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SubjectRe: 2.6.19-rc1: known regressions (v2)
Date
Am Samstag 07 Oktober 2006 23:46 schrieb Adrian Bunk:
> Subject : snd-hda-intel <-> forcedeth MSI problem
> References : http://lkml.org/lkml/2006/10/5/40
> Submitter : Prakash Punnoor <prakash@punnoor.de>
> Status : unknown

AFAIK, strictly speaking this is not a regression, but rather a new feature
breaking: MSI capability of snd-hda-intel. Alsa dev
Takashi Iwai doesn't think it is snd-hda-intel doing something wrong, but
rather an IRQ routing probem. As such I am not sure who to cc....
While I don't really understand the details, I guess it is due to snd and net
sharing the interrupt in "pure" APIC more:

23: 232796 0 IO-APIC-fasteoi HDA Intel, eth0

So both are physically on the same INT line? But MSI of snd want to assign
another IRQ to itself:

23: 7486 0 IO-APIC-fasteoi eth0
316: 0 0 PCI-MSI-edge HDA Intel

So it seems that irq23 still receives signals from snd and thus the nobody
cared message gets printed.

Thus my work-around is simply to disable MSI of snd by
snd-hda-intel.disable_msi=1 and all is well again.

So if this cannot be fixed for 2.6.19, I humbly suggest deactivating MSI of
snd-intel-hda by default.

Cheers,
--
(°= =°)
//\ Prakash Punnoor /\\
V_/ \_V
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