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Commit d043d87c authored by Mike Turquette's avatar Mike Turquette Committed by Paul Walmsley
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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: default avatarMike Turquette <mturquette@ti.com>
[paul@pwsan.com: split the hwmod and clock disable cases; modified the
 code to skip the clockdomain handling during the disable-unused-clocks phase;
 added COMMON_CLK ifdef; removed include of clk-private.h at Mike's request]
Signed-off-by: default avatarPaul Walmsley <paul@pwsan.com>
parent b797be1d

arch/arm/mach-omap2/clockdomain.c

+56 −37
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include <linux/clk.h>

#include <linux/limits.h>

#include <linux/err.h>

#include <linux/clk-provider.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 +990,41 @@ 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;



	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);



#ifdef CONFIG_COMMON_CLK

	/* corner case: disabling unused clocks */

	if (__clk_get_enable_count(clk) == 0)

		goto ccd_exit;

#endif



	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);



#ifdef CONFIG_COMMON_CLK

ccd_exit:

#endif

	spin_unlock_irqrestore(&clkdm->lock, flags);



	return 0;

}



/**
@@ -1077,6 +1075,8 @@ 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 +1086,28 @@ 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;

}