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>

1 files changed, 15 insertions, 5 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index a7b9e679a2ef..af6dd599c464 100644
--- 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. */