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, 22 insertions, 40 deletions

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 8b3e132..080bd2d 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -44,8 +44,8 @@ void disable_cpuidle(void)
 	off = 1;
 }
 
-static bool cpuidle_not_available(struct cpuidle_driver *drv,
-				  struct cpuidle_device *dev)
+bool cpuidle_not_available(struct cpuidle_driver *drv,
+			   struct cpuidle_device *dev)
 {
 	return off || !initialized || !drv || !dev || !dev->enabled;
 }
@@ -72,14 +72,8 @@ int cpuidle_play_dead(void)
 	return -ENODEV;
 }
 
-/**
- * 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, bool freeze)
+static int find_deepest_state(struct cpuidle_driver *drv,
+			      struct cpuidle_device *dev, bool freeze)
 {
 	unsigned int latency_req = 0;
 	int i, ret = freeze ? -1 : CPUIDLE_DRIVER_STATE_START - 1;
@@ -98,6 +92,17 @@ static int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
 	return ret;
 }
 
+/**
+ * cpuidle_find_deepest_state - Find the deepest available idle state.
+ * @drv: cpuidle driver for the given CPU.
+ * @dev: cpuidle device for the given CPU.
+ */
+int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
+			       struct cpuidle_device *dev)
+{
+	return find_deepest_state(drv, dev, false);
+}
+
 static void enter_freeze_proper(struct cpuidle_driver *drv,
 				struct cpuidle_device *dev, int index)
 {
@@ -119,46 +124,26 @@ static void enter_freeze_proper(struct cpuidle_driver *drv,
 
 /**
  * cpuidle_enter_freeze - Enter an idle state suitable for suspend-to-idle.
+ * @drv: cpuidle driver for the given CPU.
+ * @dev: cpuidle device for the given CPU.
  *
  * 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.
- *
- * Returns with enabled interrupts.
+ * them and enter it with frozen tick.
  */
-void cpuidle_enter_freeze(void)
+int cpuidle_enter_freeze(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 {
-	struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
-	struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
 	int index;
 
-	if (cpuidle_not_available(drv, dev))
-		goto fallback;
-
 	/*
 	 * 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) {
+	index = find_deepest_state(drv, dev, true);
+	if (index >= 0)
 		enter_freeze_proper(drv, dev, index);
-		local_irq_enable();
-		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);
-		return;
-	}
-
- fallback:
-	arch_cpu_idle();
+	return index;
 }
 
 /**
@@ -217,9 +202,6 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
  */
 int cpuidle_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 {
-	if (cpuidle_not_available(drv, dev))
-		return -ENODEV;
-
 	return cpuidle_curr_governor->select(drv, dev);
 }