ASUS ROG STRIX X870-F GAMING WIFI (ALC4080, USB ID 0b05:1b9b): Rear Mic-In detected as Line Input under Linux

[GitHub issues - opened <github@alsa-project.org>]

alsa-project/alsa-ucm-conf issue #780 was opened from PoMpls:

Hardware:

* Motherboard: ASUS ROG STRIX X870-F GAMING WIFI
* Audio Codec: Realtek ALC4080 (USB Audio)
* USB Audio ID: 0b05:1b9b

Software:

* Debian 13 (Trixie)
* Kernel: 6.12.90-amd64
* alsa-ucm-conf: 1.2.14
* PipeWire: 1.4.2

Issue:

The rear microphone input (Mic-In) does not work under Linux, while it works correctly under Windows using the same hardware and cable.

The motherboard rear audio panel only provides:

* Mic In
* Line Out
* Optical S/PDIF Out

There is no physical rear Line-In connector.

However, ALSA reports:

Mic - Input Jack  : off
Line - Input Jack : on

when a microphone is connected to the rear Mic-In port.

Observed behavior:

* Rear Mic-In does not capture any audio.
* arecord receives no signal.
* Discord cannot receive audio from the rear microphone.
* Front panel microphone works correctly.
* When the microphone is connected to the front panel header, ALSA reports:

Mic - Input Jack : on

and audio capture works normally.

Diagnostic information:

amixer reports:

Analog In - Input Jack : on
Line - Input Jack      : on
Mic - Input Jack       : off

The USB mixer exposes:

Unit 9  -> Analog In - Input Jack
Unit 11 -> Line - Input Jack
Unit 12 -> Mic - Input Jack

Current UCM profile:

ProfileName "Realtek/ALC4080"

TThe board is currently matched by the generic ALC4080 profile.

USB ID 0b05:1b9b is documented in USB-Audio.conf as:

"ASUS ROG STRIX X870E-E GAMING WIFI"

However the affected system is:

ASUS ROG STRIX X870-F GAMING WIFI

from:

/usr/share/alsa/ucm2/USB-Audio/USB-Audio.conf

Possible issue:

The motherboard appears to be using the generic ALC4080 profile. The rear Mic-In connector may be incorrectly mapped or detected as Line Input. Since the X870-F rear panel does not provide a Line-In connector, the reported "Line - Input Jack : on" state seems incorrect.

Could a board-specific quirk/profile be required for USB ID 0b05:1b9b or for the ASUS ROG STRIX X870-F GAMING WIFI?

Additional observation:

When a microphone is connected to the rear Mic-In connector:

Mic - Input Jack : off
Line - Input Jack : on

When the same microphone is connected to the front panel header:

Mic - Input Jack : on

and audio capture works correctly.

This suggests that the rear microphone jack detection may be incorrectly reported or mapped.

Issue URL     : https://github.com/alsa-project/alsa-ucm-conf/issues/780
Repository URL: https://github.com/alsa-project/alsa-ucm-conf