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authorSoren Brinkmann <soren.brinkmann@xilinx.com>2013-09-18 11:48:37 -0700
committerDaniel Lezcano <daniel.lezcano@linaro.org>2013-10-02 11:34:06 +0200
commit245a34962661cd2ce7b4dd6c4aa65d870a589c50 (patch)
tree4357ebc8e9d90ca4bffd30c32438bc679ba1edcd /kernel/time/tick-broadcast.c
parent6661039dc906bce5d532477f26c7c965f25e5d02 (diff)
downloadlinux-245a34962661cd2ce7b4dd6c4aa65d870a589c50.tar.bz2
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>
Diffstat (limited to 'kernel/time/tick-broadcast.c')
-rw-r--r--kernel/time/tick-broadcast.c1
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;