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| author | Soren Brinkmann <soren.brinkmann@xilinx.com> | 2013-09-18 20:48:37 +0200 |
|---|---|---|
| committer | Daniel Lezcano <daniel.lezcano@linaro.org> | 2013-10-02 11:34:06 +0200 |
| commit | 245a34962661cd2ce7b4dd6c4aa65d870a589c50 (patch) | |
| tree | 4357ebc8e9d90ca4bffd30c32438bc679ba1edcd | |
| parent | clocksource/arm_global_timer: Set FEAT_PERCPU flag (diff) | |
| download | linux-245a34962661cd2ce7b4dd6c4aa65d870a589c50.tar.xz linux-245a34962661cd2ce7b4dd6c4aa65d870a589c50.zip | |
tick: broadcast: Deny per-cpu clockevents from being broadcast sources
On most ARM systems the per-cpu clockevents are truly per-cpu in
the sense that they can't be controlled on any other CPU besides
the CPU that they interrupt. If one of these clockevents were to
become a broadcast source we will run into a lot of trouble
because the broadcast source is enabled on the first CPU to go
into deep idle (if that CPU suffers from FEAT_C3_STOP) and that
could be a different CPU than what the clockevent is interrupting
(or even worse the CPU that the clockevent interrupts could be
offline).
Theoretically it's possible to support per-cpu clockevents as the
broadcast source but so far we haven't needed this and supporting
it is rather complicated. Let's just deny the possibility for now
until this becomes a reality (let's hope it never does!).
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
| -rw-r--r-- | kernel/time/tick-broadcast.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 218bcb565fed..9532690daaa9 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -70,6 +70,7 @@ static bool tick_check_broadcast_device(struct clock_event_device *curdev, struct clock_event_device *newdev) { if ((newdev->features & CLOCK_EVT_FEAT_DUMMY) || + (newdev->features & CLOCK_EVT_FEAT_PERCPU) || (newdev->features & CLOCK_EVT_FEAT_C3STOP)) return false; |