[alsa-devel] embedded sound architecture question

Joachim Förster mls.JOFT at gmx.de
Fri May 11 17:21:05 CEST 2007

On Wed, 2007-05-09 at 14:20 -0700, John L. Utz III wrote:
> On Wed, 09 May 2007 22:47:34 +0200
> "Joachim Förster" <mls.JOFT at gmx.de> wrote:
> > My question is: Does the architecture described below make sense/is
> > reasonable with ALSA and Linux?
> i think you might have to answer an earlier question first; 'does it
> make sense to call this an ac97 controller?' I dont recall seeing a
> ring buffer as part of the ac97 standard. i'd suggest that you take the
> time to flesh out completely how the ring buffer is supposed to replace
> dma and ram while still presenting an ac97 set of verbs because i am
> stuck with the gut feeling that you will some important things will
> have to be really different.

Hmmm, well is there a standard document for AC97 controllers, too? So
far, I know about the AC97 Codec standard, only. Anyway, just ignore the
"AC97" in front of "controller" - a custom controller for an AC97 Codec,
which uses the described way of operation and features. The/My question
is, if such a thing is reasonable and fits into ALSA/Linux.

> > I read, that many applications don't work, if MMAP mode is not
> > supported and classic read/write (copy()/silence()) is used, only. Is
> > there a black list of apps, which don't work?
> i doubt seriously that such a thing exists, how could it? new apps are
> written everyday, old apps in binary only form get 'shimmed' forward
> with comaptibility libraries to work in newer operating systems.

So, not using MMAP mode is just a no-go ... ? I don't want to write a
driver which cannot be used with most ALSA applications out there.


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