[Sound] AC97 codec ready in one computer and not ready in the other.

[Miguel Quirós <mquiros@xxxxxx>]

Hello, I am trying to make the sound work in two computers that are
supoused to have identical hardware.

Both have, (according to information from Windows) an Avance AC97 audio
card. Sound works under Windows for both computers.

I have installed Red Hat 7.3 for both but the original kernel has been
replaced by 2.4.20. For my surprise, sound works perfectly in one of the
computers but it does not in the other.

In computer #1, after modprobe i810_audio, the modules soundcore,
ac97_codec and i810_audio are loaded and the sound works nicely. At the
end of /var/log/messages I can read:

Apr  2 15:48:18 puma1 kernel: Intel 810 + AC97 Audio, version 0.21,
10:14:07 Mar 17 2003
Apr  2 15:48:18 puma1 kernel: PCI: Found IRQ 11 for device 00:1f.5
Apr  2 15:48:18 puma1 kernel: PCI: Sharing IRQ 11 with 00:1f.3
Apr  2 15:48:18 puma1 kernel: PCI: Sharing IRQ 11 with 01:01.0
Apr  2 15:48:18 puma1 kernel: i810: Intel ICH4 found at IO 0xe400 and
0xe000, IRQ 11
Apr  2 15:48:18 puma1 kernel: i810_audio: Audio Controller supports 6
channels.
Apr  2 15:48:18 puma1 kernel: ac97_codec: AC97 Audio codec, id:
ALG16(ALC200/200P)
Apr  2 15:48:18 puma1 kernel: i810_audio: AC'97 codec 0 supports AMAP,
total channels = 2

But in computer #2, modprobe i810_audio fails, if I try modprobe -v, I
can see that soundcore and ac97_codec are first loaded and then unloaded
when i810_audio loading fails. Output in /var/log/messages is in this
case:

Apr  2 09:40:01 puma2 kernel: Intel 810 + AC97 Audio, version 0.21,
10:14:07 Mar 17 2003
Apr  2 09:40:01 puma2 kernel: PCI: Found IRQ 11 for device 00:1f.5
Apr  2 09:40:01 puma2 kernel: PCI: Sharing IRQ 11 with 00:1f.3
Apr  2 09:40:01 puma2 kernel: PCI: Sharing IRQ 11 with 01:01.0
Apr  2 09:40:01 puma2 kernel: i810: Intel ICH4 found at IO 0xe400 and
0xe000, IRQ 11
Apr  2 09:40:02 puma2 kernel: i810_audio: Audio Controller supports 6
channels.
Apr  2 09:40:02 puma2 kernel: i810_audio: Primary codec not ready.

I can load ac97_codec and soundcore without errors with insmod but if I
try after that insmod i810_audio, loading still fails.

I cannot understand why the "primary codec is not ready" for computer
#2. Perhaps the hardware of both computers is not as identical as it
should be and that in computer #2 is not supported?
How could I find if the hardware is indeed different (as far as I can
see, lspci yields exactly the same result for both computers)?
Perhaps the card must be initialized or something like that?
Could it be a software misconfiguration somewhere? 
I have checked some important files: vmlinuz-2.4.20, System-map-2.4.20,
and module files with md5sum to be sure that they are absolutely
identical in both machines.

Thanks for any help.

-- 
-------------------------
Miguel Quirós Olozábal
Departamento de Química Inorgánica. Facultad de Ciencias.
Universidad de Granada. 18071 Granada (SPAIN).
email:mquiros@xxxxxx