[alsa-devel] Releasing IRQs in older kernels

Risto Suominen risto.suominen at gmail.com
Mon Apr 14 22:48:15 CEST 2008

I'd like to bring up a problem with using alsa-driver on older
kernels. I already made a bug report regarding snd-powermac:
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3883. It's
possible that other drivers suffer from this, too.

If I've understood it right, 1.0.16 should be usable on 2.2 kernels
and newer. Well, it woudn't compile on 2.6.15-26-powerpc (Ubuntu
6.06.1 Dapper) without some patching.

However, the real problem began, when I tried to unload the module. It
seems that something has changed (when?) in the kernel's IRQ
interface, and ALSA tries to make old code compatible with it by
introducing snd_request/free_irq, to be used with older kernels. The
idea is to distuingish between IRQs by the last parameter, usually
chip's address. This leads to trouble when several IRQs come from the
same chip, as is the case with snd-powermac.

My conclusion: the drivers suffering from this should be identified,
and some alternative way of handling IRQs correctly on different
kernel versions should be developed.


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