Bug 216818 - The microphone mute led not working after linux 6
Summary: The microphone mute led not working after linux 6
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: Sound(ALSA) (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: Jaroslav Kysela
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-12-18 08:52 UTC by sonic82003
Modified: 2022-12-19 17:08 UTC (History)
1 user (show)

See Also:
Kernel Version: >= 6.0
Tree: Mainline
Subsystem:
Regression: No


Attachments

Description sonic82003 2022-12-18 08:52:32 UTC
The mic mute led of my ThinkPad X1 Carbon Gen 9 doesn't work anymore after updating linux to version 6.
I can still turn it on by  running 

echo 1 > /sys/class/leds/platform::micmute/brightness

With linux-lts it still works fine.
Comment 1 Hans de Goede 2022-12-19 09:58:13 UTC
This is caused by a behavior change of the kernel code controlling the LED to only turn on the LED when all inputs, including e.g. the jack mic input are turned off in the alsa-mixer settings.

But most userspace code only turns the mic which it is actually using on/off when you hit the mic-mute hotkey.

Also see: https://bugzilla.redhat.com/show_bug.cgi?id=2134824

Which is the same bug.

There is a set of fixes available in the form of an alsa-ucm update which tells the kernel to ignore the state of the jack mic input restoring the old behavior:

https://git.alsa-project.org/?p=alsa-ucm-conf.git;a=commitdiff;h=79a8ec44d3dcf097f4a4492c506cbcf338324175
https://git.alsa-project.org/?p=alsa-ucm-conf.git;a=commitdiff;h=9ce9ddb4a84fb467602b716575ea1d8f2bab0c39
Comment 2 Jaroslav Kysela 2022-12-19 17:08:25 UTC
The easy way is to ask your distro to update the UCM configuration to the recent one.

Note that all previous kernels have a bug which may cause that the microphone LED is not updated correctly with the sof-hda-dsp driver. Just plug something to the analog jack on your system and mute/unmute/mute the analog input. The microphone LED will follow those changes, too. So you cannot trust the state for the old kernels anyway.

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