Created attachment 643116 [details]
Xorg.1.log

[    22.435] (II) config/udev: Adding drm device (/dev/dri/card0)
[    22.436] (II) config/udev: Adding input device HD-Audio Generic HDMI/DP,pcm=3 (/dev/input/event14)
[    22.436] (II) No input driver specified, ignoring this device.
[    22.436] (II) This device may have been added with another device file.

does it show up in pavucontrol? if not, this is a PA issue and nothing to do with GNOME.

Yes, pavucontrol shows it as "Turks/Whistler HDMI Audio [Radeon HD 6000 Series] Digital Stereo (HDMI)" and it is the default device (check mark on green circle).  The device also appears in the output from alsa-info.sh which I attached in the original Description.  The device works in Windows Vista using HDMI cable to 1920x1080 monitor with stereo speakers.

The pavucontrol shows both the digital and analog sides of the builtin (on mainboard) audio as one device [on Configuration tab] with many modes, and with the HDMI audio as a different device.  The System Settings > Sound splits the builtin audio into analog and digital pieces, and omits the HDMI digital device.  If I plug in headphones to the front panel, then System Settings > Sound shows three devices ("Digital Output (S/PDIF) - Built-in Audio", "Analog Output - Built-in Audio", "Headphones - Built-in Audio"), while pavucontrol sees no difference (just two: HDMI and Builtin).

Hi John,

Are you booting with the HDMI cable connected? Does the audio device reappear if you remove the cable and plug it back in, while the system is running? What does 'dmesg' show regarding the HDMI?

According to the alsa-info output you posted, the HDMI connector was unplugged, at the time you ran alsa-info.

This also likely the reason why it isn't shown in System Settings -- it's only showing devices that are actually plugged in, according to the kernel. Pavucontrol on the other hand doesn't hide unplugged devices, which is why the device is listed there.

Looks like an ALSA/kernel bug to me. Reassigning to kernel.

HDMI audio is disabled by default on radeon.

commit 805c22168da76a65c978017d0fe0d59cd048e995
Author: Alex Deucher <alexdeucher>
Date:   Mon Jun 6 17:39:16 2011 -0400

    drm/radeon/kms: disable hdmi audio by default
    
    The current RE'd code causes blank screens and
    display problems on a lot of systems.  So disable
    it by default for now.  It can still be enabled
    by setting the audio parameter to 1.  E.g.:
    radeon.audio=1

(In reply to comment #4)
> Are you booting with the HDMI cable connected? Does the audio device
> reappear if you remove the cable and plug it back in, while the system is
> running? What does 'dmesg' show regarding the HDMI?

Yes, the HDMI cable is connected at boot.  After logging in, unplugging and re-plugging the HDMI cable: then re-invoking System Settings > Sound still does not show HDMI audio.

$ dmesg | grep HDMI
[    3.362410] [drm]   HDMI-A-1
[   15.789406] input: HD-Audio Generic HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input14

Skipping ahead to comment #6, if I boot with kernel command line parameter "radeon.audio=1" then 

$ dmesg | grep HDMI
[    2.472250] [drm]   HDMI-A-1
[   11.261120] ALSA sound/pci/hda/hda_eld.c:337 HDMI: ELD buf size is 0, force 128
[   11.261135] ALSA sound/pci/hda/hda_eld.c:356 HDMI: invalid ELD data byte 0
[   11.261219] input: HD-Audio Generic HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input14

and Sound shows HDMI audio, and the speakers work.

(In reply to comment #5)
> According to the alsa-info output you posted, the HDMI connector was
> unplugged, at the time you ran alsa-info.

Yes, I was using only DVI-D for that run.

> This also likely the reason why it isn't shown in System Settings -- it's
> only showing devices that are actually plugged in, according to the kernel.
> Pavucontrol on the other hand doesn't hide unplugged devices, which is why
> the device is listed there.

Much like NetworkManager shows "(cable unplugged)" when configuring network interfaces, then I expect that Sound will show all the actual sound hardware and status.  [For comparison, in Windows I have seen four different graphical apps (native, VIA, XFX[radeon], nVidia) each showing all audio devices, whether or not an associated cable is plugged in.  If there is no cable detected then that device is grayed out, but it is listed.]  List the "connected and ready" interfaces first if you wish, but I don't appreciate having to plug in a cable to every interface just to see the list of hardware devices that would [should] work if I did.  Yes, I could use "lspci" but I also want the presentation that Sound [should] give, including "virtual" devices that lspci does not show.

(In reply to comment #7)
> Skipping ahead to comment #6, if I boot with kernel command line parameter
> "radeon.audio=1" then 
> 
> $ dmesg | grep HDMI
> [    2.472250] [drm]   HDMI-A-1
> [   11.261120] ALSA sound/pci/hda/hda_eld.c:337 HDMI: ELD buf size is 0,
> force 128
> [   11.261135] ALSA sound/pci/hda/hda_eld.c:356 HDMI: invalid ELD data byte 0
> [   11.261219] input: HD-Audio Generic HDMI/DP,pcm=3 as
> /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input14
> 
> and Sound shows HDMI audio, and the speakers work.

Great.