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Commit 9b839ec0 authored by Amit Kucheria's avatar Amit Kucheria Committed by Sascha Hauer
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arm: mxc: utilise usecount field in clock operations 

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: default avatarAmit Kucheria <amit.kucheria@canonical.com>
Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
parent c45dd814

arch/arm/plat-mxc/clock.c

+25 −12
Original line number Diff line number Diff line
@@ -52,13 +52,14 @@ static void __clk_disable(struct clk *clk) 
{

	if (clk == NULL || IS_ERR(clk))

		return;

	WARN_ON(!clk->usecount);



	if (!(--clk->usecount)) {

		if (clk->disable)

			clk->disable(clk);

		__clk_disable(clk->parent);

		__clk_disable(clk->secondary);



	WARN_ON(!clk->usecount);

	if (!(--clk->usecount) && clk->disable)

		clk->disable(clk);

	}

}



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;



	if (clk->usecount++ == 0) {

		__clk_enable(clk->parent);

		__clk_enable(clk->secondary);



	if (clk->usecount++ == 0 && clk->enable)

		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);