1 files changed, 21 insertions, 12 deletions

diff --git a/drivers/bus/arm-ccn.c b/drivers/bus/arm-ccn.c
index c826bb286054..12c1fd1bc398 100644
--- a/drivers/bus/arm-ccn.c
+++ b/drivers/bus/arm-ccn.c
@@ -940,15 +940,6 @@ static void arm_ccn_pmu_event_start(struct perf_event *event, int flags)
                         arm_ccn_pmu_read_counter(ccn, hw->idx));
         hw->state = 0;
 
-        /*
-         * Pin the timer, so that the overflows are handled by the chosen
-         * event->cpu (this is the same one as presented in "cpumask"
-         * attribute).
-         */
-        if (!ccn->irq)
-                hrtimer_start(&ccn->dt.hrtimer, arm_ccn_pmu_timer_period(),
-                                HRTIMER_MODE_REL_PINNED);
-
         /* Set the DT bus input, engaging the counter */
         arm_ccn_pmu_xp_dt_config(event, 1);
 }
@@ -962,9 +953,6 @@ static void arm_ccn_pmu_event_stop(struct perf_event *event, int flags)
         /* Disable counting, setting the DT bus to pass-through mode */
         arm_ccn_pmu_xp_dt_config(event, 0);
 
-        if (!ccn->irq)
-                hrtimer_cancel(&ccn->dt.hrtimer);
-
         /* Let the DT bus drain */
         timeout = arm_ccn_pmu_read_counter(ccn, CCN_IDX_PMU_CYCLE_COUNTER) +
                         ccn->num_xps;
@@ -1122,15 +1110,31 @@ static void arm_ccn_pmu_event_config(struct perf_event *event)
         spin_unlock(&ccn->dt.config_lock);
 }
 
+static int arm_ccn_pmu_active_counters(struct arm_ccn *ccn)
+{
+        return bitmap_weight(ccn->dt.pmu_counters_mask,
+                             CCN_NUM_PMU_EVENT_COUNTERS + 1);
+}
+
 static int arm_ccn_pmu_event_add(struct perf_event *event, int flags)
 {
         int err;
         struct hw_perf_event *hw = &event->hw;
+        struct arm_ccn *ccn = pmu_to_arm_ccn(event->pmu);
 
         err = arm_ccn_pmu_event_alloc(event);
         if (err)
                 return err;
 
+        /*
+         * Pin the timer, so that the overflows are handled by the chosen
+         * event->cpu (this is the same one as presented in "cpumask"
+         * attribute).
+         */
+        if (!ccn->irq && arm_ccn_pmu_active_counters(ccn) == 1)
+                hrtimer_start(&ccn->dt.hrtimer, arm_ccn_pmu_timer_period(),
+                              HRTIMER_MODE_REL_PINNED);
+
         arm_ccn_pmu_event_config(event);
 
         hw->state = PERF_HES_STOPPED;
@@ -1143,9 +1147,14 @@ static int arm_ccn_pmu_event_add(struct perf_event *event, int flags)
 
 static void arm_ccn_pmu_event_del(struct perf_event *event, int flags)
 {
+        struct arm_ccn *ccn = pmu_to_arm_ccn(event->pmu);
+
         arm_ccn_pmu_event_stop(event, PERF_EF_UPDATE);
 
         arm_ccn_pmu_event_release(event);
+
+        if (!ccn->irq && arm_ccn_pmu_active_counters(ccn) == 0)
+                hrtimer_cancel(&ccn->dt.hrtimer);
 }
 
 static void arm_ccn_pmu_event_read(struct perf_event *event)