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arm: mxc: utilise usecount field in clock operations

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This patch fixes the clock refcounting when reparenting is used.

Boot-tested on imx51 babbage board.

Sascha pointed out a good explanation of refcounting here:
http://www.spinics.net/lists/arm-kernel/msg85879.html

Signed-off-by: Amit Kucheria <amit.kucheria@canonical.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Amit Kucheria 2010-05-28 11:29:09 +03:00 committed by Sascha Hauer
parent c45dd81400
commit 9b839ec0a8
1 changed files with 25 additions and 12 deletions
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37
arch/arm/plat-mxc/clock.c
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@ -52,13 +52,14 @@ static void __clk_disable(struct clk *clk)
{
if (clk == NULL || IS_ERR(clk))
return;
__clk_disable(clk->parent);
__clk_disable(clk->secondary);
WARN_ON(!clk->usecount);
if (!(--clk->usecount) && clk->disable)
clk->disable(clk);
if (!(--clk->usecount)) {
if (clk->disable)
clk->disable(clk);
__clk_disable(clk->parent);
__clk_disable(clk->secondary);
}
}
static int __clk_enable(struct clk *clk)
@ -66,12 +67,13 @@ static int __clk_enable(struct clk *clk)
if (clk == NULL || IS_ERR(clk))
return -EINVAL;
__clk_enable(clk->parent);
__clk_enable(clk->secondary);
if (clk->usecount++ == 0 && clk->enable)
clk->enable(clk);
if (clk->usecount++ == 0) {
__clk_enable(clk->parent);
__clk_enable(clk->secondary);
if (clk->enable)
clk->enable(clk);
}
return 0;
}
@ -160,17 +162,28 @@ EXPORT_SYMBOL(clk_set_rate);
int clk_set_parent(struct clk *clk, struct clk *parent)
{
int ret = -EINVAL;
struct clk *old;
if (clk == NULL || IS_ERR(clk) || parent == NULL ||
IS_ERR(parent) || clk->set_parent == NULL)
return ret;
if (clk->usecount)
clk_enable(parent);
mutex_lock(&clocks_mutex);
ret = clk->set_parent(clk, parent);
if (ret == 0)
if (ret == 0) {
old = clk->parent;
clk->parent = parent;
} else {
old = parent;
}
mutex_unlock(&clocks_mutex);
if (clk->usecount)
clk_disable(old);
return ret;
}
EXPORT_SYMBOL(clk_set_parent);