Public bug reported:
## Problem
On an ASUS ExpertBook running Ubuntu 26.04, the hardware microphone mute
key works correctly, but the physical microphone-mute LED does not
automatically synchronize with the microphone mute state.
## Expected behaviour
When the microphone is muted using the ASUS hardware microphone-mute
key, the microphone mute LED should turn on.
When the microphone is unmuted, the LED should turn off.
## Actual behaviour
The microphone mute key itself works, but the LED does not automatically
change state together with the microphone mute state.
The LED hardware is functional because its state can be controlled
manually through the Linux LED sysfs interface.
The LED is exposed as:
`/sys/class/leds/platform::micmute`
Its brightness can be manually changed using:
`echo 1 | sudo tee /sys/class/leds/platform::micmute/brightness`
and:
`echo 0 | sudo tee /sys/class/leds/platform::micmute/brightness`
These commands physically turn the LED on and off respectively.
## Steps to reproduce
1. Boot Ubuntu 26.04 on the ASUS ExpertBook.
2. Log into the Ubuntu desktop.
3. Use the hardware microphone mute key.
4. Observe the microphone mute state.
5. Observe the physical microphone mute LED.
6. Repeat the operation to unmute the microphone.
7. Observe that the LED does not automatically synchronize with the mute state.
## Troubleshooting
* Confirmed the ASUS microphone mute key itself works.
* Confirmed `/sys/class/leds/platform::micmute` exists.
* Confirmed the LED has a brightness value of 0/1.
* Confirmed the physical LED can be turned on and off manually through sysfs.
* Confirmed the issue persists after reboot.
* The system is running the Ubuntu 26.04 kernel.
This appears to be an ASUS hardware/firmware integration issue involving
the Linux ASUS WMI/LED handling rather than a physically defective LED.
## Additional information
The Apport-generated kernel and hardware information is included with
this report.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-31-generic 7.0.0-31.31
ProcVersionSignature: Ubuntu 7.0.0-31.31-generic 7.0.14
Uname: Linux 7.0.0-31-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: kaveen-amarasekara 3309 F.... pipewire
kaveen-amarasekara 3325 F.... wireplumber
/dev/snd/seq: kaveen-amarasekara 3309 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sat Sep 19 17:02:56 2026
InstallationDate: Installed on 2026-09-18 (1 days ago)
InstallationMedia: Ubuntu 26.04.1 LTS "Resolute Raccoon" - Release amd64
(20260826)
MachineType: ASUSTeK COMPUTER INC. ASUS EXPERTBOOK B1502CBA_B1502CBA
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-31-generic
root=UUID=3a895c67-1e59-4435-b1d0-e347cf641da2 ro quiet splash
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No
PulseAudio daemon running, or not running as session daemon.
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/27/2026
dmi.bios.release: 5.26
dmi.bios.vendor: American Megatrends International, LLC.
dmi.bios.version: B1502CBA.317
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: B1502CBA
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: 1.0
dmi.ec.firmware.release: 17.2
dmi.modalias:
dmi:bvnAmericanMegatrendsInternational,LLC.:bvrB1502CBA.317:bd04/27/2026:br5.26:efr17.2:svnASUSTeKCOMPUTERINC.:pnASUSEXPERTBOOKB1502CBA_B1502CBA:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnB1502CBA:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:sku:pfaASUSEXPERTBOOK:
dmi.product.family: ASUS EXPERTBOOK
dmi.product.name: ASUS EXPERTBOOK B1502CBA_B1502CBA
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK COMPUTER INC.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
** Attachment added: "asus-mic-led.txt"
https://bugs.launchpad.net/bugs/2167766/+attachment/6001176/+files/asus-mic-led.txt
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https://bugs.launchpad.net/bugs/2167766
Title:
ASUS ExpertBook microphone mute key works but platform::micmute LED
does not synchronize with mute state
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