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ARM: OMAP3xxx: CPUIdle: optimize __omap3_enter_idle() 

Avoid programming the MPU and CORE powerdomain next-power-state
registers if those powerdomains will never enter low-power states
(e.g., the state that people refer to as "C1").

To avoid making assumptions about CPUIdle states based on their order
in the list, use a flag to mark CPUIdle states that don't enter
powerdomain low-power states.

Avoid a previous-power-state register read on the MPU powerdomain
unless we know that the MPU was supposed to go OFF during the last
state transition.  Previous-power-state register reads can be very
expensive, so it's worth avoiding these when possible.

Since the CORE_L3 clockdomain can't go inactive unless the MPU is active,
there's little point blocking autoidle on the CORE_L3 clockdomain in "C1"
state, since we've programmed the MPU clockdomain to stay active.
Remove the unnecessary code.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
This commit is contained in:
Paul Walmsley 2013-01-26 00:58:13 -07:00
parent fd6b42a561
commit 1cd96478cf
1 changed files with 22 additions and 13 deletions
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33
arch/arm/mach-omap2/cpuidle34xx.c
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@ -39,10 +39,22 @@ struct omap3_idle_statedata {
u8 mpu_state; u8 mpu_state;
u8 core_state; u8 core_state;
u8 per_min_state; u8 per_min_state;
u8 flags;
}; };
static struct powerdomain *mpu_pd, *core_pd, *per_pd, *cam_pd; static struct powerdomain *mpu_pd, *core_pd, *per_pd, *cam_pd;
/*
* Possible flag bits for struct omap3_idle_statedata.flags:
*
* OMAP_CPUIDLE_CX_NO_CLKDM_IDLE: don't allow the MPU clockdomain to go
* inactive. This in turn prevents the MPU DPLL from entering autoidle
* mode, so wakeup latency is greatly reduced, at the cost of additional
* energy consumption. This also prevents the CORE clockdomain from
* entering idle.
*/
#define OMAP_CPUIDLE_CX_NO_CLKDM_IDLE BIT(0)
/* /*
* Prevent PER OFF if CORE is not in RETention or OFF as this would * Prevent PER OFF if CORE is not in RETention or OFF as this would
* disable PER wakeups completely. * disable PER wakeups completely.
@ -53,6 +65,7 @@ static struct omap3_idle_statedata omap3_idle_data[] = {
.core_state = PWRDM_POWER_ON, .core_state = PWRDM_POWER_ON,
/* In C1 do not allow PER state lower than CORE state */ /* In C1 do not allow PER state lower than CORE state */
.per_min_state = PWRDM_POWER_ON, .per_min_state = PWRDM_POWER_ON,
.flags = OMAP_CPUIDLE_CX_NO_CLKDM_IDLE,
}, },
{ {
.mpu_state = PWRDM_POWER_ON, .mpu_state = PWRDM_POWER_ON,
@ -93,27 +106,25 @@ static int __omap3_enter_idle(struct cpuidle_device *dev,
int index) int index)
{ {
struct omap3_idle_statedata *cx = &omap3_idle_data[index]; struct omap3_idle_statedata *cx = &omap3_idle_data[index];
u32 mpu_state = cx->mpu_state, core_state = cx->core_state;
local_fiq_disable(); local_fiq_disable();
pwrdm_set_next_pwrst(mpu_pd, mpu_state);
pwrdm_set_next_pwrst(core_pd, core_state);
if (omap_irq_pending() || need_resched()) if (omap_irq_pending() || need_resched())
goto return_sleep_time; goto return_sleep_time;
/* Deny idle for C1 */ /* Deny idle for C1 */
if (index == 0) { if (cx->flags & OMAP_CPUIDLE_CX_NO_CLKDM_IDLE) {
clkdm_deny_idle(mpu_pd->pwrdm_clkdms[0]); clkdm_deny_idle(mpu_pd->pwrdm_clkdms[0]);
clkdm_deny_idle(core_pd->pwrdm_clkdms[0]); } else {
pwrdm_set_next_pwrst(mpu_pd, cx->mpu_state);
pwrdm_set_next_pwrst(core_pd, cx->core_state);
} }
/* /*
* Call idle CPU PM enter notifier chain so that * Call idle CPU PM enter notifier chain so that
* VFP context is saved. * VFP context is saved.
*/ */
if (mpu_state == PWRDM_POWER_OFF) if (cx->mpu_state == PWRDM_POWER_OFF)
cpu_pm_enter(); cpu_pm_enter();
/* Execute ARM wfi */ /* Execute ARM wfi */
@ -123,17 +134,15 @@ static int __omap3_enter_idle(struct cpuidle_device *dev,
* Call idle CPU PM enter notifier chain to restore * Call idle CPU PM enter notifier chain to restore
* VFP context. * VFP context.
*/ */
if (pwrdm_read_prev_pwrst(mpu_pd) == PWRDM_POWER_OFF) if (cx->mpu_state == PWRDM_POWER_OFF &&
pwrdm_read_prev_pwrst(mpu_pd) == PWRDM_POWER_OFF)
cpu_pm_exit(); cpu_pm_exit();
/* Re-allow idle for C1 */ /* Re-allow idle for C1 */
if (index == 0) { if (cx->flags & OMAP_CPUIDLE_CX_NO_CLKDM_IDLE)
clkdm_allow_idle(mpu_pd->pwrdm_clkdms[0]); clkdm_allow_idle(mpu_pd->pwrdm_clkdms[0]);
clkdm_allow_idle(core_pd->pwrdm_clkdms[0]);
}
return_sleep_time: return_sleep_time:
local_fiq_enable(); local_fiq_enable();
return index; return index;