[PATCH 4/8] OMAP2+: PM: idle clkdms only if already in idle
Rajendra Nayak
rnayak at ti.com
Fri Jun 10 07:22:18 EDT 2011
On 6/10/2011 5:45 AM, Todd Poynor wrote:
>> + int hwsup = 0;
>> >
>> > if (pwrdm == NULL || IS_ERR(pwrdm))
>> > return -EINVAL;
>> > @@ -127,6 +128,7 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm, u32 state)
>> > (pwrdm->flags& PWRDM_HAS_LOWPOWERSTATECHANGE)) {
>> > sleep_switch = LOWPOWERSTATE_SWITCH;
>> > } else {
>> > + hwsup = clkdm_is_idle(pwrdm->pwrdm_clkdms[0]);
>> > clkdm_wakeup(pwrdm->pwrdm_clkdms[0]);
>> > pwrdm_wait_transition(pwrdm);
>> > sleep_switch = FORCEWAKEUP_SWITCH;
>> > @@ -142,7 +144,7 @@ int omap_set_pwrdm_state(struct powerdomain *pwrdm, u32 state)
>> >
>> > switch (sleep_switch) {
>> > case FORCEWAKEUP_SWITCH:
>> > - if (pwrdm->pwrdm_clkdms[0]->flags& CLKDM_CAN_ENABLE_AUTO)
>> > + if (hwsup)
>> > clkdm_allow_idle(pwrdm->pwrdm_clkdms[0]);
>> > else
>> > clkdm_sleep(pwrdm->pwrdm_clkdms[0]);
> Is concurrency protection needed here? Not sure if it's expected that
> multiple threads would simultaneously manage the state of the same power
> domain, or that the associated clock domain would change state
> concurrently.
Yeah, maybe there is a need for a per-clkdm lock to prevent these
concurrency issues. This race between omap_set_pwrdm_state and
clk_enable/disable all programming clkdm state was one possibility
for a race (even without this series), but with this series to move the
clkdm handling into hwmod there are certainly more possibilities (across
concurrent omap_hwmod_enable/idle) because the hwmod framework uses
per-hwmod lock while the clock framework used a global lock.
Thanks for bringing this up.
Paul/Benoit any thoughts on if a per-clkdm lock seems reasonable?
I just did a quick patch to add per-clkdm locking, it also has a
couple instances of arch-specific clkdm calls making
calls back to generic clkdm framework fixed, which
otherwise would result in recursive locking.
----
From: Rajendra Nayak <rnayak at ti.com>
Date: Fri, 10 Jun 2011 15:42:25 +0530
Subject: [PATCH] OMAP: clockdomain: Add per clkdm lock to prevent
concurrent state programming
Since the clkdm state programming is now done from
within the hwmod framework (which uses a per-hwmod
lock) instead of the being done from the clock
framework (which used a global lock), there is
now a need to have per-clkdm locking to prevent
races between different hwmods/modules belonging to the
same clock domain concurrently programming the
clkdm state.
