Quoting Paul Walmsley (2012-11-09 11:08:00) > On Fri, 9 Nov 2012, Paul Walmsley wrote: > > > On Thu, 8 Nov 2012, Mike Turquette wrote: > > > > > You're right. In my rush I glossed over the clkdm decrement part. In > > > light of the suspend/resume issues I'm not sure this approach is really > > > valid. I think getting to the bottom of those issues will give the > > > final word. > > > > What do you think about something like this? It's still under test and > > review here, but seems to avoid the warnings on 3530ES3 Beagle at least. > > > > The usage of __clk_get_enable_count() in this code still seems like a hack > > to me. It would be better for the CCF to call a different clk_hw_ops > > function pointer for the disable-unused-clocks case. But if you agree, > > and plan to fix this, or have some other cleaner fix in mind for the near > > future, then something like this seems reasonable for the short term to > > me. What do you think? > For avoiding the WARNs, this seems fine to me. And I agree that a new clk_ops function pointer is needed. Maybe something like, void (*unused_disable)(struct clk_hw *hw); But I'm OK with the below patch in the short term. I just have one question: did you observe any PM regressions by skipping the clkdm programming? Thanks, Mike > Here's the patch. The changes to clkdm_clk_disable() are the important > ones, the rest can be ignored for the purposes of this review. > > > - Paul > > From: Mike Turquette <mturquette@xxxxxx> > Date: Fri, 9 Nov 2012 11:28:42 -0700 > Subject: [PATCH] ARM: OMAP2+: clockdomain: bypass clockdomain handling when > disabling unused clks > > The OMAP port to the common clk framework[1] resulted in spurious WARNs > while disable unused clocks. This is due to _clkdm_clk_hwmod_disable > catching clkdm->usecount's with a value of zero. Even less desirable it > would not allow the clkdm_clk_disable function pointer to get called due > to an early return of -ERANGE. > > This patch adds a check for such a corner case by skipping the WARN and > early return in the event that clkdm->usecount and clk->enable_usecount > are both zero. Presumably this could only happen during the check for > unused clocks at boot-time. > > [1] http://article.gmane.org/gmane.linux.ports.arm.omap/88824 > > Signed-off-by: Mike Turquette <mturquette@xxxxxx> > [paul@xxxxxxxxx: split the hwmod and clock disable cases; modified the > code to skip the clockdomain handling during the disable-unused-clocks phase] > --- > arch/arm/mach-omap2/clockdomain.c | 91 ++++++++++++++++++++++--------------- > 1 file changed, 54 insertions(+), 37 deletions(-) > > diff --git a/arch/arm/mach-omap2/clockdomain.c b/arch/arm/mach-omap2/clockdomain.c > index 64e5046..1bd0ff0 100644 > --- a/arch/arm/mach-omap2/clockdomain.c > +++ b/arch/arm/mach-omap2/clockdomain.c > @@ -22,6 +22,7 @@ > #include <linux/clk.h> > #include <linux/limits.h> > #include <linux/err.h> > +#include <linux/clk-private.h> > > #include <linux/io.h> > > @@ -947,35 +948,6 @@ static int _clkdm_clk_hwmod_enable(struct clockdomain *clkdm) > return 0; > } > > -static int _clkdm_clk_hwmod_disable(struct clockdomain *clkdm) > -{ > - unsigned long flags; > - > - if (!clkdm || !arch_clkdm || !arch_clkdm->clkdm_clk_disable) > - return -EINVAL; > - > - spin_lock_irqsave(&clkdm->lock, flags); > - > - if (atomic_read(&clkdm->usecount) == 0) { > - spin_unlock_irqrestore(&clkdm->lock, flags); > - WARN_ON(1); /* underflow */ > - return -ERANGE; > - } > - > - if (atomic_dec_return(&clkdm->usecount) > 0) { > - spin_unlock_irqrestore(&clkdm->lock, flags); > - return 0; > - } > - > - arch_clkdm->clkdm_clk_disable(clkdm); > - pwrdm_state_switch(clkdm->pwrdm.ptr); > - spin_unlock_irqrestore(&clkdm->lock, flags); > - > - pr_debug("clockdomain: %s: disabled\n", clkdm->name); > - > - return 0; > -} > - > /** > * clkdm_clk_enable - add an enabled downstream clock to this clkdm > * @clkdm: struct clockdomain * > @@ -1018,15 +990,39 @@ int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) > */ > int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk) > { > - /* > - * XXX Rewrite this code to maintain a list of enabled > - * downstream clocks for debugging purposes? > - */ > + unsigned long flags; > + int force_disable = 0; > > - if (!clk) > + if (!clkdm || !clk || !arch_clkdm || !arch_clkdm->clkdm_clk_disable) > return -EINVAL; > > - return _clkdm_clk_hwmod_disable(clkdm); > + spin_lock_irqsave(&clkdm->lock, flags); > + > + /* corner case: disabling unused clocks */ > + force_disable = (__clk_get_enable_count(clk) == 0) ? 1 : 0; > + if (force_disable) > + goto ccd_exit; > + > + if (atomic_read(&clkdm->usecount) == 0) { > + spin_unlock_irqrestore(&clkdm->lock, flags); > + WARN_ON(1); /* underflow */ > + return -ERANGE; > + } > + > + if (atomic_dec_return(&clkdm->usecount) > 0) { > + spin_unlock_irqrestore(&clkdm->lock, flags); > + return 0; > + } > + > + arch_clkdm->clkdm_clk_disable(clkdm); > + pwrdm_state_switch(clkdm->pwrdm.ptr); > + > + pr_debug("clockdomain: %s: disabled\n", clkdm->name); > + > +ccd_exit: > + spin_unlock_irqrestore(&clkdm->lock, flags); > + > + return 0; > } > > /** > @@ -1077,6 +1073,8 @@ int clkdm_hwmod_enable(struct clockdomain *clkdm, struct omap_hwmod *oh) > */ > int clkdm_hwmod_disable(struct clockdomain *clkdm, struct omap_hwmod *oh) > { > + unsigned long flags; > + > /* The clkdm attribute does not exist yet prior OMAP4 */ > if (cpu_is_omap24xx() || cpu_is_omap34xx()) > return 0; > @@ -1086,9 +1084,28 @@ int clkdm_hwmod_disable(struct clockdomain *clkdm, struct omap_hwmod *oh) > * downstream hwmods for debugging purposes? > */ > > - if (!oh) > + if (!clkdm || !oh || !arch_clkdm || !arch_clkdm->clkdm_clk_disable) > return -EINVAL; > > - return _clkdm_clk_hwmod_disable(clkdm); > + spin_lock_irqsave(&clkdm->lock, flags); > + > + if (atomic_read(&clkdm->usecount) == 0) { > + spin_unlock_irqrestore(&clkdm->lock, flags); > + WARN_ON(1); /* underflow */ > + return -ERANGE; > + } > + > + if (atomic_dec_return(&clkdm->usecount) > 0) { > + spin_unlock_irqrestore(&clkdm->lock, flags); > + return 0; > + } > + > + arch_clkdm->clkdm_clk_disable(clkdm); > + pwrdm_state_switch(clkdm->pwrdm.ptr); > + spin_unlock_irqrestore(&clkdm->lock, flags); > + > + pr_debug("clockdomain: %s: disabled\n", clkdm->name); > + > + return 0; > } > > -- > 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
