More on Blade 100/AC97 codec detection failure

J.C. Wren (jcwren@jcwren.com)
Sat, 31 May 2003 14:56:01 -0400


I've done a little bit more playing around, trying to get sound working on the
Blade 100. First, ac97_codec.c is reading an ID of 0x00000000 for the codec.
It's supposed to be 0x41445348 (AD1881A). I didn't have much hope that
forcing the codec ID to that value would solve anything, and sure enough, it
didn't. There are two ambiguous comments in the codec detection area:

/* probing AC97 codec, AC97 2.0 says that bit 15 of register 0x00
(reset) should
* be read zero.
*
* FIXME: is the following comment outdated? -jgarzik
* Probing of AC97 in this way is not reliable, it is not even SAFE !!
*/

So which is it?

I have talked to another person with a Blade 100, using 2.4.21-rc6 (I'm on
-rc4), and they have the EXACT same problem. So I'm not hallucinating,
unless we all shared the Koolaid.

I don't know the significance of this but using mpg123 to play a MP3 gives no
audio. Using mpg321 produces a loud hissing *way* over-amped audio that one
can vaguely here modulation on. It sounds like the rate is off somewhat, but
the only way I can even remotely tell that is to use a gain of 1 (-g 1) to
mpg321. To even get mpg123 to work, I had to modprobe in the 'dmy' device
and give it a fake /dev/audioctl to play with itself with.

The other person with the Blade 100 reported that 2.4.20-r8 produced the same
hissy results. However, there are reports of people using Debian with 2.4.18
having it work (http://www.de-brauwer.be/docs/debian_on_sun.html).

--jcwren

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