Radeon R9 380 HDMI, Digital Out -- No sound at all

[Zalethon]

Distro is Ubuntu Studio (lsb_release says 'Ubuntu 16.04 LTS')

HDMI audio output worked in 15.10. No sound after upgrade to 16.04.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 4.4.0-21.37-lowlatency 4.4.6
Uname: Linux 4.4.0-21-lowlatency x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: schuyler 1729 F.... pulseaudio
 /dev/snd/controlC1: schuyler 1729 F.... pulseaudio
CurrentDesktop: XFCE
Date: Mon Apr 25 17:24:09 2016
InstallationDate: Installed on 2016-02-28 (57 days ago)
InstallationMedia: Ubuntu-Studio 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:HDMI failed
Symptom_Card: Tonga HDMI Audio [Radeon R9 285/380] - HDA ATI HDMI
Symptom_DevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: schuyler 1729 F.... pulseaudio
 /dev/snd/controlC1: schuyler 1729 F.... pulseaudio
Symptom_Jack: Digital Out, HDMI
Symptom_Type: No sound at all
Title: [To be filled by O.E.M., ATI R6xx HDMI, Digital Out, HDMI] No sound at all
UpgradeStatus: Upgraded to xenial on 2016-04-25 (0 days ago)
dmi.bios.date: 07/27/2015
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: F2
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Z170-HD3P-CF
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: To Be Filled By O.E.M.
dmi.chassis.version: To Be Filled By O.E.M.
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF2:bd07/27/2015:svnGigabyteTechnologyCo.,Ltd.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnZ170-HD3P-CF:rvrx.x:cvnToBeFilledByO.E.M.:ct3:cvrToBeFilledByO.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.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[jose (r1esg0)]

Exact same graphic card.
Exact same behavior. Sound goes well with hdmi after flesh install of ubuntu 15.10 (after several years wanting it),
doesnt work anymore when I upgraded to 16.04.
Please fix.