Date: Wed, 15 Mar 2000 08:20:00 -0500 (EST) From: Chuck Robey <chuckr@picnic.mat.net> To: Seigo Tanimura <tanimura@r.dl.itc.u-tokyo.ac.jp> Cc: doconnor@gsoft.com.au, roger@cs.strath.ac.uk, freebsd-multimedia@FreeBSD.ORG, nsayer@quack.kfu.com Subject: Re: Understanding AC97 Message-ID: <Pine.BSF.4.21.0003150816270.32633-100000@picnic.mat.net> In-Reply-To: <14543.26674.980546.81928B@rina>
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On Wed, 15 Mar 2000, Seigo Tanimura wrote: > On Wed, 15 Mar 2000 19:32:31 +1030 (CST), > "Daniel O'Connor" <doconnor@gsoft.com.au> said: > > Daniel> On 15-Mar-00 Roger Hardiman wrote: > >> While AC97 is a standard, you still need > >> to know how to setup the chip which interfaces AC97 to your > >> ISA or PCI bus. > > Daniel> So conceviably you could have acbus0: a la miibus0: ? > > Not sure if the configuration will be like that in the future, but we > now drive AC97 in a unified way implemented in sys/dev/sound/pcm/ac97.c. > > It would be interesting to work out a method to determine if a chip > actually accompanies with an AC97 codec or some other one. Certain > onboard sound systems have a PCI sound chip and an ISA codec (eg > CS461x(PCI)-CS423x(ISA) and NeoMagic 256AV(PCI)-MSS(ISA)) to provide a > legacy interface as well. In most cases these ISA codecs are not compatible > with AC97, so the drivers need to handle them in a different way. The only specs I was able to find sugested that AC97 was a feature set only, and had nothing whatsoever to do with how a chip interfaced, or handled delivery of the features. If this is right (I wouldn't mind being corrected here) then the idea of a acbus0 seems a little strange, with no definition of what an acbus is. A "feature" being something like, delivery of stereo audio derived from an N bit codec, not how to get that data, or what binary format it takes. > > ---------------------------------------------------------------------------- Chuck Robey | Interests include C & Java programming, FreeBSD, chuckr@picnic.mat.net | electronics, communications, and signal processing. New Year's Resolution: I will not sphroxify gullible people into looking up fictitious words in the dictionary. ---------------------------------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message
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