Sound output starts several seconds late using DisplayPort with [AMD/ATI] Tahiti XT HDMI Audio [Radeon HD 7970 Series] [1002:aaa0]

[Etienne URBAH]

I am using simultaneously :
- an audio headset connected to the analog audio output,
- a DisplayPort cable to connect my display to my 'AMD Tahiti XT [Radeon HD 7970 ...]' graphics + sound card.

Using the 'Sound' panel of 'gnome-control-center', I systematically get following behaviour for sound output :

- If I choose the 'Line Out - Built-in Audio' device, the sound output comes immediately :
   For example, inside the 'Test Speakers' window, the correct sound systematically starts as soon as I hit any 'Test' button (under 'Front Left' or 'Front Right').

- But if I choose the 'HDMI / DisplayPort - Tahiti XT HDMI Audio [Radeon HD 7970 Series]' device, the sound output starts several seconds LATE :
   For example, inside the 'Test Speakers' window, the sound starts at the end of the 2nd time I hit any 'Test' button (under 'Front Left' or 'Front Right'). Then continuous sound is correct and in sync.
   But after approx. 10s of silence (no sound to output), new sound output starts several seconds LATE again.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: linux-image-4.2.0-14-generic 4.2.0-14.16
ProcVersionSignature: Ubuntu 4.2.0-14.16-generic 4.2.2
Uname: Linux 4.2.0-14-generic x86_64
ApportVersion: 2.19-0ubuntu1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/pcmC0D0c: z_admin 1665 F...m pulseaudio
 /dev/snd/controlC0: z_admin 1665 F.... pulseaudio
 /dev/snd/controlC1: z_admin 1665 F.... pulseaudio
CurrentDesktop: GNOME
Date: Thu Oct 8 17:46:05 2015
HibernationDevice: RESUME=UUID=ccecc437-66d2-4e39-ac56-76ab11e18140
InstallationDate: Installed on 2015-09-27 (10 days ago)
InstallationMedia: Ubuntu-GNOME 15.10 "Wily Werewolf" - Alpha amd64 (20150924)
IwConfig:
 enp2s0 no wireless extensions.

 lo no wireless extensions.
MachineType: To be filled by O.E.M. To be filled by O.E.M.
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.2.0-14-generic root=UUID=a5c156d8-eac3-47fa-835c-b2c4ebda969d ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.2.0-14-generic N/A
 linux-backports-modules-4.2.0-14-generic N/A
 linux-firmware 1.149
RfKill:

SourcePackage: linux
UdevLog: Error: [Errno 2] No such file or directory: '/var/log/udev'
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/07/2014
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 2501
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: M5A97 R2.0
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev 1.xx
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.:bvr2501:bd04/07/2014:svnTobefilledbyO.E.M.:pnTobefilledbyO.E.M.:pvrTobefilledbyO.E.M.:rvnASUSTeKCOMPUTERINC.:rnM5A97R2.0:rvrRev1.xx: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: To be filled by O.E.M.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.3 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.3-rc4-unstable/

[Etienne URBAH (eurbah)]

This issue is also systematic using following kernel versions with parameter 'radeon.audio=1' :

- From Ubuntu Vivid (15.04) :
   All successive 3.19.0-x

- From http://kernel.ubuntu.com/~kernel-ppa/mainline :
   - 4.0.0-040000
   - 4.1.8-040108

[Etienne URBAH (eurbah)]

With kernel version 4.3.0-040300rc4, the issue stays essentially the same.

But the sound output now systematically starts at the BEGINNING of the 2nd time I hit any 'Test' button.

So, there seems to be a slight improvement.

[Etienne URBAH (eurbah)]

After updating the BIOS and the Linux Kernel, the issue stays completely the same.
So, I am trying to mark this report Status 'Confirmed'.

# dmidecode -t 0 | grep -E 'BIOS Information|Vendor|Version|Release'

BIOS Information
 Vendor: American Megatrends Inc.
 Version: 2603
 Release Date: 06/26/2015

# uname -r

4.3.0-040300rc5-generic

[Etienne URBAH (eurbah)]

With kernel 4.3.0-040300rc6, the issue stays completely the same.

[penalvch (penalvch)]

Etienne URBAH, the issue you are reporting is an upstream one. Could you please report this problem following the instructions verbatim at https://wiki.ubuntu.com/Bugs/Upstream/kernel to the appropriate venue (radeon at freedesktop)?

Please provide a direct URL to your newly made report when it becomes available so that it may be tracked.

Thank you for your understanding.

[Etienne URBAH (eurbah)]

I have reported this issue at https://bugs.freedesktop.org/show_bug.cgi?id=92889

[ralphb (dev-endlos)]

Same issue here. I just wanted to add that I'm using on-board Intel graphics.

[penalvch (penalvch)]

ralphb (dev-endlos), it will help immensely if you filed a new report with the Ubuntu via a terminal:
ubuntu-bug audio

Please feel free to subscribe me to it.

For more on why this is helpful, please see https://wiki.ubuntu.com/ReportingBugs.

[Etienne URBAH (eurbah)]

This issue seems to be NOT specific to AMD/ATI Tahiti XT :

For example, it has been reported with NVIDIA GTX 970 at https://askubuntu.com/questions/874320/audio-starts-playing-3-5-seconds-after-video-does

So, I suggest to report this issue at https://www.alsa-project.org (instead of 'radeon at freedesktop').

Besides, I suggest to change the title of this issue to the following more precise title :

Sound output using DisplayPort is NOT played during the first 3-5 seconds (on several audio hardware)