Apple iMac 12,1 and 13,1 models (21.5 or 27 inch) well supported by Linux but there is an annoying problem with sound card.
Builtin speakers works out of the box but when you plugged headphones, you can't hear any sound on it though it will detected properly (at least Debian Jessie edition).
There is already an open bug report for this problem: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=743936
To fix this problem, you have to load
snd-hda-intel module with
To do this, create a new file (if similar conf file for snd-hda-intel module exists, use that one) for example
/etc/modprobe.d/sound.conf with following content:
options snd-hda-intel model=imac27_122
and reboot, that's all.
Do not try any other model parameters which you may found on some forum sites, it will not work for these Apple iMac models.
You can learn your device's model name with
dmidecode as below:
$ sudo dmidecode | grep "Product Name"
Product Name: iMac13,1