Hello Russell,
On Mon, 23 Feb 2009, Russell King - ARM Linux wrote:
> On Thu, Feb 19, 2009 at 06:50:52PM -0600, Woodruff, Richard wrote:
> > 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.
>
> It sounds to me like clk_set_parent() needs this then to prevent enabled
> clocks being reparented. By doing so, we no longer need to disable/enable
> the clock within the OMAP2/3 set_parent function since we are now
> guaranteed that the clock will be disabled.
>
> Ack?
One suggestion on the patch:
> diff --git a/arch/arm/plat-omap/clock.c b/arch/arm/plat-omap/clock.c
> index 08baa18..b2d9e1f 100644
> --- a/arch/arm/plat-omap/clock.c
> +++ b/arch/arm/plat-omap/clock.c
> @@ -144,12 +144,14 @@ 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);
> + }
> }
> spin_unlock_irqrestore(&clockfw_lock, flags);
Suggest returning a more specific error than -EINVAL:
if (clk->usecount > 0)
return -EBUSY;
- Paul
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