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 <[email protected]> Cc: Kevin Hilman <[email protected]> --- 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; -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
