After upgrading from 3.8.11-200.fc18.x86_64 to 3.9.2-200.fc18.x86_64 (and 3.9.4) sound output through headphones has stopped working. Rebooting with 3.8.11 and no other changes makes headphone sound work again.

Sound output through the built-in speakers works fine on both kernels.

This problem sounds a lot like bug 917409 or bug 904883, but in my case it's apparently dependent on the kernel version only.

With 3.9 the headphones are still properly detected; the output device in Gnome sound preferences changes when headphones are plugged in and out.

The hardware is a generic Intel Ivy Bridge based laptop; lspci gives

00:1b.0 Audio device: Intel Corporation 7 Series/C210 Series Chipset Family High Definition Audio Controller (rev 04)

The ALSA related parts of dmesg are the same on all kernels except for the line numbers; in 3.9.4 it is
 
[    4.119770] ALSA sound/pci/hda/hda_auto_parser.c:335 autoconfig: line_outs=1 (0x24/0x0/0x0/0x0/0x0) type:speaker
[    4.119772] ALSA sound/pci/hda/hda_auto_parser.c:339    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    4.119774] ALSA sound/pci/hda/hda_auto_parser.c:343    hp_outs=1 (0x25/0x0/0x0/0x0/0x0)
[    4.119775] ALSA sound/pci/hda/hda_auto_parser.c:344    mono: mono_out=0x0
[    4.119776] ALSA sound/pci/hda/hda_auto_parser.c:348    inputs:
[    4.119778] ALSA sound/pci/hda/hda_auto_parser.c:352      Mic=0x2b
[    4.119779] ALSA sound/pci/hda/hda_auto_parser.c:352      Internal Mic=0x29