linux omap2 git: add patch to surpress spurious timer reprogramming

1 files changed, 43 insertions, 0 deletions

diff --git a/packages/linux/linux-omap2-git/beagleboard/timer-suppression.patch b/packages/linux/linux-omap2-git/beagleboard/timer-suppression.patch
new file mode 100644
index 0000000000..04362c96e3
--- /dev/null
+++ b/packages/linux/linux-omap2-git/beagleboard/timer-suppression.patch
@@ -0,0 +1,43 @@
+diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
+index b854a89..26f5569 100644
+--- a/kernel/time/tick-sched.c
++++ b/kernel/time/tick-sched.c
+@@ -253,6 +253,16 @@ void tick_nohz_stop_sched_tick(void)
+ 
+ 	/* Schedule the tick, if we are at least one jiffie off */
+ 	if ((long)delta_jiffies >= 1) {
++		/*
++		 * calculate the expiry time for the next timer wheel
++		 * timer
++		 */
++		expires = ktime_add_ns(last_update, tick_period.tv64 *
++					delta_jiffies);
++
++		/* Skip reprogram of event if its not changed */
++		if(ts->tick_stopped && ktime_equal(expires, dev->next_event))
++		goto out2;
+ 
+ 		if (delta_jiffies > 1)
+ 			cpu_set(cpu, nohz_cpu_mask);
+@@ -304,12 +314,7 @@ void tick_nohz_stop_sched_tick(void)
+ 			goto out;
+ 		}
+ 
+-		/*
+-		 * calculate the expiry time for the next timer wheel
+-		 * timer
+-		 */
+-		expires = ktime_add_ns(last_update, tick_period.tv64 *
+-				       delta_jiffies);
++		/* Mark expiries */
+ 		ts->idle_expires = expires;
+ 
+ 		if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
+@@ -328,6 +333,7 @@ void tick_nohz_stop_sched_tick(void)
+ 		tick_do_update_jiffies64(ktime_get());
+ 		cpu_clear(cpu, nohz_cpu_mask);
+ 	}
++out2:	
+ 	raise_softirq_irqoff(TIMER_SOFTIRQ);
+ out:
+ 	ts->next_jiffies = next_jiffies;