On 11/12/2012 10:09 PM, Julius Werner wrote: > Thanks for moving this along, Daniel. I think this is the right > approach... the cpuidle driver shouldn't be more complex than > necessary. > > Note that you are starting your loop too high in cpuidle_play_dead... > states[state_count] is not an actual state anymore, it should start at > state_count - 1.
Yep. Thanks for catching this. > Also, I think you can go ahead and do the same > last-to-first loop transformation with immediate return in the menu > governor, for an extra tiny bit of performance. Yes, that makes sense. Thanks for the review. -- Daniel > On Mon, Nov 12, 2012 at 12:26 PM, Daniel Lezcano > <daniel.lezc...@linaro.org> wrote: >> This patch follows the discussion about reinitializing the power usage >> when a C-state is added/removed. >> >> https://lkml.org/lkml/2012/10/16/518 >> >> We realized the power usage field is never filled and when it is >> filled for tegra, the power_specified flag is not set making all these >> values to be resetted when the driver is initialized with the set_power_state >> function. >> >> Julius and I feel this is over-engineered and the power_specified >> flag could be simply removed and continue assuming the states are >> backward sorted. >> >> The menu governor select function is simplified as the power is ordered. >> Actually the condition is always true with the current code. >> >> The cpuidle_play_dead function is also simplified by doing a reverse lookup >> on the array. >> >> The set_power_states function is removed as it does no make sense anymore. >> >> Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org> >> --- >> drivers/cpuidle/cpuidle.c | 17 ++++------------- >> drivers/cpuidle/driver.c | 25 ------------------------- >> drivers/cpuidle/governors/menu.c | 8 ++------ >> include/linux/cpuidle.h | 2 +- >> 4 files changed, 7 insertions(+), 45 deletions(-) >> >> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c >> index 711dd83..f983262 100644 >> --- a/drivers/cpuidle/cpuidle.c >> +++ b/drivers/cpuidle/cpuidle.c >> @@ -69,24 +69,15 @@ int cpuidle_play_dead(void) >> { >> struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices); >> struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); >> - int i, dead_state = -1; >> - int power_usage = -1; >> + int i; >> >> if (!drv) >> return -ENODEV; >> >> /* Find lowest-power state that supports long-term idle */ >> - for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { >> - struct cpuidle_state *s = &drv->states[i]; >> - >> - if (s->power_usage < power_usage && s->enter_dead) { >> - power_usage = s->power_usage; >> - dead_state = i; >> - } >> - } >> - >> - if (dead_state != -1) >> - return drv->states[dead_state].enter_dead(dev, dead_state); >> + for (i = drv->state_count; i >= CPUIDLE_DRIVER_STATE_START; i--) >> + if (drv->states[i].play_dead) >> + return drv->states[i].enter_dead(dev, i); >> >> return -ENODEV; >> } >> diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c >> index 3af841f..bb045f1 100644 >> --- a/drivers/cpuidle/driver.c >> +++ b/drivers/cpuidle/driver.c >> @@ -19,34 +19,9 @@ DEFINE_SPINLOCK(cpuidle_driver_lock); >> static void __cpuidle_set_cpu_driver(struct cpuidle_driver *drv, int cpu); >> static struct cpuidle_driver * __cpuidle_get_cpu_driver(int cpu); >> >> -static void set_power_states(struct cpuidle_driver *drv) >> -{ >> - int i; >> - >> - /* >> - * cpuidle driver should set the drv->power_specified bit >> - * before registering if the driver provides >> - * power_usage numbers. >> - * >> - * If power_specified is not set, >> - * we fill in power_usage with decreasing values as the >> - * cpuidle code has an implicit assumption that state Cn >> - * uses less power than C(n-1). >> - * >> - * With CONFIG_ARCH_HAS_CPU_RELAX, C0 is already assigned >> - * an power value of -1. So we use -2, -3, etc, for other >> - * c-states. >> - */ >> - for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) >> - drv->states[i].power_usage = -1 - i; >> -} >> - >> static void __cpuidle_driver_init(struct cpuidle_driver *drv) >> { >> drv->refcnt = 0; >> - >> - if (!drv->power_specified) >> - set_power_states(drv); >> } >> >> static int __cpuidle_register_driver(struct cpuidle_driver *drv, int cpu) >> diff --git a/drivers/cpuidle/governors/menu.c >> b/drivers/cpuidle/governors/menu.c >> index 2efee27..14eb11f 100644 >> --- a/drivers/cpuidle/governors/menu.c >> +++ b/drivers/cpuidle/governors/menu.c >> @@ -312,7 +312,6 @@ static int menu_select(struct cpuidle_driver *drv, >> struct cpuidle_device *dev) >> { >> struct menu_device *data = &__get_cpu_var(menu_devices); >> int latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY); >> - int power_usage = -1; >> int i; >> int multiplier; >> struct timespec t; >> @@ -383,11 +382,8 @@ static int menu_select(struct cpuidle_driver *drv, >> struct cpuidle_device *dev) >> if (s->exit_latency * multiplier > data->predicted_us) >> continue; >> >> - if (s->power_usage < power_usage) { >> - power_usage = s->power_usage; >> - data->last_state_idx = i; >> - data->exit_us = s->exit_latency; >> - } >> + data->last_state_idx = i; >> + data->exit_us = s->exit_latency; >> } >> >> /* not deepest C-state chosen for low predicted residency */ >> diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h >> index 3711b34..24cd103 100644 >> --- a/include/linux/cpuidle.h >> +++ b/include/linux/cpuidle.h >> @@ -126,9 +126,9 @@ struct cpuidle_driver { >> struct module *owner; >> int refcnt; >> >> - unsigned int power_specified:1; >> /* set to 1 to use the core cpuidle time keeping (for all states). */ >> unsigned int en_core_tk_irqen:1; >> + /* states array must be ordered in decreasing power consumption */ >> struct cpuidle_state states[CPUIDLE_STATE_MAX]; >> int state_count; >> int safe_state_index; >> -- >> 1.7.5.4 >> -- <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | <http://twitter.com/#!/linaroorg> Twitter | <http://www.linaro.org/linaro-blog/> Blog _______________________________________________ linaro-dev mailing list linaro-dev@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-dev
