I've been running into this problem over and over again and found several different solutions. However, some of them also stopped working after installing updates. There is this solution that I found when using the NVIDIA proprietary drivers: http://askubuntu.com/a/511907/73753. Which involves suspending your laptop, to trick it into powering on the audio chip on your nvidia gpu.
However, I seriously recommend using the nouveau driver nowadays. As it supports the nvidia optimus technology, whereas the proprietary driver does not. Though, the drawback is that the nouveau driver only supports opengl 3.3. See http://nouveau.freedesktop.org/wiki/Optimus/. The difference is that you use `DRI_PRIME=1` instead of `optirun`. And that you use `echo DDIS > /sys/kernel/debug/vgaswitcheroo/switch` instead of `prime-select nvidia` before restarting X11 when you want to use the hdmi output. With nouveau, my hdmi audio still does not work out of the box. Though, the audio device is listed in lspci -H1 when booted, which saves us half the trouble we had with the NVIDIA driver. The steps I use to get the driver loaded for the audio device are (warning, this might hang your pc, also, if your pc fails to (re)boot, perform a hard-reset by removing the power & battery and waiting 3 or more minutes (1 minute is not sufficient)): - press ctrl+alt+f1 - login and run `sudo su` - shut down x11 and the loginscreen, such that the gpu is no longer in use. I could do that by running `runlevel` followed by `init 3` - 'remove' the gpu: `echo 1 > /sys/bus/pci/devices/0000\:01\:00.0/remove` - redetect the gpu: `echo 1 > /sys/bus/pci/rescan` - If everything went right, the driver for the hdmi audio chip should be loaded. Verify this by running `lscpi` and checking if there is a line like "01:00.1 Audio device: NVIDIA Corporation GF116 High Definition Audio Controller (rev a1)". - switch to the hdmi output: `echo DDIS > /sys/kernel/debug/vgaswitcheroo/switch` - start the login manager and x11 again: in my case I needed to run `init 5` where 5 was the number reported by `runlevel`. I obtained the remove & rescan pci trick from https://devtalk.nvidia.com/default/topic/609790/linux/no-hdmi-sound-w -optimus-in-linux/. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to alsa-driver in Ubuntu. https://bugs.launchpad.net/bugs/1377653 Title: HDMI sound output not detected / NVIDIA optimus laptop Status in alsa-driver package in Ubuntu: Confirmed Bug description: Hi, not sure if this is an alsa or nvidia/nouveau bug. HDMI audio output doesn't appear in sound settings output panel. Audio works well on internal speakers, but it seems there is no way to make it output to hdmi... The laptop has optimus NVIDIA+Intel. The behaviour is the same with nouveau or nvidia proprietary driver. Please let me know if further testing is required ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: alsa-base 1.0.25+dfsg-0ubuntu4 ProcVersionSignature: Ubuntu 3.13.0-36.63-generic 3.13.11.6 Uname: Linux 3.13.0-36-generic x86_64 NonfreeKernelModules: nvidia ApportVersion: 2.14.1-0ubuntu3.5 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: sam 2295 F.... pulseaudio CurrentDesktop: Unity CurrentDmesg: Error: command ['sh', '-c', 'dmesg | comm -13 --nocheck-order /var/log/dmesg -'] failed with exit code 1: comm: /var/log/dmesg: Permission denied Date: Sun Oct 5 17:05:35 2014 InstallationDate: Installed on 2014-04-21 (166 days ago) InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417) PackageArchitecture: all SourcePackage: alsa-driver Symptom: audio Title: PCI/internal sound card not detected UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/02/2012 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: N56VZ.215 dmi.board.asset.tag: ATN12345678901234567 dmi.board.name: N56VZ dmi.board.vendor: ASUSTeK COMPUTER INC. dmi.board.version: 1.0 dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: ASUSTeK COMPUTER INC. dmi.chassis.version: 1.0 dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrN56VZ.215:bd11/02/2012:svnASUSTeKCOMPUTERINC.:pnN56VZ:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnN56VZ:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0: dmi.product.name: N56VZ dmi.product.version: 1.0 dmi.sys.vendor: ASUSTeK COMPUTER INC. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1377653/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
