On Mon, Oct 13, 2003 at 12:56:51PM -0400, Nathan J. Williams wrote:

> You're right that mixer control is the tricky issue. I believe all
> modern (white) iBooks use the Tumbler audio, as do newer G4 Powerbooks
> (the original G4 powerbook used the awacs driver somewhat
> successfully).

The original iBooks used a chip "officially" labeled DAC <somenumberhere>A, and 
referred to by Apple as DACA.

Most of the early new-world machines used the Screamer chip (the B&W G3, PCI G4,
and older iMacs are the notable exceptions).  So of course, I'd like to get my
hands on such a machine (or a DVD personality card for my Beige G3) to try
everything out.

Apple seems to have standardized on the Tumbler (some more-or-less off the shelf
TI chip) with a few machines using the so-called Snapper chip (similar TI chip).

The mixer code is pretty ugly, but what I've had the patience for so-far is just
fixed (max) volume output on my machine.  This works for the headphone out since
my speakers have a volume control on them... but this doesn't work so great for
the internal speaker.  Either way, this is much nicer than no sound.  I've got a
nearly ready to test copy of the code that implements similar support for those
odd-ball new-world machines as well.  If there's more interest in that, I could
probably churn something out by the end of the week.

I have a partial compilation that I've gleaned off of some OF dumps to back this
up, but I'm not sure how accurate they are.  How successful was 'somewhat'
successful with the G4 PowerBook?

Recording, if that's important to anyone, should be extremely trivial (just exec
the proper DBDMA command basically).

Unfortunately a lack of time, bootable kernels, disk space, and hardware has kept
me from accomplishing much more.

What's really worth keeping an eye on, IMO, is the bmac driver that will make its
way into FreeBSD/ppc.  Peter seems eager to de-suckify the performance problems
and "properly" newbusify the DBDMA stuff.  Oh I can hardly wait for >40kbytes/sec
w/ scp over the LAN.

- alex