Comment 7 for bug 305750

Thanks, David.

linux-backports-modules-alsa-karmic does indeed fix the issue on my Macbook 3,1 running karmic. The backport also fixes headphone detection trouble, e.g. speakers are now reliably muted when something is plugged into the headphone jack.

This can probably be closed as fix committed though ALSA still tracks the issue as "new", presumably due to a lack of positive test reports.