This sounds like a plausible explanation, thanks! I didn't think the ATI HDMI audio controller used the intel-hda module too.

I haven't had a chance to test HDMI audio yet, but I will give it a try soon.
Thanks for the help!

Tommaso

2011/8/19 Takashi Iwai <tiwai@suse.de>
At Fri, 19 Aug 2011 12:14:33 +0200,
Tommaso Falchi Delitala wrote:
>
> I noticed that error messages
>
> hda-intel: spurious response ....
> hda-intel: azx_get_response timeout, switching to polling mode:
> ...
> hda_intel: azx_get_response timeout, switching to single_cmd mode
>
> are present in dmesg only when Intel integrated graphic card is used. The
> system has two GPUs (Intel + ATI dedicated).
> If ATI card is selected at boot (using vga_switcheroo) no such messages are
> displayed.
>
> Is there any logical explanation to this behavior?

Your machine have two HD-audio controllers, one for on-board audio
and another for HDMI.  HDMI looks like ATI D-GPU, and this confuses
the system when GPU isn't active.  It seems that HDMI controller
doesn't respond when GPU is disabled.

A question is whether HDMI really works when D-GPU is enabled.
Did you test it?


Takashi