Arch Linux

73616c616e

Member

Registered: 2022-02-05

Posts: 1

Microphone LED is always on in the Thinkpad X1 Carbon

Hi!

The microphone LED is all the time enabled, either it's pressed or not. Function itself works and mute/unmute microphone. It started after upgrade to 5.13 kernel version.
The same bug is discussed and even solved here (but for me it didn't work) https://bugzilla.kernel.org/show_bug.cgi?id=213851

My current kernel version is 5.16.5-arch1-1. Of course I could have just run

echo 0 | sudo tee /sys/class/leds/platform\:\:micmute/brightness

but it's only a workaround and it's tiresome. Events also aren't shown for microphone switch (for others like disable audio etc. works) when running

amixer -c0 events

Last edited by 73616c616e (2022-02-05 06:53:32)

tonttu

Member

Registered: 2023-11-12

Posts: 6

Re: Microphone LED is always on in the Thinkpad X1 Carbon

Same problem. Thinkpad T14 (gen2 AMD). Latest Arch, everything updated.

The button works, the LED just stays always on. I would be happy with the LED being always off.

another

Member

Registered: 2023-11-26

Posts: 4

Re: Microphone LED is always on in the Thinkpad X1 Carbon

Same problem. Thinkpad T14 (gen2 AMD). Latest Arch, everything updated.

The button works, the LED just stays always on. I would be happy with the LED being always off.

To turn it always off...

# echo off > /sys/class/sound/ctl-led/mic/mode

... should do the trick.

To change the trigger, figure out the card id (e.g. through alsamixer, amixer, ...).
In my case the card id is 1 though that might differ on your hardware.

# cat /sys/devices/virtual/sound/ctl-led/mic/card1/list

See which switch has which id. For example:

# amixer -c1 controls
[...]
numid=18,iface=MIXER,name='Mic ACP LED Capture Switch'
numid=7,iface=MIXER,name='Capture Switch'
[...]

Check which one works by watching some of the mixers and pressing the button, e.g.

# watch -n1 -d 'amixer -c1 cget numid=18; amixer -c1 cget numid=7'

Detach what doesn't work:

# echo 'Capture Switch' > /sys/devices/virtual/sound/ctl-led/mic/card1/detach

Attach what does:

# echo 'Mic ACP LED Capture Switch' > /sys/devices/virtual/sound/ctl-led/mic/card1/attach

Persist it with systemd-tmpfiles or a service.

Last edited by another (2023-11-26 09:34:02)