ICH6-M audio support for ASUS notebook

Dmitry Pryanishnikov dmitry at atlantis.dp.ua
Tue Nov 29 23:01:03 GMT 2005


On Tue, 8 Nov 2005, Dmitry Pryanishnikov wrote:
> I'm going to buy a notebook and trying to decide what chipset it should be
> built on. Vast majority of Intel-based Centrinos are built on 915GM + ICH6-M
> (Alviso) chipset. As I've read in datasheet ICH6-M contains two different
> sound engines: good old AC97 and new Intel's "High Definition audio"
> (which AFAIK isn't supported by our sound driver). Engines can't work 
> together, only one of them can be enabled. I know that our sound driver

  I'm replying to my own message in order to get this information recorded
(and to attract sound system developers attention). I've bought an ASUS M5A 
notebook, based on Intel 915GM + ICH6-M, and it _doesn't_ work with FreeBSD's
sound system. This notebook doesn't present AC97 audio device to the system,
it presents HDA instead. Moreover, it seems that this can't be changed by the
OS. I've found the chipset register (FD - Function Disable Register), which 
controls "disabled" status of different part of ICH6-M. Alas, Intel's 
document says:

 	When a function is disabled, software must not attempt to re-enable
 	it. A disabled function can only be re-enabled by a platform reset.

And it seems to be sad, but true: I've managed to clear bits in this
register, which disable AC97 audio (device 30 : function 2 of ICH6-M) and
AC97 modem (device 30 : function 3), and set bit which disables HDA
(device 27 : function 0). So yes, HDA registers have disappered.
And no, AC97 registers haven't appered.

   So it seems that at least on ASUS M5A there are no easy ways to use AC97
sound engine, and FreeBSD's sound driver must support Intel's HDA in
order to work on this platform.

Sincerely, Dmitry
Atlantis ISP, System Administrator
e-mail:  dmitry at atlantis.dp.ua
nic-hdl: LYNX-RIPE

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