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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: Kalle Jokiniemi <kalle.jokiniemi@digia.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>
This commit is contained in:
Kalle Jokiniemi 2009-10-14 16:40:37 -06:00 committed by paul
parent 161291396e
commit a0219fbdac
1 changed files with 44 additions and 30 deletions
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74
arch/arm/mach-omap2/clockdomain.c
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@ -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);