Comment 54 for bug 1252733

https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/sound/pci/hda/patch_realtek.c?id=73bdd597823e2231dc882577dbbaf8df92fe1775

the patch is for dell notebook, it may not work if you are using Asus notebook

it depend on how the notebook vendor and codec vendor implement the combo jack

e.g. 92HD91 datasheet mention that Mic jack is not supported on the combo jack

2.22.Combo Jack Detection 4 conductor (combo) jacks are becoming popular. In the most common implementation the 4 conductor plug has the same mechanical dimensions as a 3 conductor 3.5mm plug but the sleeve portion has been split into two segments:S1 and S2. When a 4-conductor plug (headset) is inserted into the jack T (Tip) = Left headphone audio, R (Ring) = Right headphone audio, S1 (First half of sleeve) = microphone input, and S2 (Second half of sleeve) = return (GND). When a 3-conductor plug (headphones) is inserted into the jack; T=Left audio, R=Right audio, S1=GND, S2=GND. By monitoring the S1 connection to see if it is shorted to ground, we can distinguish between headsets and headphones. Please note that analog microphone plugs (3-conductor-Lmic/Rmic/GND) and optical SPDIF plugs can not be supported using this implementation.