Signed-off-by: Rajendra Nayak <rnayak at ti.com>
---
arch/arm/mach-omap2/clockdomain.c | 42
++++++++++++++++++++++++++--
arch/arm/mach-omap2/clockdomain.h | 2 +
arch/arm/mach-omap2/clockdomain2xxx_3xxx.c | 6 ++-
arch/arm/mach-omap2/clockdomain44xx.c | 7 ++--
4 files changed, 49 insertions(+), 8 deletions(-)
diff --git a/arch/arm/mach-omap2/clockdomain.c
b/arch/arm/mach-omap2/clockdomain.c
index b98a972..374e669 100644
--- a/arch/arm/mach-omap2/clockdomain.c
+++ b/arch/arm/mach-omap2/clockdomain.c
@@ -92,6 +92,8 @@ static int _clkdm_register(struct clockdomain *clkdm)
pwrdm_add_clkdm(pwrdm, clkdm);
+ spin_lock_init(&clkdm->lock);
+
pr_debug("clockdomain: registered %s\n", clkdm->name);
return 0;
@@ -690,6 +692,9 @@ int clkdm_clear_all_sleepdeps(struct clockdomain *clkdm)
*/
int clkdm_sleep(struct clockdomain *clkdm)
{
+ int ret;
+ unsigned long flags;
+
if (!clkdm)
return -EINVAL;
@@ -704,7 +709,10 @@ int clkdm_sleep(struct clockdomain *clkdm)
pr_debug("clockdomain: forcing sleep on %s\n", clkdm->name);
- return arch_clkdm->clkdm_sleep(clkdm);
+ spin_lock_irqsave(&clkdm->lock, flags);
+ ret = arch_clkdm->clkdm_sleep(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
+ return ret;
}
/**
@@ -718,6 +726,9 @@ int clkdm_sleep(struct clockdomain *clkdm)
*/
int clkdm_wakeup(struct clockdomain *clkdm)
{
+ int ret;
+ unsigned long flags;
+
if (!clkdm)
return -EINVAL;
@@ -732,7 +743,10 @@ int clkdm_wakeup(struct clockdomain *clkdm)
pr_debug("clockdomain: forcing wakeup on %s\n", clkdm->name);
- return arch_clkdm->clkdm_wakeup(clkdm);
+ spin_lock_irqsave(&clkdm->lock, flags);
+ ret = arch_clkdm->clkdm_wakeup(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
+ return ret;
}
/**
@@ -747,6 +761,8 @@ int clkdm_wakeup(struct clockdomain *clkdm)
*/
void clkdm_allow_idle(struct clockdomain *clkdm)
{
+ unsigned long flags;
+
if (!clkdm)
return;
@@ -762,8 +778,10 @@ void clkdm_allow_idle(struct clockdomain *clkdm)
pr_debug("clockdomain: enabling automatic idle transitions for %s\n",
clkdm->name);
+ spin_lock_irqsave(&clkdm->lock, flags);
arch_clkdm->clkdm_allow_idle(clkdm);
pwrdm_clkdm_state_switch(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
}
/**
@@ -777,6 +795,8 @@ void clkdm_allow_idle(struct clockdomain *clkdm)
*/
void clkdm_deny_idle(struct clockdomain *clkdm)
{
+ unsigned long flags;
+
if (!clkdm)
return;
@@ -792,7 +812,9 @@ void clkdm_deny_idle(struct clockdomain *clkdm)
pr_debug("clockdomain: disabling automatic idle transitions for %s\n",
clkdm->name);
+ spin_lock_irqsave(&clkdm->lock, flags);
arch_clkdm->clkdm_deny_idle(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
}
/**
@@ -805,6 +827,9 @@ void clkdm_deny_idle(struct clockdomain *clkdm)
*/
int clkdm_is_idle(struct clockdomain *clkdm)
{
+ int ret;
+ unsigned long flags;
+
if (!clkdm)
return -EINVAL;
@@ -813,7 +838,10 @@ int clkdm_is_idle(struct clockdomain *clkdm)
pr_debug("clockdomain: reading idle state for %s\n", clkdm->name);
- return arch_clkdm->clkdm_is_idle(clkdm);
+ spin_lock_irqsave(&clkdm->lock, flags);
+ ret = arch_clkdm->clkdm_is_idle(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
+ return ret;
}
@@ -835,6 +863,8 @@ int clkdm_is_idle(struct clockdomain *clkdm)
*/
int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk)
{
+ unsigned long flags;
+
/*
* XXX Rewrite this code to maintain a list of enabled
* downstream clocks for debugging purposes?
