[pulseaudio-discuss] [PATCH] alsa-mixer: Don't let "Mic Jack Mode" alone create a "Line In" path

David Henningsson david.henningsson at canonical.com
Wed Oct 17 06:51:46 PDT 2012

On 10/17/2012 03:21 PM, Tanu Kaskinen wrote:
> On Wed, 2012-10-17 at 14:55 +0200, David Henningsson wrote:
>> Yes, setting "Mic Jack Mode" to "Line" would turn of the VREF pin of the
>> codec, i e, the phantom power to the microphone. In "Mic" mode there's
>> usually a phantom power of 80% of Vdd. (I have never actually measured
>> this - I'm just looking at the HDA spec.)
>> So my argument is more about confusion ("Hey, PulseAudio says I've got a
>> line in port, but I don't have one, let's file a bug!").
> Which scenario do you mean:
> 1) The user complains, because he sees a line-in port even though
> nothing is plugged in

That's the current situation.

> or
> 2) The user complains, because he sees a line-in port even though the
> the connector has only a mic symbol, and not a combined mic & line-in
> symbol?

The user complains because he sees *both* a line-in port and a mic port, 
even though he only has one port (with a mic symbol on it).

> If you mean scenario 1, do you agree that having two ports would be
> better, if both get marked unavailable when nothing is plugged in? (It's
> probably not so easy to write the code to implement that, and if I had
> to choose between the one-port solution and no solution at all, I'd
> choose the one-port solution.)

I'm a bit hesitant myself about which one is better; have two ports 
showing up at plug in, or just the mic one.

Also, it is not very difficult to write a new path or two to cover this 
specific scenario, but I'm also starting to feel that the model for 
paths is starting to get difficulties to scale.

David Henningsson, Canonical Ltd.

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