Hi Mark,
the asoc generic ac97 codec support throws a warning on 2.6.29:
Advanced Linux Sound Architecture Driver Version 1.0.18a. No device for DAI WM8731 No device for DAI au1xpsc_i2s No device for DAI au1xpsc_ac97 AC97 SoC Audio Codec 0.6 asoc: AC97 HiFi <-> au1xpsc_ac97 mapping ok kobject (8f9279ec): tried to init an initialized object, something is seriously wrong. Call Trace: [<80106bcc>] dump_stack+0x8/0x34 [<8022c680>] kobject_init+0x50/0xcc [<8026d914>] device_initialize+0x2c/0x9c [<8026e274>] device_register+0x14/0x28 [<802ff2b8>] snd_soc_init_card+0x18c/0x24c [<803024a4>] ac97_soc_probe+0x12c/0x178 [<802fe76c>] snd_soc_instantiate_cards+0x1d4/0x2f4 [<802fe8fc>] soc_probe+0x70/0xb8 [<8027044c>] driver_probe_device+0xe0/0x1b8 [<8026f884>] bus_for_each_drv+0x60/0xb0 [<80270670>] device_attach+0x60/0x88 [<8026f63c>] bus_attach_device+0x38/0x94 [<8026e0cc>] device_add+0x390/0x524 [<80271a90>] platform_device_add+0x14c/0x1bc [<80462bd4>] db1200_audio_load+0xd8/0x10c [<801090e0>] __kprobes_text_end+0x60/0x1c8 [<804532d0>] kernel_init+0x9c/0x108 [<8010cf90>] kernel_thread_helper+0x10/0x18
ALSA device list: #0: DB1200 AC97 Audio (AC97)
The asoc machine code is very similar to sound/soc/au1x/sample-ac97.c (full source here: http://mlau.at/db1200.c).
I didn't bisect it; however it started after the first ASoC patches went in mainline after 2.6.28's release.
Please have a look!
Thanks, Manuel Lauss