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From: Jens Rottmann <JRottmann@LiPPERTEmbedded.de>
To: Thomas Gleixner <tglx@linutronix.de>, John Stultz <johnstul@us.ibm.com>
Cc: Andres Salomon <dilinger@queued.net>,
	linux-kernel@vger.kernel.org, linux-geode@lists.infradead.org
Subject: [PATCH resend] cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels
Date: Mon, 06 Feb 2012 09:20:33 +0100	[thread overview]
Message-ID: <4F2F8D51.1010504@LiPPERTEmbedded.de> (raw)
In-Reply-To: <20111214104724.292b02d4@queued.net>

cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels

On SMP-capable kernels (e.g. generic distro kernel) the cs5535-clockevt driver
loads but is not actually used.

Setting cpumask to cpu_all_mask works for UP-only kernels, but if compiled for
SMP - though still running on the same UP hardware -
kernel/time/tick-common.c:tick_check_new_device() reads this as "non-cpu-local"
and silently ignores the device.

If we leave cpumask unset clockevents_register_device() will initialize it and
the cs5535-clockevt driver will be used no matter how the kernel was compiled.
Should anyone ever manage to stick a CS553x in an SMP system (is this even
possible?) then a warning will be printed.  This is fine as the cs5535-clockevt
driver was never written/tested for SMP.

If bisecting led you here this patch may have exposed a pre-existing MFGPT
problem.  Configure for UP-only and re-check.

Signed-off-by: Jens Rottmann <JRottmann@LiPPERTEmbedded.de>
Acked-by: Andres Salomon <dilinger@queued.net>
---

Hi again,

could you please take this, for linux-next?

Thanks,
Jens

--- linux-3.2-rc6/drivers/clocksource/cs5535-clockevt.c
+++ use_mfgpt_on_smp_kernels/drivers/clocksource/cs5535-clockevt.c
@@ -100,7 +100,6 @@ static struct clock_event_device cs5535_
 	.set_mode = mfgpt_set_mode,
 	.set_next_event = mfgpt_next_event,
 	.rating = 250,
-	.cpumask = cpu_all_mask,
 	.shift = 32
 };
 
_



  parent reply	other threads:[~2012-02-06  8:27 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-12 15:41 IRQF_TIMER | IRQF_SHARED ? Jens Rottmann
2011-12-12 20:31 ` Andres Salomon
2011-12-12 21:00   ` Martin-Éric Racine
2011-12-12 22:06     ` Andres Salomon
2011-12-12 23:38   ` Thomas Gleixner
2011-12-13 15:49   ` Jens Rottmann
2011-12-14 18:37     ` Jens Rottmann
2011-12-14 18:47       ` Andres Salomon
2011-12-21 15:42         ` [PATCH] cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels Jens Rottmann
2012-01-11 10:10           ` Andres Salomon
2012-01-19 12:57             ` Jens Rottmann
2012-01-23 10:44               ` Andres Salomon
2011-12-21 16:37         ` IRQF_TIMER | IRQF_SHARED ? Jens Rottmann
2011-12-22 16:35         ` [PATCH] cs5535-clockevt: allow the MFGPT IRQ to be shared Jens Rottmann
2012-01-11 10:15           ` Andres Salomon
2012-01-30 13:51         ` [PATCH] cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels Jens Rottmann
2012-01-30 13:59         ` [PATCH] cs5535-clockevt: allow the MFGPT IRQ to be shared Jens Rottmann
2012-02-06  8:20         ` Jens Rottmann [this message]
2012-02-06  8:23         ` [PATCH resend] " Jens Rottmann
2011-12-19 14:32       ` "clockevents: Set noop handler in clockevents_exchange_device()" causes hang with cs5535-clockevt Jens Rottmann

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