From: santosh.shilimkar@ti•com (Santosh Shilimkar)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM: smp: Allow real broadcast device selection instead of always dummy
Date: Wed, 13 Mar 2013 14:58:22 +0530 [thread overview]
Message-ID: <514046B6.9020005@ti.com> (raw)
In-Reply-To: <1363165608-13739-1-git-send-email-santosh.shilimkar@ti.com>
(Forgot to CC Thomas)
On Wednesday 13 March 2013 02:36 PM, Santosh Shilimkar wrote:
> With recent arm broadcast time clean-up from Mark Rutland, the dummy
> broadcast device is always registered with timer subsystem. And since
> the rating of the dummy clock event is very high, it is preferred
> over a real broad-cast clock event.
>
> This is a change in behavior from past and not an intended
> one. So reduce the rating of the dummy clockevent so that
> real broadcast device is selected when available.
>
> Without this all the C states with C3STOP won't work since
> the broad cast notifier will take an abort.
>
> Cc: Mark Rutland <mark.rutland@arm•com>
> Cc: Russell King <linux@arm•linux.org.uk>
>
> Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti•com>
> ---
> Its a regression so hopefully can get into the 3.9-rcx. Noticed
> this one on A15 platform. A9 platform the issue may not be seen
> since the local timer check avoids dummy timer registration.
>
Some one pointed me to a fix made by Mark which was discussed
under '[BUG] ARM Architected timers appear broken in 3.9-rc1' subject.
That patch seems to be more of work around since the root of the
problem is incorrect dummy timer rating. Either way, both patches
fix the issue.
> arch/arm/kernel/smp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
> index 31644f1..79078ed 100644
> --- a/arch/arm/kernel/smp.c
> +++ b/arch/arm/kernel/smp.c
> @@ -480,7 +480,7 @@ static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
> evt->features = CLOCK_EVT_FEAT_ONESHOT |
> CLOCK_EVT_FEAT_PERIODIC |
> CLOCK_EVT_FEAT_DUMMY;
> - evt->rating = 400;
> + evt->rating = 100;
> evt->mult = 1;
> evt->set_mode = broadcast_timer_set_mode;
>
>
next prev parent reply other threads:[~2013-03-13 9:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-13 9:06 [PATCH] ARM: smp: Allow real broadcast device selection instead of always dummy Santosh Shilimkar
2013-03-13 9:28 ` Santosh Shilimkar [this message]
2013-03-13 10:16 ` Mark Rutland
2013-03-13 11:24 ` Santosh Shilimkar
2013-03-13 12:25 ` Mark Rutland
2013-03-13 15:44 ` Santosh Shilimkar
2013-03-13 16:18 ` Mark Rutland
2013-03-14 7:45 ` Santosh Shilimkar
2013-03-14 8:50 ` Thomas Gleixner
2013-03-14 10:28 ` Mark Rutland
2013-03-14 10:46 ` Santosh Shilimkar
2013-03-14 19:41 ` Stephen Boyd
2013-03-13 14:19 ` Thomas Gleixner
2013-03-13 15:37 ` Santosh Shilimkar
2013-03-13 18:31 ` Thomas Gleixner
2013-03-14 6:09 ` Santosh Shilimkar
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