Re: [Alsa-user] Intel HDA: HDMI audio on i945GT

[Wil <no...@ho...>]

> Great. Just for my interest to know about tried/tested HTPC setups. Did
> you put the components you used somewhere?

I'm not sure where these things are listed it was an old purchase stuck into
an existing setup, to be honest I didn't think I was ever going to use it
again as I believe the NVidia ION is now a popular choice due to the HD
acceleration etc. The only reason I got this out again is because the
original motherboard has a broken SPDIF socket, it was an AOpen which used a
very flimsy plug to connect SPDIF through a specialised 3.5mm audio socket.
In this instance I'm only using the onboard hardware of the ABIT iL-90MV so
that really covers it all anyway.

> Was it hard to setup? Or did you just follow [1]?

Again because this was an old setup most of the config for the IEC was on
the backend server and some of it did require a lot of googling to find out
at the time, which was probably a couple of years ago now. But mainly it's
just the appropriate string to stuff into the mythtv setup (the original IEC
settings still work). Other than that the default gentoo build process
worked without too many issues I don’t recall doing anything special to
setup sound. 

> I have to say, that I do not if it will work. But I am pretty sure that
> chances are small that it will work right away. What prevents you from
> just trying it?

I've already tried, if you refer to the aplay -l listing there is no HDMI
connector available to use. 

> If it does not work you should also try the latest releases first.

I've given that a go and unfortunately it doesn't work. What I can say is
that I can trick the system into giving me an HDMI connector by patching the
code (patch_intelhdmi.c) but this of course doesn't give me a useable
device. It does however make me believe that the issue lies with the drivers
and not with something I've forgot to do?

The codec is presented as 0x10ec0882 (I believe that is a Realtek 882), the
hardware is listed as follows using lspci.

00:1b.0 Audio device [0403]: Intel Corporation 82801G (ICH7 Family) High
Definition Audio Controller [8086:27d8] (rev 02)

However afaik HDMI audio is sent using the SDVO interface of the Intel
graphics adapter and probably has little to do with the actual sound
hardware at all. It just needs an Alsa interface so other programs can
interface with it in the normal way.

I believe the process is that the video driver will need to detect the
relevant SDVO output firstly as HDMI and further as HDMI audio capable. I
believe that there is also a mechanism for reconfiguring the audio outputs
at this point. I've done some logging and I don't believe that the video
driver even detects that I have an HDMI connection. If I hard coded the
is_hdmi setting and SDVO_AUDIO_ENABLE there is still no change so I believe
whatever is going on is more complex than that. The problem is I'm not
entirely sure who to ask first, starting here seemed like a good idea as
Audio therefore Alsa. However it is possible that until the video driver is
setup to handle the 945GT chipset no progress can be made. Really at this
point I think I need some advice from the developers as working out how the
linking between the video driver and the audio driver operates may be
difficult. Thanks for your assistance and if you have any other ideas to
follow up on I may give them a try.

Will