Shit, I sent my last message before completing it. The bug is
in auich.c. At around line 834 the code does this:

orate = play->sample_rate;
if (sc->sc_ac97rate != 0)
play->sample_rate = orate * AUICH_FIXED_RATE /
sc->sc_ac97rate;
error = ac97_set_rate(sc->codec_if, play, AUMODE_PLAY);
play->sample_rate = orate;

It does a similar thing to set the AUMODE_RECORD rate around line 876.

The problem is that ac97_set_rate may update the rate to a different
value than that requested and not signal an error. We clobber the
value set in ac97.c. I'm not sure what the proper thing to do
here, is.

// marc