Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a0219fbd authored by Kalle Jokiniemi's avatar Kalle Jokiniemi Committed by paul
Browse files

OMAP: Fix race condition with autodeps 



There is a possible race condition in clockdomain
code handling hw supported idle transitions.

When multiple autodeps dependencies are being added
or removed, a transition of still remaining dependent
powerdomain can result in false readings of the
state counter. This is especially fatal for off mode
state counter, as it could result in a driver not
noticing a context loss.

Fixed by disabling hw supported state transitions
when autodeps are being changed.

Signed-off-by: default avatarKalle Jokiniemi <kalle.jokiniemi@digia.com>
Signed-off-by: default avatarPaul Walmsley <paul@pwsan.com>
parent 16129139

arch/arm/mach-omap2/clockdomain.c

+44 −30
Original line number Diff line number Diff line
@@ -137,6 +137,36 @@ static void _clkdm_del_autodeps(struct clockdomain *clkdm) 
	}

}



/*

 * _omap2_clkdm_set_hwsup - set the hwsup idle transition bit

 * @clkdm: struct clockdomain *

 * @enable: int 0 to disable, 1 to enable

 *

 * Internal helper for actually switching the bit that controls hwsup

 * idle transitions for clkdm.

 */

static void _omap2_clkdm_set_hwsup(struct clockdomain *clkdm, int enable)

{

	u32 v;



	if (cpu_is_omap24xx()) {

		if (enable)

			v = OMAP24XX_CLKSTCTRL_ENABLE_AUTO;

		else

			v = OMAP24XX_CLKSTCTRL_DISABLE_AUTO;

	} else if (cpu_is_omap34xx()) {

		if (enable)

			v = OMAP34XX_CLKSTCTRL_ENABLE_AUTO;

		else

			v = OMAP34XX_CLKSTCTRL_DISABLE_AUTO;

	} else {

		BUG();

	}



	cm_rmw_mod_reg_bits(clkdm->clktrctrl_mask,

			    v << __ffs(clkdm->clktrctrl_mask),

			    clkdm->pwrdm.ptr->prcm_offs, CM_CLKSTCTRL);

}



static struct clockdomain *_clkdm_lookup(const char *name)

{
@@ -456,8 +486,6 @@ int omap2_clkdm_wakeup(struct clockdomain *clkdm) 
 */

void omap2_clkdm_allow_idle(struct clockdomain *clkdm)

{

	u32 v;



	if (!clkdm)

		return;
@@ -473,18 +501,7 @@ void omap2_clkdm_allow_idle(struct clockdomain *clkdm) 
	if (atomic_read(&clkdm->usecount) > 0)

		_clkdm_add_autodeps(clkdm);



	if (cpu_is_omap24xx())

		v = OMAP24XX_CLKSTCTRL_ENABLE_AUTO;

	else if (cpu_is_omap34xx())

		v = OMAP34XX_CLKSTCTRL_ENABLE_AUTO;

	else

		BUG();





	cm_rmw_mod_reg_bits(clkdm->clktrctrl_mask,

			    v << __ffs(clkdm->clktrctrl_mask),

			    clkdm->pwrdm.ptr->prcm_offs,

			    CM_CLKSTCTRL);

	_omap2_clkdm_set_hwsup(clkdm, 1);



	pwrdm_clkdm_state_switch(clkdm);

}
@@ -500,8 +517,6 @@ void omap2_clkdm_allow_idle(struct clockdomain *clkdm) 
 */

void omap2_clkdm_deny_idle(struct clockdomain *clkdm)

{

	u32 v;



	if (!clkdm)

		return;
@@ -514,16 +529,7 @@ void omap2_clkdm_deny_idle(struct clockdomain *clkdm) 
	pr_debug("clockdomain: disabling automatic idle transitions for %s\n",

		 clkdm->name);



	if (cpu_is_omap24xx())

		v = OMAP24XX_CLKSTCTRL_DISABLE_AUTO;

	else if (cpu_is_omap34xx())

		v = OMAP34XX_CLKSTCTRL_DISABLE_AUTO;

	else

		BUG();



	cm_rmw_mod_reg_bits(clkdm->clktrctrl_mask,

			    v << __ffs(clkdm->clktrctrl_mask),

			    clkdm->pwrdm.ptr->prcm_offs, CM_CLKSTCTRL);

	_omap2_clkdm_set_hwsup(clkdm, 0);



	if (atomic_read(&clkdm->usecount) > 0)

		_clkdm_del_autodeps(clkdm);
@@ -569,10 +575,14 @@ int omap2_clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk) 
	v = omap2_clkdm_clktrctrl_read(clkdm);



	if ((cpu_is_omap34xx() && v == OMAP34XX_CLKSTCTRL_ENABLE_AUTO) ||

	    (cpu_is_omap24xx() && v == OMAP24XX_CLKSTCTRL_ENABLE_AUTO))

	    (cpu_is_omap24xx() && v == OMAP24XX_CLKSTCTRL_ENABLE_AUTO)) {

		/* Disable HW transitions when we are changing deps */

		_omap2_clkdm_set_hwsup(clkdm, 0);

		_clkdm_add_autodeps(clkdm);

	else

		_omap2_clkdm_set_hwsup(clkdm, 1);

	} else {

		omap2_clkdm_wakeup(clkdm);

	}



	pwrdm_wait_transition(clkdm->pwrdm.ptr);

	pwrdm_clkdm_state_switch(clkdm);
@@ -623,10 +633,14 @@ int omap2_clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk) 
	v = omap2_clkdm_clktrctrl_read(clkdm);



	if ((cpu_is_omap34xx() && v == OMAP34XX_CLKSTCTRL_ENABLE_AUTO) ||

	    (cpu_is_omap24xx() && v == OMAP24XX_CLKSTCTRL_ENABLE_AUTO))

	    (cpu_is_omap24xx() && v == OMAP24XX_CLKSTCTRL_ENABLE_AUTO)) {

		/* Disable HW transitions when we are changing deps */

		_omap2_clkdm_set_hwsup(clkdm, 0);

		_clkdm_del_autodeps(clkdm);

	else

		_omap2_clkdm_set_hwsup(clkdm, 1);

	} else {

		omap2_clkdm_sleep(clkdm);

	}



	pwrdm_clkdm_state_switch(clkdm);