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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2009-02-24 12:46:31 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2009-03-03 13:08:18 +0000
commit4da3782151300237db3abe070f716922889252e0 (patch)
tree5bfc719384ffecf88ad93b286afe3008f24d281c /arch/arm/plat-omap
parent7aec53acc0504ab2abd73a6051e7b72f48545ceb (diff)
[ARM] omap: clk_set_parent: deny changing parent if clock is enabled
Richard Woodruff writes: | The historic usage of this has been against single use leaf clocks | (1st instance of gptimer). When it was used it did: | clk_get() | clk_set_parent() | clk_enable() | | This usage was ok for that. Use on a disabled clock is needed. | | If there are multiple users on the clock or it is enabled there are | problems. | | The call can still be unfriendly if 2 different drivers are using the | clock with their own clock get/enable. It might be the function should | return an error if usecount != 0 to stop surprises. It is all around | better if the parenting is done when the clock is off. This is a good reason to ensure that the clock is not enabled when clk_set_parent() is called. Acked-by: Richard Woodruff <r-woodruff2@ti.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/plat-omap')
-rw-r--r--arch/arm/plat-omap/clock.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c
index 08baa18497b..2e0614552ac 100644
--- a/arch/arm/plat-omap/clock.c
+++ b/arch/arm/plat-omap/clock.c
@@ -144,13 +144,16 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
return ret;
spin_lock_irqsave(&clockfw_lock, flags);
- if (arch_clock->clk_set_parent)
- ret = arch_clock->clk_set_parent(clk, parent);
- if (ret == 0) {
- if (clk->recalc)
- clk->rate = clk->recalc(clk);
- propagate_rate(clk);
- }
+ if (clk->usecount == 0) {
+ if (arch_clock->clk_set_parent)
+ ret = arch_clock->clk_set_parent(clk, parent);
+ if (ret == 0) {
+ if (clk->recalc)
+ clk->rate = clk->recalc(clk);
+ propagate_rate(clk);
+ }
+ } else
+ ret = -EBUSY;
spin_unlock_irqrestore(&clockfw_lock, flags);
return ret;