From: Jean Pihet <[email protected]> One of the main contributors of the low power code latency is the PER power domain. To optimize the high-performance and low-latency C1 state, prevent any PER state which is lower than the CORE state in C1.
Reported and suggested by Kevin Hilman. Reported-by: Kevin Hilman <[email protected]> Signed-off-by: Jean Pihet <[email protected]> --- arch/arm/mach-omap2/cpuidle34xx.c | 38 +++++++++++++++++++----------------- 1 files changed, 20 insertions(+), 18 deletions(-) diff --git a/arch/arm/mach-omap2/cpuidle34xx.c b/arch/arm/mach-omap2/cpuidle34xx.c index 5358664..353dd8d 100644 --- a/arch/arm/mach-omap2/cpuidle34xx.c +++ b/arch/arm/mach-omap2/cpuidle34xx.c @@ -247,19 +247,18 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev, int index) { int new_state_idx; - u32 core_next_state, per_next_state = 0, per_saved_state = 0, cam_state; + u32 core_next_state, per_next_state = 0, per_saved_state = 0; struct omap3_idle_statedata *cx; int ret; /* - * Prevent idle completely if CAM is active. + * Use only C1 if CAM is active. * CAM does not have wakeup capability in OMAP3. */ - cam_state = pwrdm_read_pwrst(cam_pd); - if (cam_state == PWRDM_POWER_ON) { + if (pwrdm_read_pwrst(cam_pd) == PWRDM_POWER_ON) new_state_idx = drv->safe_state_index; - goto select_state; - } + else + new_state_idx = next_valid_state(dev, drv, index); /* * FIXME: we currently manage device-specific idle states @@ -269,24 +268,28 @@ static int omap3_enter_idle_bm(struct cpuidle_device *dev, * its own code. */ - /* - * Prevent PER off if CORE is not in retention or off as this - * would disable PER wakeups completely. - */ - cx = cpuidle_get_statedata(&dev->states_usage[index]); + /* Program PER state */ + cx = cpuidle_get_statedata(&dev->states_usage[new_state_idx]); core_next_state = cx->core_state; per_next_state = per_saved_state = pwrdm_read_next_pwrst(per_pd); - if ((per_next_state == PWRDM_POWER_OFF) && - (core_next_state > PWRDM_POWER_RET)) - per_next_state = PWRDM_POWER_RET; + if (new_state_idx == 0) { + /* In C1 do not allow PER state lower than CORE state */ + if (per_next_state < core_next_state) + per_next_state = core_next_state; + } else { + /* + * Prevent PER OFF if CORE is not in RETention or OFF as this + * would disable PER wakeups completely. + */ + if ((per_next_state == PWRDM_POWER_OFF) && + (core_next_state > PWRDM_POWER_RET)) + per_next_state = PWRDM_POWER_RET; + } /* Are we changing PER target state? */ if (per_next_state != per_saved_state) pwrdm_set_next_pwrst(per_pd, per_next_state); - new_state_idx = next_valid_state(dev, drv, index); - -select_state: ret = omap3_enter_idle(dev, drv, new_state_idx); /* Restore original PER state if it was modified */ @@ -372,7 +375,6 @@ int __init omap3_idle_init(void) /* C1 . MPU WFI + Core active */ _fill_cstate(drv, 0, "MPU ON + CORE ON"); - (&drv->states[0])->enter = omap3_enter_idle; drv->safe_state_index = 0; cx = _fill_cstate_usage(dev, 0); cx->valid = 1; /* C1 is always valid */ -- 1.7.7.6 -- 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
