On 09/18/2013 08:48 PM, Soren Brinkmann wrote:
> 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@xxxxxxxxxx>
Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
> ---
> kernel/time/tick-broadcast.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
> index 218bcb5..9532690 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;
>
>
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