Page 1 of 1

Audio ACPI interface is read-only; can't unmute

Posted: Tue Sep 13, 2011 9:19 am
by Zak
I have a W500 running Ubuntu 11.04 with Linux 2.6.38. I want to be able to unmute the ACPI volume control from software because I'm using it as an alarm clock and it is necessary to be able to disable all forms of muting for this to be reliable.

From dmesg:

Code: Select all

[   30.299776] thinkpad_acpi: Console audio control enabled, mode: monitor (read only)
[ 5737.170493] thinkpad_acpi: Console audio control in monitor mode, changes are not allowed.
Attempting to write to /proc/acpi/ibm/volume produces "write error: Operation not permitted".

Re: Audio ACPI interface is read-only; can't unmute

Posted: Tue Sep 13, 2011 5:00 pm
by Mike42
http://www.thinkwiki.org/wiki/Thinkpad-acpi says:
As of kernel 2.6.33 the thinkpad_acpi driver now has a ALSA sub-driver which creates an additional ALSA volume control which represents the volume and mute buttons on the ThinkPad keyboard. Unfortunately no further integration exists at this point with userspace, such as PulseAudio and as such there is no effective change for the end-user
Looks like you have to load the thinkpad-acpi module with volume_control=1 to make an `amixer -D hw:29 set Console unmute` work. On my system I also had to do a `amixer set Master unmute` because the master channel got muted too.

Re: Audio ACPI interface is read-only; can't unmute

Posted: Wed Sep 14, 2011 4:09 am
by Zak
That fixed it. Thanks.