nouveau optimus HDMI audio support

[Jethro Beekman]

Even with Dave Airlie's recent patch set (
http://lists.freedesktop.org/archives/dri-devel/2013-August/042854.html ), I'm
still having trouble getting HDMI audio to work on my optimus laptop. I'm
running Linux 3.12.0-rc3 on a Lenovo ThinkPad T420s. When I set my BIOS graphics
option to 'Discrete', I get the following two devices in lspci:

01:00.0 VGA compatible controller: NVIDIA Corporation GF119 [Quadro NVS 4200M]
(rev a1)
01:00.1 Audio device: NVIDIA Corporation HDMI Audio stub (rev a1)

When I set the option to 'Optimus', the 01:00.1 device disappears completely.
This is dmesg when loading nouveau in the Optimus configuration:

pci 0000:01:00.0: optimus capabilities: enabled, status dynamic power, hda bios
codec supported
VGA switcheroo: detected Optimus DSM method \_SB_.PCI0.PEG_.VID_ handle
[drm] hdmi device  not found 1 0 1

I modified snd-hda-intel to report which devices it's probing, this is the only
one that shows up:

hda-intel: azx_probe: 0000:00:1b.0

Any ideas what's going on?

Jethro Beekman