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Diffstat (limited to 'drivers/cpuidle/cpuidle.c')
-rw-r--r--drivers/cpuidle/cpuidle.c49
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