If the CPU isn't able to go in states where the clock event will
be stopped we can ignore CLOCK_EVT_FEAT_C3STOP flag.

Signed-off-by: Benjamin Gaignard <benjamin.gaign...@st.com>
---
 kernel/time/tick-broadcast.c |  6 +++---
 kernel/time/tick-common.c    |  4 ++--
 kernel/time/tick-internal.h  | 12 ++++++++++++
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index e51778c312f1..5393778d7703 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -78,7 +78,7 @@ static bool tick_check_broadcast_device(struct 
clock_event_device *curdev,
 {
        if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) ||
            (newdev->features & CLOCK_EVT_FEAT_PERCPU) ||
-           (newdev->features & CLOCK_EVT_FEAT_C3STOP))
+           tick_broadcast_could_stop(newdev))
                return false;
 
        if (tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT &&
@@ -188,7 +188,7 @@ int tick_device_uses_broadcast(struct clock_event_device 
*dev, int cpu)
                 * Clear the broadcast bit for this cpu if the
                 * device is not power state affected.
                 */
-               if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+               if (!tick_broadcast_could_stop(dev))
                        cpumask_clear_cpu(cpu, tick_broadcast_mask);
                else
                        tick_device_setup_broadcast_func(dev);
@@ -368,7 +368,7 @@ void tick_broadcast_control(enum tick_broadcast_mode mode)
        /*
         * Is the device not affected by the powerstate ?
         */
-       if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
+       if (!dev || !tick_broadcast_could_stop(dev))
                goto out;
 
        if (!tick_device_is_functional(dev))
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 59225b484e4e..a300ee941c56 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -72,7 +72,7 @@ int tick_is_oneshot_available(void)
 
        if (!dev || !(dev->features & CLOCK_EVT_FEAT_ONESHOT))
                return 0;
-       if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
+       if (!tick_broadcast_could_stop(dev))
                return 1;
        return tick_broadcast_oneshot_available();
 }
@@ -393,7 +393,7 @@ int tick_broadcast_oneshot_control(enum 
tick_broadcast_state state)
 {
        struct tick_device *td = this_cpu_ptr(&tick_cpu_device);
 
-       if (!(td->evtdev->features & CLOCK_EVT_FEAT_C3STOP))
+       if (!tick_broadcast_could_stop(td->evtdev))
                return 0;
 
        return __tick_broadcast_oneshot_control(state);
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 7b2496136729..99aa7b5a8dae 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -2,6 +2,7 @@
 /*
  * tick internal variable and functions used by low/high res code
  */
+#include <linux/cpuidle.h>
 #include <linux/hrtimer.h>
 #include <linux/tick.h>
 
@@ -48,6 +49,17 @@ static inline void clockevent_set_state(struct 
clock_event_device *dev,
        dev->state_use_accessors = state;
 }
 
+/**
+ * Return true if the cpu could go in states where the device will be stopped
+ */
+static inline int tick_broadcast_could_stop(struct clock_event_device *dev)
+{
+       struct cpuidle_driver *drv = cpuidle_get_driver();
+
+       return !!((dev->features & CLOCK_EVT_FEAT_C3STOP)
+                 && drv && drv->bctimer);
+}
+
 extern void clockevents_shutdown(struct clock_event_device *dev);
 extern void clockevents_exchange_device(struct clock_event_device *old,
                                        struct clock_event_device *new);
-- 
2.15.0

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