From: Russell King <rmk@xxxxxxxxxxxxxxxxxxxxxxx>
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@xxxxxx>
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
---
arch/arm/mach-omap2/clock.c | 6 ------
arch/arm/plat-omap/clock.c | 17 ++++++++++-------
2 files changed, 10 insertions(+), 13 deletions(-)
diff --git a/arch/arm/mach-omap2/clock.c b/arch/arm/mach-omap2/clock.c
index 40cb65b..f49bce9 100644
--- a/arch/arm/mach-omap2/clock.c
+++ b/arch/arm/mach-omap2/clock.c
@@ -807,9 +807,6 @@ int omap2_clk_set_parent(struct clk *clk, struct clk *new_parent)
if (!parent_div)
return -EINVAL;
- if (clk->usecount > 0)
- _omap2_clk_disable(clk);
-
/* Set new source value (previous dividers if any in effect) */
v = __raw_readl(clk->clksel_reg);
v &= ~clk->clksel_mask;
@@ -819,9 +816,6 @@ int omap2_clk_set_parent(struct clk *clk, struct clk *new_parent)
_omap2xxx_clk_commit(clk);
- if (clk->usecount > 0)
- _omap2_clk_enable(clk);
-
clk_reparent(clk, new_parent);
/* CLKSEL clocks follow their parents' rates, divided by a divisor */
diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c
index 08baa18..2e06145 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;
--
1.6.1.2
--
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