Commit-ID: c038c1c44179c80da6201f91ef354e48d5689617 Gitweb: http://git.kernel.org/tip/c038c1c44179c80da6201f91ef354e48d5689617 Author: Stephen Boyd <sboyd@xxxxxxxxxxxxxx> AuthorDate: Wed, 17 Apr 2013 10:26:06 -0700 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 17 Apr 2013 21:30:56 +0200 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@xxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1366219566-29783-1-git-send-email-sboyd@xxxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- kernel/time/tick-broadcast.c | 10 ++++++++++ 1 file changed, 10 insertions(+) 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; } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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