help understanding sound/snd_hda on mac pro w/ -STABLE.

George Hartzell hartzell at
Sun Sep 7 22:33:40 UTC 2008

I'm running -STABLE on a mac pro (deskside, not a macbook laptop).
With the stock snd_hda I have to set a hint that sets gpio1 get get
sound, and it's very quiet even at maximum volume.

I've been testing Alexander Motin's snd_hda patches.  With the patch
from 20080812 and by setting a hint that sets gpio1 I get great sound
from line-out.

With all of the later patches I've been unable to get sound from
line-out or the headphone jack.  If I set gpio0 I can get sound from
the tinny little internal speaker but that's it.

Various dmesg-verbose and /dev/sndstat output is available at:

Alexander had suggested that I should try other sound devices and I
thought I'd been trying them, but lately I'm not so sure.

/dev/sndstat reports pcm[0123] and I have /dev/mixer[0123].  I also
have a variety of /dev/dsp* entries, sometimes /dev/dsp0.0, sometimes
/dev/dsp0.1 and then /dev/dsp[123].0.  It seems like the dsp devices
get created on demand.

I've been trying to test the other devices using the -a switch to
mpg123, e.g. 'mpg123 -a /dev/dsp1.0 foo.mp3', but I just noticed that
no matter what device I specify, lsof shows that I'm using

I've tried from the console and from my gnome desktop with X running
via startx.

I've looked in the sound section of the handbook and it didn't clarify
anything for me.

Can someone explain (or even just discuss) how the various pcm devices
relate to /dev/mixer[0-4] (a simple 1:1 mapping?), the /dev/dsp
devices, my physical connectors, and the various thingies that snd_hda
reports via verbose boot and/or pindump?

An even simpler question would be, how can I test the other pcm



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