I started to experience this same issue with Ubuntu 16.04. I performed an apt upgrade and after rebooting I did not have any sound from my HDMI port. I did some research and I think I figured out why my Ubuntu 16.04 machine would not output audio on an HDMI port. I believe this is the same issue the original poster was experiencing.
There was a patch added to the kernel on 20 May 2019: https://lore.kernel.org/lkml/20190520115249.532929...@linuxfoundation.org/ My understanding is that sometimes HDMI ports where reported as plugged in even though they were not. To fix this the patch added a line of code that takes into account the eld_valid value along with the monitor_present value located at /proc/asound/cardX/eld#N.M. When I cat /proc/asound/card1/eld* I see monitor_present is 1 but eld_valid is 0 so this new line of code in hdmi_present_sense_via_verbs() will set jack->pin_sense to 0 instead of AC_PINSENSE_PRESENCE. That must cause the HDMI audio to appear unplugged. I further tested this theory by booting kernel 4.15.0-50 and now my HDMI audio works. If I boot back to 4.15.0-54 the HDMI audio reports unplugged and I do not get any audio on the HDMI cable. My understanding is that a video driver is responsible for setting eld_valid and my Radeon driver must not be doing that. So either the patch needs to be undone or the video drivers need to be patched. Otherwise we cannot use any kernels after 4.15.0-50. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1834771 Title: No HDMI-audio after kernel 4.15.-0.50 Status in linux package in Ubuntu: Confirmed Bug description: I've got no HDMI-audio. Latest kernel with working HDMI-audio is 4.15.-0.50. In pavucontrol HDMI-audio shows unplugged. And also internal audio shows unplugged, but it still works. I'm on linux mint 18.3. --- ApportVersion: 2.20.1-0ubuntu2.18 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: jouni 1859 F.... pulseaudio /dev/snd/controlC1: jouni 1859 F.... pulseaudio CurrentDesktop: X-Cinnamon DistroRelease: Linux 18.3 HibernationDevice: RESUME=UUID=9e8d7bf3-dc5f-4c72-b875-6dbe81a36c36 InstallationDate: Installed on 2017-01-28 (883 days ago) InstallationMedia: Linux Mint 18.1 "Serena" - Release amd64 20161213 IwConfig: lo no wireless extensions. enp3s0 no wireless extensions. MachineType: Gigabyte Technology Co., Ltd. To be filled by O.E.M. Package: linux (not installed) ProcFB: 0 amdgpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-54-generic root=UUID=f167a2b0-3b30-4a5a-907f-6b97c95b7a91 ro quiet iommu=soft splash vt.handoff=7 ProcVersionSignature: Ubuntu 4.15.0-54.58~16.04.1-generic 4.15.18 RelatedPackageVersions: linux-restricted-modules-4.15.0-54-generic N/A linux-backports-modules-4.15.0-54-generic N/A linux-firmware 1.157.21 RfKill: Tags: sylvia Uname: Linux 4.15.0-54-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo video _MarkForUpload: True dmi.bios.date: 02/26/2016 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: FC dmi.board.asset.tag: To be filled by O.E.M. dmi.board.name: 970A-UD3P dmi.board.vendor: Gigabyte Technology Co., Ltd. dmi.board.version: x.x dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 3 dmi.chassis.vendor: Gigabyte Technology Co., Ltd. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrFC:bd02/26/2016:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rn970A-UD3P:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.: dmi.product.family: To be filled by O.E.M. dmi.product.name: To be filled by O.E.M. dmi.product.version: To be filled by O.E.M. dmi.sys.vendor: Gigabyte Technology Co., Ltd. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1834771/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp