cpuidle: Select a different state on tick_broadcast_enter() failures

If tick_broadcast_enter() fails in cpuidle_enter_state(),
try to find another idle state to enter instead of invoking
default_idle_call() immediately and returning -EBUSY which
should increase the chances of saving some energy in those
cases.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Tested-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Kevin Hilman <khilman@linaro.org>

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index a7b9e679a2efe19677ecb74d37884deb9d75c552..af6dd599c4649edf97e2821fc433374162fb3b28 100644 (file)
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -73,7 +73,10 @@ int cpuidle_play_dead(void)
 }
 
 static int find_deepest_state(struct cpuidle_driver *drv,
-                             struct cpuidle_device *dev, bool freeze)
+                             struct cpuidle_device *dev,
+                             unsigned int max_latency,
+                             unsigned int forbidden_flags,
+                             bool freeze)
 {
        unsigned int latency_req = 0;
        int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1;
@@ -83,6 +86,8 @@ static int find_deepest_state(struct cpuidle_driver *drv,
                struct cpuidle_state_usage *su = &dev->states_usage[i];
 
                if (s->disabled || su->disable || s->exit_latency <= latency_req
+                   || s->exit_latency > max_latency
+                   || (s->flags & forbidden_flags)
                    || (freeze && !s->enter_freeze))
                        continue;
 
@@ -100,7 +105,7 @@ static int find_deepest_state(struct cpuidle_driver *drv,
 int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
                               struct cpuidle_device *dev)
 {
-       return find_deepest_state(drv, dev, false);
+       return find_deepest_state(drv, dev, UINT_MAX, 0, false);
 }
 
 static void enter_freeze_proper(struct cpuidle_driver *drv,
@@ -139,7 +144,7 @@ int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
         * that interrupts won't be enabled when it exits and allows the tick to
         * be frozen safely.
         */
-       index = find_deepest_state(drv, dev, true);
+       index = find_deepest_state(drv, dev, UINT_MAX, 0, true);
        if (index >= 0)
                enter_freeze_proper(drv, dev, index);
 
@@ -168,8 +173,13 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
         * CPU as a broadcast timer, this call may fail if it is not available.
         */
        if (broadcast && tick_broadcast_enter()) {
-               default_idle_call();
-               return -EBUSY;
+               index = find_deepest_state(drv, dev, target_state->exit_latency,
+                                          CPUIDLE_FLAG_TIMER_STOP, false);
+               if (index < 0) {
+                       default_idle_call();
+                       return -EBUSY;
+               }
+               target_state = &drv->states[index];
        }
 
        /* Take note of the planned idle state. */