[Multimedia] Audio card disappears after low battery forced sleep

[cfaber]

So I just had my xps 13 9370 running the latest updates force sleep due to low power mode, when the laptop was woken back up again only the dummy audio device was present. Ideas?

[GreyGeek]

Use lshw or lspci to find out the kind of audio chip you have. From that info you can search for the module (*.ko) that is loaded at boot up. Then you can "modprobe somemodule.ko" to get your sound back.

Hint: Coming back from the sleep mode is problematic. I set my box to power down on low power.

[cfaber]

It's not coming back from sleep mode that's the problem. I can sleep/wake this thing many times without issue. It seems to be something else going on in which the laptop is forced to sleep when the battery is critically low. Additionally the devices were present and all modules loaded, maybe something wrong with the audio server <-> plasma interface?

[vinnywright]

So I just had my xps 13 9370 running the latest updates force sleep due to low power mode,

did those "updates" finish or were they still running when it went to sleep ?

VINNY

[GreyGeek]

Suspend puts the computer to sleep by saving system state in RAM. In this state the computer goes into a low power mode, but the system still requires power to keep the data in RAM. To be clear, Suspend does not turn off your computer. That means that if your computer is already low on power and you've set it to suspend, it will more than likely shut down while in the suspend mode and the info in RAM will be lost.

A relative of mine was dual booting with Windows and Kubuntu and put her computer into the Suspend mode and shut the lid. She thought it was off. It wasn't. She unplugged it and the battery drained. When she tried to turn it on the next day it tried to restore Kubuntu but couldn't. She brought it to me for recovery. (Sorry, I don''t remember what I did, but it probably involved running the recovery option on grub somehow.)

Hibernate is a bit of a deeper sleep. Hibernate mode moves the current contents of memory into swap space. In this state the computer does not require power. To be clear, the computer is completely powered off with Hibernate. IF you don't have a swap space, or don't have sufficient swap space (2X your RAM) then Hibernate won't work.

Moral: Don't use Suspend or Hibernate. When you are don't using your machine power it down. Sip some tea while those 2 minutes of boot up tick off.