diff options
| author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2009-02-24 12:46:31 +0000 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2009-03-03 13:08:18 +0000 |
| commit | 4da3782151300237db3abe070f716922889252e0 (patch) | |
| tree | 5bfc719384ffecf88ad93b286afe3008f24d281c /arch/arm | |
| parent | 7aec53acc0504ab2abd73a6051e7b72f48545ceb (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')
| -rw-r--r-- | arch/arm/mach-omap2/clock.c | 6 | ||||
| -rw-r--r-- | 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 40cb65ba1fa..f49bce997a0 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 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; |