Ubuntu

Sound stops working after suspend to RAM

Asked by Torsten Jerzembeck

Hi everyone,

the update from Edgy to Feisty on my HP Compaq nx5000 laptop went smoothly. However I just noticed a rather strange phenomenon: After I suspend the laptop (to RAM) and wake it up again, the sound output stays mute.

The ALSA system thinks that everything's fine, and applications using the sound system (xmms, for example) don't notice anything wrong, but the speakers stay silent. I checked with alsamixer, and it reports nothing as muted. Changing the controls ans muting/unmuting all possible channels doesn't have an effect, either. The only way to solve this problem is to reboot the machine, which makes the sound system work again (until the next suspend, that is). I haven't tried to unload and load again the alsa modules, as I haven't had the nerve to fiddle with the dependencies on unload.

I suspect that there is something wrong with the ACPI implementation, but do not know how to verify this.

Is there any way short of rebooting to make the sound system work again after a suspend-resume cycle?

Greetings from Stuttgart,

=ToJe=

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wvengen (wvengen) said : 		#1

You can easily remove a module with all its dependencies by using "modprobe -r some-module". I'd suggest to indeed try unloading/reloading your sound module (assuming you know what your sound driver module is, if not just ask). Removing a module only works if nothing is using your soundcard; you may need to close sound applications and remove your volume-control applet from Ubuntu's (by default: top) bar.

If this makes your soundcard work again, you could add this module to MODULES in the file /etc/default/acpi-support to automatically unload/reload it with suspending. That, again, would only work when no application is using your sound device while suspending.

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Torsten Jerzembeck (toje) said : 		#2

I experimented a bit with the sound modules. Even after removing and reloading everything that looked like a sound module (everything named snd_*, plus soundcore and ac97_bus), the sound system stays mute after a suspend. All applications using the sound system seem to work fine, with the exception that they don't produce any sound, of course.

I suspect I should open a bug report for this, but against wich package?

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wvengen (wvengen) said : 		#3

Too bad it didn't work. I'd open a bug for alsa-driver ( https://launchpad.net/ubuntu/feisty/+source/alsa-driver ). Please mention the alsa driver your hardware uses (probabely the topmost item in `lsmod | grep snd`, the one with some reference to your sound hardware, like snd_hda_intel).
Oh, I assume you have checked your volume controls and switches, right? Sometimes they aren't restored properly after a suspend/resume cycle. Try to fiddle with every possible control related to sound output, so the hardware is set again. (Then again, reloading the module probably has the same effect.)

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