Sound doesn't work in Feisty on iMac 24

[Nicola Fagnani]

After a fresh install of Ubuntu 7.04 Feisty on my iMac 24'' Core 2 Duo, I can't hear any sound from the speakers.
I'd like to point out that this is not the same problem occurring with other iMacs. It seems that the chipset used by this model is the Realtek ALC885 while a patch recently applied to alsa project source code for iMac refers to the Sigmatel chipset.
In fact I found a workaround using a recent snapshot of alsa (post 1.0.14rc3) and forcing the model option for the snd_hda_intel module to macpro. See here for details:

http://ubuntuforums.org/showpost.php?p=2549232&postcount=13

While doing so I can hear sound from the speakers, I can't record sound and I don't know if other sound channels are ok, e.g. spdif out or headphone.

[Nicola Fagnani (nicfagn)]

tail -2 /proc/asound/oss/sndstat output

[Nicola Fagnani (nicfagn)]

There is a related bug on the bug tracking system of alsa project:

https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2708

[Nicola Fagnani (nicfagn)]

I think this is interesting, notice the Subsystem id: 0x106b1000

[PeterKnaggs (peter-knaggs)]

I can confirm that the patch posted by nicfagn works for digital optical output
(AC3 passthrough) too, see the "Audio" section of this page for details:
http://www.penlug.org/twiki/bin/view/Main/LinuxHardwareInfoAppleiMac24

[Nicola Fagnani (nicfagn)]

I submitted the above mentioned patch on the ALSA bug tracking system, with some minor improvements: an option to force the model to iMac24 and formal code adjustements.
The bug is here:

https://bugtrack.alsa-project.org/alsa-bug/view.php?id=2708

and the patch is here:

https://bugtrack.alsa-project.org/alsa-bug/file_download.php?file_id=2031&type=bug

[Nicola Fagnani (nicfagn)]

The patch has been integrated in the alsa code and it is in kernel code since 2.6.23-rc1.
Is it possible to have it in Gutsy or will have to wait for Gutsy+1?

[Wouter Stomp (wouterstomp-deactivatedaccount)]

Is this still an issue on gutsy and/or hardy?

[Nicola Fagnani (nicfagn)]

Sound is working in Hardy Alpha 4 but, as far as i know, it wasn't fixed in Gutsy.

[Wouter Stomp (wouterstomp-deactivatedaccount)]

Marking as fixed then.