linux-kernel - Re: irq 16: nobody cared

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Message-ID: <20130422144402.GK3509@linux.vnet.ibm.com>
Date:	Mon, 22 Apr 2013 07:44:02 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Takashi Iwai <tiwai@...e.de>,
	x86-ml <x86@...nel.org>, lkml <linux-kernel@...r.kernel.org>
Subject: Re: irq 16: nobody cared

On Mon, Apr 22, 2013 at 04:23:56PM +0200, Borislav Petkov wrote:
> On Mon, Apr 22, 2013 at 02:56:08PM +0200, Thomas Gleixner wrote:
> > Boris, can you please provide the irq16 line of /proc/interrupts
> > before you invoke suspend?
> >
> > If it's shared we know which driver is shutdown before hda_intel and
> > perhaps leaves its device in a weird state.
> >
> > If it's not shared, it still might be shared behind the scene. The
> > other device uses MSI(X) and when shutdown MSI is disabled so the
> > default IRQ route which points to IRQ16 would be active again.
> >
> > I assume, that the RCU stuff just causes enough timing difference to
> > uncover the underlying issue.
> 
> Hmm, as Takashi reminded me, this box has two audio controllers. So
> could it be that when we shutdown and disable MSI, the interrupts get
> routed to to IRQ16 and they overflow there? Just a wild guess, I guess.

Would it make sense to try shutting off the hardware, waiting (say)
100 milliseconds, then diabling the irq?  (Hey, had to ask!)

							Thanx, Paul

> I very well can imagine that those two audio controllers to be one where
> some f*cked up BIOS shim switches between the two but can't keep them
> apart properly.
> 
> Something like the HPET fiascos...
> 
> * This is irq counts with my patch to expedite RCU grace periods:
> 
> - before suspend:
> # grep snd /proc/interrupts
>   16:       1304       1340       1335       1329       1293       1348       1357       1363   IO-APIC-fasteoi   snd_hda_intel
>   90:          3          3          4          4          4          4          3          3   PCI-MSI-edge      snd_hda_intel
> 
> - after resume:
> # grep snd /proc/interrupts
>   16:       1354       1389       1386       1380       1344       1400       1409       1495   IO-APIC-fasteoi   snd_hda_intel
>   90:          0          0          0          0          0          0          0          5   PCI-MSI-edge      snd_hda_intel
> 
> 
> * "normal" RCU grace periods:
> 
> - before suspend:
> # grep snd /proc/interrupts
>   16:        109        108        107        108        108        108        109        111   IO-APIC-fasteoi   snd_hda_intel
>   90:          3          3          4          4          4          4          3          3   PCI-MSI-edge      snd_hda_intel
> 
> - after resume:
> # grep snd /proc/interrupts
>   16:        154        154        153        155        157        157        235        164   IO-APIC-fasteoi   snd_hda_intel
>   90:          0          0          0          0          0          0          5          0   PCI-MSI-edge      snd_hda_intel
> 
> More "hmm.."
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> Sent from a fat crate under my desk. Formatting is fine.
> --
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