[pulseaudio-discuss] [PATCH 4/4] alsa-mixer: Add "Headphone Mic" support for 3-pin ASUS netbooks

[Raymond Yau]

2012-7-13 下午10:31 於 "David Henningsson" <david.henningsson at canonical.com>
寫道：
>
> On 06/28/2012 10:47 PM, David Henningsson wrote:
>>
>> On 06/28/2012 06:44 PM, Tanu Kaskinen wrote:
>>>
>>> On Thu, 2012-06-28 at 16:27 +0200, David Henningsson wrote:
>>>>
>>>> Some ASUS netbooks, such as the 1015 CX, have only one 3.5 mm jack,
>>>> but it can be used either as a headphone or as a mic (but not both
>>>> simultaneously).
>>>>
>>>> This patch adds support for the "Headphone Mic" path that is used
>>>> on these devices, so that we can use the jack as an external mic, and
>>>> doing so without muting the speaker.
>>>>
>>>> BugLink: https://bugs.launchpad.net/bugs/1018262
>>>> Signed-off-by: David Henningsson <david.henningsson at canonical.com>
>>>
>>>
>>> The patch looks good to me, but I have a question: with this "Headphone
>>> Mic", will the associated input and output paths always have "unknown"
>>> as the availability state when there's something plugged in?
>>
>>
>> "Unknown" when it is plugged in, and "no" when it is unplugged. Maybe I
>> should add the state.unplugged as well for clarity.
>>
>>> Does alsa
>>> provide any means to figure out which one actually is being used, and if
>>> so, what are we missing in pulseaudio to make this work better?
>>
>>
>> There's no autodetection by the hardware of what has been plugged in.
>>
>> The way it's implemented in ALSA is that there is a "Input Source" kctl,
>> and if you set it to "Headphone Mic" the jack retasks as mic, and if you
>> set it to "Internal Mic", the jack retasks as headphone.

but there is no input source control when there are one or two input
sources(auto-mic) and the driver does not create "ext mic boost" for node
0x1a

>>
>> In Windows 7, there is a popup when you plug in asking "Hey, what did
>> you plug in?" and you select Headphone or Mic manually that way. I guess
>> that would provide some extra level of elegance, but at least having a
>> way of using the external mic would be good enough for me at this point.

is it possible to create a switch to retask the jack as hp or mic since the
user should be able to do this without pulseaaudio ?
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