From: Russell King <[email protected]> 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 <[email protected]> Signed-off-by: Russell King <[email protected]> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
