Re: ibook sound, limping mixer

Conrad H Ziesler wrote:

in case this is of any use to anyone:

Yes, I'm very interested. Since I actually started looking into the
specs and sources, but did not find the time to start coding the same.

it all seems simple enough.  i hacked up a simple i2c driver merged into
the mixer code from above, cut apart dmasound to eliminate the mixer
device and extraneous stuff,

can you send me a patch?

and added the appropriate missing
KL1_AUDIO_XXX and KL1_I2S_) bits to arch/ppc/kernel/feature.c (in
feature_bits_keylargo[], under FEATURE_Sound_xxx  so the daca gets powered
up)

then i rebooted and had sound and a mixer device, and was able to
hear some sound, fiddle with the mixer controls, and then hear no sound
once or twice i was able to reenable sound by randomly fiddling with the
mixer.

so apparently SOME data was getting across the i2c bus to the daca chip,
but probably it was reading trash.

Hmm. I first thought it might be an byte order issue but then realized
it would only swap left and right volume. No idea yet. I'll give it a
try myself later.

since the dac3550a has write-only i2c registers, its pretty hard to debug
the i2c interface.  probably if someone puts an oscilloscope probe on the
i2c bus signals it should all become clear.

I would recommend a logic analyzer or better an i2c analyzer. I have an
oscilloscope but I would not dare to try reading i2c signals by hand.

Christof


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