@@ -859,9 +889,11 @@ int clkdm_clk_enable(struct clockdomain *clkdm,
struct clk *clk)
pr_debug("clockdomain: clkdm %s: clk %s now enabled\n", clkdm->name,
clk->name);
+ spin_lock_irqsave(&clkdm->lock, flags);
arch_clkdm->clkdm_clk_enable(clkdm);
pwrdm_wait_transition(clkdm->pwrdm.ptr);
pwrdm_clkdm_state_switch(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
return 0;
}
@@ -882,6 +914,8 @@ int clkdm_clk_enable(struct clockdomain *clkdm,
struct clk *clk)
*/
int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk)
{
+ unsigned long flags;
+
/*
* XXX Rewrite this code to maintain a list of enabled
* downstream clocks for debugging purposes?
@@ -908,8 +942,10 @@ int clkdm_clk_disable(struct clockdomain *clkdm,
struct clk *clk)
pr_debug("clockdomain: clkdm %s: clk %s now disabled\n", clkdm->name,
clk->name);
+ spin_lock_irqsave(&clkdm->lock, flags);
arch_clkdm->clkdm_clk_disable(clkdm);
pwrdm_clkdm_state_switch(clkdm);
+ spin_unlock_irqrestore(&clkdm->lock, flags);
return 0;
}
diff --git a/arch/arm/mach-omap2/clockdomain.h
b/arch/arm/mach-omap2/clockdomain.h
index 085ed82..9fd4eb5 100644
--- a/arch/arm/mach-omap2/clockdomain.h
+++ b/arch/arm/mach-omap2/clockdomain.h
@@ -17,6 +17,7 @@
#define __ARCH_ARM_MACH_OMAP2_CLOCKDOMAIN_H
#include <linux/init.h>
+#include <linux/spinlock.h>
#include "powerdomain.h"
#include <plat/clock.h>
@@ -122,6 +123,7 @@ struct clockdomain {
const struct omap_chip_id omap_chip;
atomic_t usecount;
struct list_head node;
+ spinlock_t lock;
};
/**
diff --git a/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c
b/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c
index e0c393f..f841ac8 100644
--- a/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c
+++ b/arch/arm/mach-omap2/clockdomain2xxx_3xxx.c
@@ -193,7 +193,8 @@ static int omap2_clkdm_clk_enable(struct clockdomain
*clkdm)
_clkdm_add_autodeps(clkdm);
_enable_hwsup(clkdm);
} else {
- clkdm_wakeup(clkdm);
+ if (clkdm->flags & CLKDM_CAN_FORCE_WAKEUP)
+ omap2_clkdm_wakeup(clkdm);
}
return 0;
@@ -215,7 +216,8 @@ static int omap2_clkdm_clk_disable(struct
clockdomain *clkdm)
_clkdm_del_autodeps(clkdm);
_enable_hwsup(clkdm);
} else {
- clkdm_sleep(clkdm);
+ if (clkdm->flags & CLKDM_CAN_FORCE_SLEEP)
+ omap2_clkdm_sleep(clkdm);
}
return 0;
diff --git a/arch/arm/mach-omap2/clockdomain44xx.c
b/arch/arm/mach-omap2/clockdomain44xx.c
index e4b8e06..911770b 100644
--- a/arch/arm/mach-omap2/clockdomain44xx.c
+++ b/arch/arm/mach-omap2/clockdomain44xx.c
@@ -101,7 +101,8 @@ static int omap4_clkdm_is_idle(struct clockdomain
*clkdm)
static int omap4_clkdm_clk_enable(struct clockdomain *clkdm)
{
- clkdm_wakeup(clkdm);
+ if (clkdm->flags & CLKDM_CAN_FORCE_WAKEUP)
+ return omap4_clkdm_wakeup(clkdm);
return 0;
}
@@ -112,8 +113,8 @@ static int omap4_clkdm_clk_disable(struct
clockdomain *clkdm)
hwsup = omap4_cminst_is_clkdm_in_hwsup(clkdm->prcm_partition,
clkdm->cm_inst, clkdm->clkdm_offs);
- if (!hwsup)
- clkdm_sleep(clkdm);
+ if (!hwsup && (clkdm->flags & CLKDM_CAN_FORCE_SLEEP))
+ omap4_clkdm_sleep(clkdm);
return 0;
}
--
1.7.0.4
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