Comment 17 for bug 776964

Believe I have discovered core problem for this ; the pin caps for pin 0x17 (rear mic input) need to have PIN_VREF80 set for the input to work. VREF50 and VREF100 also seem to work, but this does not seem to be the convention in the driver, all VREF values are 80. HIZ and GRD do not work.

This is not done by default, or when switching inputs.

Comparing the patch_analog.c source from maverick and natty ..

possible candidate for change

ad1988_auto_init_analog_input

A conditional has changed that sets PIN_VREF80 | PIN_IN ; does this actually need to send both verbs, because we are initializing an input?

It puzzles me, because the rest of the code looks like it's setting it correctly, but I don't grok it that well yet.