rate should not be zero\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
init_completion(&priv->comp);
priv->adap.owner = THIS_MODULE;
priv->adap.algo = &uniphier_fi2c_algo;
@@ -538,9 +531,7 @@ static int uniphier_fi2c_probe(struct platform_device *pdev)
i2c_set_adapdata(&priv->adap, priv);
platform_set_drvdata(pdev, priv);

- ret = uniphier_fi2c_clk_init(dev, priv);
- if (ret)
- goto err;
+ uniphier_fi2c_hw_init(priv, bus_speed, clk_rate);

ret = devm_request_irq(dev, irq, uniphier_fi2c_interrupt, 0,
pdev->name, priv);
--
1.9.1