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Subject[PATCH v3 7/7] ARM: LPC32xx: clock.c: Fix mutex lock issues
Date
This patch fixes the mutex issue in clock.c, as done in Kevin Wells' original
driver update:

In some cases, the clock drivers could grab a mutex twice in an improper
context. This patch changes the mutex mechanism to a simple irq lock/unlock
mechanism and removes un-needed locks from some functions.

(See also git.lpclinux.com)

Signed-off-by: Roland Stigge <stigge@antcom.de>
Tested-by: Wolfram Sang <w.sang@pengutronix.de>

diff --git a/arch/arm/mach-lpc32xx/clock.c b/arch/arm/mach-lpc32xx/clock.c
index 0606a63..0e01bf4 100644
--- a/arch/arm/mach-lpc32xx/clock.c
+++ b/arch/arm/mach-lpc32xx/clock.c
@@ -98,9 +98,10 @@
#include "clock.h"
#include "common.h"

+static DEFINE_SPINLOCK(global_clkregs_lock);
+
static struct clk clk_armpll;
static struct clk clk_usbpll;
-static DEFINE_MUTEX(clkm_lock);

/*
* Post divider values for PLLs based on selected register value
@@ -892,16 +893,6 @@ static struct clk clk_lcd = {
.enable_mask = LPC32XX_CLKPWR_LCDCTRL_CLK_EN,
};

-static inline void clk_lock(void)
-{
- mutex_lock(&clkm_lock);
-}
-
-static inline void clk_unlock(void)
-{
- mutex_unlock(&clkm_lock);
-}
-
static void local_clk_disable(struct clk *clk)
{
/* Don't attempt to disable clock if it has no users */
@@ -946,10 +937,11 @@ static int local_clk_enable(struct clk *clk)
int clk_enable(struct clk *clk)
{
int ret;
+ unsigned long flags;

- clk_lock();
+ spin_lock_irqsave(&global_clkregs_lock, flags);
ret = local_clk_enable(clk);
- clk_unlock();
+ spin_unlock_irqrestore(&global_clkregs_lock, flags);

return ret;
}
@@ -960,9 +952,11 @@ EXPORT_SYMBOL(clk_enable);
*/
void clk_disable(struct clk *clk)
{
- clk_lock();
+ unsigned long flags;
+
+ spin_lock_irqsave(&global_clkregs_lock, flags);
local_clk_disable(clk);
- clk_unlock();
+ spin_unlock_irqrestore(&global_clkregs_lock, flags);
}
EXPORT_SYMBOL(clk_disable);

@@ -971,13 +965,7 @@ EXPORT_SYMBOL(clk_disable);
*/
unsigned long clk_get_rate(struct clk *clk)
{
- unsigned long rate;
-
- clk_lock();
- rate = clk->get_rate(clk);
- clk_unlock();
-
- return rate;
+ return clk->get_rate(clk);
}
EXPORT_SYMBOL(clk_get_rate);

@@ -993,11 +981,8 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
* the actual rate set as part of the peripheral dividers
* instead of high level clock control
*/
- if (clk->set_rate) {
- clk_lock();
+ if (clk->set_rate)
ret = clk->set_rate(clk, rate);
- clk_unlock();
- }

return ret;
}
@@ -1008,15 +993,11 @@ EXPORT_SYMBOL(clk_set_rate);
*/
long clk_round_rate(struct clk *clk, unsigned long rate)
{
- clk_lock();
-
if (clk->round_rate)
rate = clk->round_rate(clk, rate);
else
rate = clk->get_rate(clk);

- clk_unlock();
-
return rate;
}
EXPORT_SYMBOL(clk_round_rate);

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