[PATCH 1/1] arm: mxc: utilise usecount field in clock operations
in [Kernel]
|
Prev: [004/139] fat: fix buffer overflow in vfat_create_shortname()
Next: [009/139] drm/radeon/kms: fix pal tv-out support on legacy IGP chips
From: Amit Kucheria on 22 Apr 2010 16:40 From: Amit Kucheria <amit.kucheria(a)canonical.com> This patch fixes the clock refcounting when reparenting is used. Sascha just pointed out a good explanation of refcounting here: http://www.spinics.net/lists/arm-kernel/msg85879.html Signed-off-by: Amit Kucheria <amit.kucheria(a)canonical.com> --- arch/arm/plat-mxc/clock.c | 34 ++++++++++++++++++++++------------ 1 files changed, 22 insertions(+), 12 deletions(-) diff --git a/arch/arm/plat-mxc/clock.c b/arch/arm/plat-mxc/clock.c index 323ff8c..14781cc 100644 --- a/arch/arm/plat-mxc/clock.c +++ b/arch/arm/plat-mxc/clock.c @@ -50,15 +50,16 @@ static DEFINE_MUTEX(clocks_mutex); static void __clk_disable(struct clk *clk) { - if (clk == NULL || IS_ERR(clk)) + WARN_ON(!clk->usecount); + if (clk == NULL || IS_ERR(clk) || !clk->usecount) 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 +162,25 @@ EXPORT_SYMBOL(clk_set_rate); int clk_set_parent(struct clk *clk, struct clk *parent) { int ret = -EINVAL; + struct clk *prev_parent = clk->parent; if (clk == NULL || IS_ERR(clk) || parent == NULL || IS_ERR(parent) || clk->set_parent == NULL) return ret; + if (clk->usecount != 0) + clk_enable(parent); + mutex_lock(&clocks_mutex); ret = clk->set_parent(clk, parent); if (ret == 0) clk->parent = parent; + mutex_unlock(&clocks_mutex); + if (clk->usecount != 0) + clk_disable(prev_parent); + return ret; } EXPORT_SYMBOL(clk_set_parent); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |