Microphone Through TRRS Jack Not Detected in Windows

The problem has been around for quite some time now, i.e., since the so-called TRRS jacks were introduced in MacBooks. In these, a single 3.5 mm jack connector is used to combine a stereo pair OUT with a mono microphone IN.

People are frustrated by the fact that the microphone on their headset is properly detected in OS X, but not in Windows/Bootcamp.

It appears that the problem stems from Microsoft's HDAudio.sys driver:

http://msdn.microsoft.com/en-us/library/windows/hardware/jj123860.aspx#jack

The workaround mentioned in the article above does not work due to the particular way the TRRS jack and the audio chip (cs4206, cs4207 and cs4208) are wired in the MacBooks: only a single jack detection event is possible, and if one is detected, a value is set in the chip, which reports the presence of a microphone. In this configuration, HDAudio.sys sees only one detection event associated with the headphones, and there is no way a second event associated with the microphone can be triggered physically.

So, it would seem that Microsoft has to rectify the way their HDAudio.sys behaves with respect to these TRRS jacks.

That being said, Apple provides a driver for the cs420x chips in their BootCamp packages. Assuming that it reads the status of the audio chip and transmits both the jack detection event and the associated values to the HDAudio.sys driver, it should be possible for the BootCamp driver to emulate those two trigger events slightly spaced in time that HDAudio.sys needs for now.

Does anyone know whether Apple, Microsoft, or both, are working on this particular issue?