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authorStephen Boyd <sboyd@codeaurora.org>2013-04-17 10:26:06 -0700
committerThomas Gleixner <tglx@linutronix.de>2013-04-17 21:30:56 +0200
commitc038c1c44179c80da6201f91ef354e48d5689617 (patch)
treea1ee34eadd567393cbdb6632ad7b8abb4a2fc4ea /kernel
parentb3956a896ea57f25cacd74708b8fab611543a81d (diff)
downloadop-kernel-dev-c038c1c44179c80da6201f91ef354e48d5689617.zip
op-kernel-dev-c038c1c44179c80da6201f91ef354e48d5689617.tar.gz
clockevents: Switch into oneshot mode even if broadcast registered late
tick_oneshot_notify() is used to notify a particular CPU to try to switch into oneshot mode after a oneshot capable tick device is registered and tick_clock_notify() is used to notify all CPUs to try to switch into oneshot mode after a high res clocksource is registered. There is one caveat; if the tick devices suffer from FEAT_C3_STOP we don't try to switch into oneshot mode unless we have a oneshot capable broadcast device already registered. If the broadcast device is registered after the tick devices that have FEAT_C3_STOP we'll never try to switch into oneshot mode again, causing us to be stuck in periodic mode forever. Avoid this scenario by calling tick_clock_notify() after we register the broadcast device so that we try to switch into oneshot mode on all CPUs one more time. [ tglx: Adopted to timers/core and added a comment ] Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Link: http://lkml.kernel.org/r/1366219566-29783-1-git-send-email-sboyd@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/tick-broadcast.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index d76d816..f8d2109 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -75,6 +75,16 @@ int tick_check_broadcast_device(struct clock_event_device *dev)
tick_broadcast_device.evtdev = dev;
if (!cpumask_empty(tick_broadcast_mask))
tick_broadcast_start_periodic(dev);
+ /*
+ * Inform all cpus about this. We might be in a situation
+ * where we did not switch to oneshot mode because the per cpu
+ * devices are affected by CLOCK_EVT_FEAT_C3STOP and the lack
+ * of a oneshot capable broadcast device. Without that
+ * notification the systems stays stuck in periodic mode
+ * forever.
+ */
+ if (dev->features & CLOCK_EVT_FEAT_ONESHOT)
+ tick_clock_notify();
return 1;
}
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