cpuidle / sleep: Use broadcast timer for states that stop local timer

Commit 381063133246 (PM / sleep: Re-implement suspend-to-idle handling)
overlooked the fact that entering some sufficiently deep idle states
by CPUs may cause their local timers to stop and in those cases it
is necessary to switch over to a broadcast timer prior to entering
the idle state.  If the cpuidle driver in use does not provide
the new ->enter_freeze callback for any of the idle states, that
problem affects suspend-to-idle too, but it is not taken into account
after the changes made by commit 381063133246.

Fix that by changing the definition of cpuidle_enter_freeze() and
re-arranging of the code in cpuidle_idle_call(), so the former does
not call cpuidle_enter() any more and the fallback case is handled
by cpuidle_idle_call() directly.

Fixes: 381063133246 (PM / sleep: Re-implement suspend-to-idle handling)
Reported-and-tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

1 files changed, 21 insertions, 9 deletions

diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index 84b93b68482a..80014a178342 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -82,6 +82,7 @@ static void cpuidle_idle_call(void)
         struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
         int next_state, entered_state;
         unsigned int broadcast;
+        bool reflect;
 
         /*
          * Check if the idle task must be rescheduled. If it is the
@@ -105,6 +106,9 @@ static void cpuidle_idle_call(void)
          */
         rcu_idle_enter();
 
+        if (cpuidle_not_available(drv, dev))
+                goto use_default;
+
         /*
          * Suspend-to-idle ("freeze") is a system state in which all user space
          * has been frozen, all I/O devices have been suspended and the only
@@ -115,15 +119,22 @@ static void cpuidle_idle_call(void)
          * until a proper wakeup interrupt happens.
          */
         if (idle_should_freeze()) {
-                cpuidle_enter_freeze();
-                goto exit_idle;
-        }
+                entered_state = cpuidle_enter_freeze(drv, dev);
+                if (entered_state >= 0) {
+                        local_irq_enable();
+                        goto exit_idle;
+                }
 
-        /*
-         * Ask the cpuidle framework to choose a convenient idle state.
-         * Fall back to the default arch idle method on errors.
-         */
-        next_state = cpuidle_select(drv, dev);
+                reflect = false;
+                next_state = cpuidle_find_deepest_state(drv, dev);
+        } else {
+                reflect = true;
+                /*
+                 * Ask the cpuidle framework to choose a convenient idle state.
+                 */
+                next_state = cpuidle_select(drv, dev);
+        }
+        /* Fall back to the default arch idle method on errors. */
         if (next_state < 0)
                 goto use_default;
 
@@ -170,7 +181,8 @@ static void cpuidle_idle_call(void)
         /*
          * Give the governor an opportunity to reflect on the outcome
          */
-        cpuidle_reflect(dev, entered_state);
+        if (reflect)
+                cpuidle_reflect(dev, entered_state);
 
 exit_idle:
         __current_set_polling();