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@xxxxxxxxx>
Cc: Kevin Hilman <khilman@xxxxxx>
---
arch/arm/mach-omap2/cpuidle34xx.c | 35 ++++++++++++++++++++++-------------
1 file changed, 22 insertions(+), 13 deletions(-)
diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c
index 0067467..ad70220 100644
--- a/arch/arm/mach-omap2/cpuidle34xx.c
+++ b/arch/arm/mach-omap2/cpuidle34xx.c
@@ -39,9 +39,21 @@ struct omap3_idle_statedata {
u8 mpu_state;
u8 core_state;
u8 per_min_state;
+ u8 flags;
};
/*
+ * 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
* disable PER wakeups completely.
*/
@@ -51,6 +63,7 @@ static struct omap3_idle_statedata omap3_idle_data[] = {
.core_state = PWRDM_POWER_ON,
/* In C1 do not allow PER state lower than CORE state */
.per_min_state = PWRDM_POWER_ON,
+ .flags = OMAP_CPUIDLE_CX_NO_CLKDM_IDLE,
},
{
.mpu_state = PWRDM_POWER_ON,
@@ -91,27 +104,25 @@ static int __omap3_enter_idle(struct cpuidle_device *dev,
int index)
{
struct omap3_idle_statedata *cx = &omap3_idle_data[index];
- u32 mpu_state = cx->mpu_state, core_state = cx->core_state;
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())
goto return_sleep_time;
/* 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(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
* VFP context is saved.
*/
- if (mpu_state == PWRDM_POWER_OFF)
+ if (cx->mpu_state == PWRDM_POWER_OFF)
cpu_pm_enter();
/* Execute ARM wfi */
@@ -121,17 +132,15 @@ static int __omap3_enter_idle(struct cpuidle_device *dev,
* Call idle CPU PM enter notifier chain to restore
* 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();
/* 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(core_pd->pwrdm_clkdms[0]);
- }
return_sleep_time:
-
local_fiq_enable();
return index;
@@ -196,7 +205,7 @@ static int next_valid_state(struct cpuidle_device *dev,
* Start search from the next (lower) state.
*/
for (idx = index - 1; idx >= 0; idx--) {
- cx = &omap3_idle_data[idx];
+ cx = &omap3_idle_data[idx];
if ((cx->mpu_state >= mpu_deepest_state) &&
(cx->core_state >= core_deepest_state)) {
next_index = idx;
--
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