Bug#529697: linux-image-2.6.26-2-686: Crystal 4237b audio card not working and causing kernel freeze during boot
> perhaps this means the severity should be lowered
I can't speak to that. I'm not a member of the Debian kernel team. I'm just an ordinary
end user who happened to notice a reference to the same kind of sound chip that I have
and thought I might be able to help.
The problem, as I see it, is two-fold. First, there is apparently a bug in the snd-cs4232
driver that causes a kernel oops. That bug has apparently been fixed in 2.6.27. But in your
situation (and mine), that driver shouldn't have been loaded in the first place. There
is another problem that requires a design change to fix, and I don't know how it's going
to be addressed. The idea behind the hot plug system is that kernel modules would be given
aliases corresponding to the device ids that they are to be drivers for. These device ids
can be listed by lspnp (in the pnputils package), lspci, lspcmcia, etc. If the hot plug
system finds a kernel module with an alias which matches a device id that it has been able
to detect, it loads that kernel module. That works most of the time.
Unfortunately, Crystal Semiconductor used the same device id, CSC0000, for too many
dissimilar devices. There are therefore three different drivers that have this alias:
snd-cs4232, snd-cs4236, and snd-wavefront. In any given situation, only one of them should
be loaded. The question is, which one? It is currently the design of the hot plug system
to load all drivers that have an alias matching the device id. That means it tries to load
all three of them. Either some additional smarts must be added to the hot plug system to
figure out which one is the right driver in this situation and load only that one, or else
the drivers themselves need to be smarter, so that they won't touch a sound chip that
another driver should be used for. And that's not a bug: that's a design change. In the
meantime, the work-around is to blacklist the drivers that you don't want. This is not
too bad when you're INSTALLING Linux, provided that you understand what's going on and how
to work around it. A smarter installer could solve that problem. But how would Debian Live
systems, which must figure out everything on the fly, know which driver to load? The kernel
people need to take a look at this. In a perfect world, it would be nice if Linux knew how
to configure ISA PnP devices on older IBM ThinkPads too, such as the 600. It is apparently
done in some kind of non-standard way. But I'm not holding my breath.
Anyway, I believe that you can get full functionality out of your CS4237B sound chip, even
under the standard Lenny kernel, if you read my web site carefully. It won't happen
automatically. But with the right configuration steps, it can be done.
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