Microphone Mute Button

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General

Some Thinkpads come with a Microphone Mute Button possibly with an led.

It does not work on Ubuntu, a bug has been reported and a patch has been proposed: https://bugs.launchpad.net/ubuntu/+source/udev/+bug/408903

If you don't have /sys/devices/platform/thinkpad_acpi/leds/tpacpi::micmute, you'll need to patch your kernel with this patch.

Workaround using acpid

Pressing the mic mute button will generate a acpi event

$ acpi_listen
button/micmute MICMUTE 00000080 00000000 K

Depending on your model and your version of acpid it may generate a different event

$ acpi_listen
ibm/hotkey HKEY 00000080 0000101b

add a acpid rule to handle this event in /etc/acpi/events/lenovo-mutemic:

event=button/micmute MICMUTE 00000080 00000000 K
action=/etc/acpi/lenovo-mutemic.sh

the script (/etc/acpi/lenovo-mutemic.sh) to toggle the mice look like this:

#!/bin/bash

led="/sys/devices/platform/thinkpad_acpi/leds/tpacpi::micmute/brightness"
user=$(who | awk '/0\.0/{print $1; exit;}')
[[ -z $user ]] && user=root
if [[ $(amixer sget Capture) == *"[on]"* ]]; then
  logger "Microphone is now muted (for $user) $USER"
  amixer sset Capture nocap
  [[ -f $led ]] && echo 1 > $led
  sudo -u $user DISPLAY=":0.0" notify-send -i microphone-sensitivity-muted-symbolic "Microphone" "Microphone is now <b>MUTED</b>"
else
  logger "Microphone is now on (for $user)"
  amixer sset Capture cap
  [[ -f $led ]] && echo 0 > $led
  sudo -u $user DISPLAY=":0.0" notify-send -i microphone-sensitivity-high-symbolic "Microphone" "Microphone is now <b>ON</b>"
fi

Explanation:

  • led contain the path to the led in the mute button (see below)
  • user is the name of the user, which is currently signed in in X11 and notify-send will send a notification to that user. Remove these lines if you don't like it.
  • Pressing the button will toggle the state of the ALSA capture device, which is maybe not optimal in all cases as it disables all capture devices. Mic would be another choice, but on some thinkpads it is named Internal Mic.

ALSA will not remember the state of the led at startup, so one need another small start-up script:

#!/bin/bash

led="/sys/devices/platform/thinkpad_acpi/leds/tpacpi::micmute/brightness"
if [[ $(amixer sget Capture) == *"[off]"* ]]; then
  [[ -f $led ]] && echo 1 > $led
fi

and put it in /etc/local.d/lenovo-mutemic.sh.

F20

If you have a recent version of udev/systemd (see this patch) the acpi trick will not work. The mic mute button will be mapped to F20 (keycode 190), which you should be able to configure normally using the GNOME keyboard settings or similar.

The ACPI mapping is defined in /lib/udev/keymaps/module-lenovo, there you can see if 0x1A is mapped to micmute or F20.

Needed for models

T410, T410s, X230

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