Re: [Alsa-devel] Re: RFC: OSS driver removal, a slightly different approach

From: Takashi Iwai
Date: Fri Jan 20 2006 - 05:11:58 EST


At Thu, 19 Jan 2006 22:09:33 +0000,
Alan Cox wrote:
>
> On Iau, 2006-01-19 at 14:01 -0500, Lee Revell wrote:
> > > > Hmm. From sound/oss/kahlua.c:
> > > >
> > > > /*
> > > > * Initialisation code for Cyrix/NatSemi VSA1 softaudio
> > > > *
> > > > * (C) Copyright 2003 Red Hat Inc <alan@xxxxxxxxxx>
> > > > *
> > > >
> > > > Why was a new OSS driver written and accepted at such a late date, when
> > > > OSS was already deprecated?
> > >
> > > You'll find out that it must be pretty easy to write kahlua driver for
> > > ALSA, too, if you look at kahlua.c. Just need a hardware to certify
> > > if this is really demanded...
> >
> > Yes, it looks simple enough to write a driver without the hardware, as
> > long as someone volunteers to test it...
>
> Most of the Kahlua logic is in the SB driver. It was a wrapper added
> later to make autoconfiguration simple for end users. CS55x0 (VSA1
> variants) are generic sound blaster 16 emulation via SMI traps. There
> are certain things you must not do
>
> 1. Use a 64K or 128K in 16bit ring buffer
> 2. Disable/Enable DMA on the sound channel while audio is running
>
> #1 causes the box to hang dead (firmware emulation bug)
> #2 mistakenly flushes the FIFOs so breaks up the audio
>
> Otherwise its SB16 compatible.

Thanks for good hints.

BTW, I remember that there was a driver for native geode audio support
at the time of ALSA 0.5.x or earlier. I must have the code somewhere
in my storage. The porting would be much much harder than kaulha (sb
emulation), though.


Takashi
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