Re: Experimental USB audio support

[Takashi Iwai <tiwai@suse.de>]

At Fri, 31 May 2002 20:14:36 +0900,
Patrick Shirkey wrote:
> 
> Takashi Iwai wrote:
> > 
> > At Fri, 31 May 2002 11:41:46 +0200,
> > I wrote:
> > >
> > > > > > devfs: devfs_register(): device already registered: "unknown"
> > > > >
> > > > > this is a bug of sound_core.c.  you can fix it by replacing
> > > > > sound_core.c with the one in alsa-kernel tree.
> > > > >
> > > >
> > > > General question. Is the above likely to cause problems if I don't swap
> > > > them?
> > >
> > > no, it works fine on 2.4 kernel, too.  i'm using it.
> > 
> > err, my statement was not clear --
> > 
> 
> Yep :)
> 
> > original sound_core.c is ok as long as if you don't use devfs _and_
> > multiple cards.  the one in alsa-kernel is fixed for such a
> > condition.  but, generally, swapping to the fixed one will cause no
> > problem.  it's fully compatible.
> > 
> 
> So as long as I don't use devfs I don't need it. Currently I still use
> the /proc interface but I don't have concrete understanding of the
> difference between the two yet. fromwhat I gathered you have to specify
> devfs in the kernel for it to be used. Is that correct?

yes.  let me rephrase:

if you use devfs interface for /dev, you cannot use the 2nd or later
card with the original sound_core.c on 2.4 kernel.
if you use proc interface for /dev/snd, it works anyway.

also -

if you build the kernel with devfs support and use 2nd or later cards,
then you'll get annoying error messages, even if you use proc
interface.  (it's harmless, though.)


Takashi

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