From: Jens Rottmann <JRottmann@LiPPERTEmbedded.de>
To: Andres Salomon <dilinger@queued.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, linux-geode@lists.infradead.org
Subject: Re: IRQF_TIMER | IRQF_SHARED ?
Date: Wed, 14 Dec 2011 19:37:39 +0100 [thread overview]
Message-ID: <4EE8ECF3.6000900@LiPPERTEmbedded.de> (raw)
In-Reply-To: <4EE77416.8090907@LiPPERTEmbedded.de>
Jens Rottmann schrieb:
> Andres Salomon schrieb:
>> Just loading cs5535-clockevt should start the periodic timer.
>> On my XO-1, IRQ 7 starts firing immediately.
> Hmm, no, doesn't work. :-| In /proc/interrupts IRQ 0 gets increased,
> not (in my case) IRQ 11.
Update: I found that SMP-enabled kernels (like the generic one I was using) do
load cs5535-clockevt fine but ignore it and keep using the pit timer instead.
Responsible seems kernel/time/tick-common.c: tick_check_new_device()
/*
* If the cpu affinity of the device interrupt can not
* be set, ignore it.
*/
if (!irq_can_set_affinity(newdev->irq))
goto out_bc;
Looks like it has been that way for quite some time, maybe cs5535-clockevt
hasn't ever worked on SMP kernels.
If I turn off SMP, cs5535-clockevt replaces the pit timer and the MFGPT IRQ
starts firing just as you said - at least on 3.0.9. 3.2-rc5 prefers to hang
instead, looks like no timer events get generated. Sigh.
I'll try to narrow it down tomorrow, but now I'm calling it a day.
Cheers
Jens
next prev parent reply other threads:[~2011-12-14 18:37 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 [this message]
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 ` [PATCH resend] cs5535-clockevt: don't ignore MFGPT on SMP-capable kernels Jens Rottmann
2012-02-06 8:23 ` [PATCH resend] cs5535-clockevt: allow the MFGPT IRQ to be shared 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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