Ack: [PATCH Precise SRU] tick: Fix the spurious broadcast timer ticks after resume

[Brad Figg]

On 10/12/2012 11:32 AM, Tim Gardner wrote:
> From: Suresh Siddha <suresh.b.siddha at intel.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1065076
> 
> During resume, tick_resume_broadcast() programs the broadcast timer in
> oneshot mode unconditionally. On the platforms where broadcast timer
> is not really required, this will generate spurious broadcast timer
> ticks upon resume. For example, on the always running apic timer
> platforms with HPET, I see spurious hpet tick once every ~5minutes
> (which is the 32-bit hpet counter wraparound time).
> 
> Similar to boot time, during resume make the oneshot mode setting of
> the broadcast clock event device conditional on the state of active
> broadcast users.
> 
> Signed-off-by: Suresh Siddha <suresh.b.siddha at intel.com>
> Tested-by: Santosh Shilimkar <santosh.shilimkar at ti.com>
> Tested-by: svenjoac at gmx.de
> Cc: torvalds at linux-foundation.org
> Cc: rjw at sisk.pl
> Link: http://lkml.kernel.org/r/1334802459.28674.209.camel@sbsiddha-desk.sc.intel.com
> Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> (cherry picked from commit a6371f80230eaaafd7eef7efeedaa9509bdc982d)
> 
> Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
> ---
>  kernel/time/tick-broadcast.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
> index fd4a7b1..f61d678 100644
> --- a/kernel/time/tick-broadcast.c
> +++ b/kernel/time/tick-broadcast.c
> @@ -346,7 +346,8 @@ int tick_resume_broadcast(void)
>  						     tick_get_broadcast_mask());
>  			break;
>  		case TICKDEV_MODE_ONESHOT:
> -			broadcast = tick_resume_broadcast_oneshot(bc);
> +			if (!cpumask_empty(tick_get_broadcast_mask()))
> +				broadcast = tick_resume_broadcast_oneshot(bc);
>  			break;
>  		}
>  	}
> 


-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com