diff options
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 49 |
1 files changed, 44 insertions, 5 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 23a8d6cc8d30..4d534582514e 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -20,6 +20,7 @@ #include <linux/hrtimer.h> #include <linux/module.h> #include <linux/suspend.h> +#include <linux/tick.h> #include <trace/events/power.h> #include "cpuidle.h" @@ -69,18 +70,20 @@ int cpuidle_play_dead(void) * cpuidle_find_deepest_state - Find deepest state meeting specific conditions. * @drv: cpuidle driver for the given CPU. * @dev: cpuidle device for the given CPU. + * @freeze: Whether or not the state should be suitable for suspend-to-idle. */ static int cpuidle_find_deepest_state(struct cpuidle_driver *drv, - struct cpuidle_device *dev) + struct cpuidle_device *dev, bool freeze) { unsigned int latency_req = 0; - int i, ret = CPUIDLE_DRIVER_STATE_START - 1; + int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1; for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) { struct cpuidle_state *s = &drv->states[i]; struct cpuidle_state_usage *su = &dev->states_usage[i]; - if (s->disabled || su->disable || s->exit_latency <= latency_req) + if (s->disabled || su->disable || s->exit_latency <= latency_req + || (freeze && !s->enter_freeze)) continue; latency_req = s->exit_latency; @@ -89,10 +92,31 @@ static int cpuidle_find_deepest_state(struct cpuidle_driver *drv, return ret; } +static void enter_freeze_proper(struct cpuidle_driver *drv, + struct cpuidle_device *dev, int index) +{ + tick_freeze(); + /* + * The state used here cannot be a "coupled" one, because the "coupled" + * cpuidle mechanism enables interrupts and doing that with timekeeping + * suspended is generally unsafe. + */ + drv->states[index].enter_freeze(dev, drv, index); + WARN_ON(!irqs_disabled()); + /* + * timekeeping_resume() that will be called by tick_unfreeze() for the + * last CPU executing it calls functions containing RCU read-side + * critical sections, so tell RCU about that. + */ + RCU_NONIDLE(tick_unfreeze()); +} + /** * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle. * - * Find the deepest state available and enter it. + * If there are states with the ->enter_freeze callback, find the deepest of + * them and enter it with frozen tick. Otherwise, find the deepest state + * available and enter it normally. */ void cpuidle_enter_freeze(void) { @@ -100,7 +124,22 @@ void cpuidle_enter_freeze(void) struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); int index; - index = cpuidle_find_deepest_state(drv, dev); + /* + * Find the deepest state with ->enter_freeze present, which guarantees + * that interrupts won't be enabled when it exits and allows the tick to + * be frozen safely. + */ + index = cpuidle_find_deepest_state(drv, dev, true); + if (index >= 0) { + enter_freeze_proper(drv, dev, index); + return; + } + + /* + * It is not safe to freeze the tick, find the deepest state available + * at all and try to enter it normally. + */ + index = cpuidle_find_deepest_state(drv, dev, false); if (index >= 0) cpuidle_enter(drv, dev, index); else |
