[PATCH 2/2 v2] [ARM] [IMX]: Fix clock use counter from underflow on multiple clk_disable().

[Vladimir Zapolskiy]

If clk_disable() is called for already disabled clock clk->usecount
value is decremented anyway. This leads to a problem that sequent
clk_enable() call doesn't enable the clock as expected.

Signed-off-by: Vladimir Zapolskiy <vzapolskiy at gmail.com>
Cc: Sascha Hauer <s.hauer at pengutronix.de>
Cc: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
---
 arch/arm/plat-mxc/clock.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c
index 2daec3c..3189275 100644
--- a/arch/arm/plat-mxc/clock.c
+++ b/arch/arm/plat-mxc/clock.c
@@ -53,10 +53,14 @@ static void __clk_disable(struct clk *clk)
 	if (clk == NULL || IS_ERR(clk))
 		return;
 
+	if (!clk->usecount) {
+		WARN(1, "Trying to disable a clock with 0 usecount\n");
+		return;
+	}
+
 	__clk_disable(clk->parent);
 	__clk_disable(clk->secondary);
 
-	WARN_ON(!clk->usecount);
 	if (!(--clk->usecount) && clk->disable)
 		clk->disable(clk);
 }
-- 
1.6.6.1