snd-powermac @ G4 DA (PowerMac3, 4) - headphone detection doesn't work

snd-powermac @ G4 DA (PowerMac3, 4) - headphone detection doesn't work

[Douglas Mencken]

I can hear sound with internal speakers only if I plug headphones
jack, without plugged jack, there's no sound at all; to listen thru
headphones, I need to half-insert that jack and this leads to
distortions; with h/phones jack plugged fully, no sound in phones, but
sound in internal speaker. With the same half-plug, in OS X I head
sound both via h/phones and internal speaker.
Driver: snd-powermac. Audio card: Tumbler @ i2ca @ KeyLargo i2c (I can
provide the full dump of OpenFirmware device tree).

As <gnubien> at #alsa @ irc.freenode.net suggested, I ran `alsamixer
-c 0` and MM-ed 'Auto Mute'. After that, I can fully plug h/phones
jack and enjoy full sounds w/o distortions but still can't get any
sound when it's unplugged.

The result of running ./alsa-info.sh:
Your ALSA information is located at
http://www.alsa-project.org/db/?f=daac9e06cbe772222b90d7fba14c1a49a65b980c

Re: snd-powermac @ G4 DA (PowerMac3, 4) - headphone detection doesn't work

[Risto Suominen]

Sounds strange. MM-ing 'Auto Mute' would mean disabling it, so
plugging anything should have no effect.

You could try running alsamixer while plugging in the headphones. This
should be instantly visible: 'Headphone Detection' MM -> OO, 'PC
Speaker' OO -> MM. (when 'Auto Mute' OO)

On my iMac G4 800 MHz, with Tumbler audio and ALSA driver 1.0.22.1,
everything works with snd-powermac.

Risto