1002:68a0 After suspend-resume graphics are sluggish and input lags with displayport connected

[Michiel Janssens]

After resuming from suspend-to-ram, graphics on displayport connected Dell U2415 monitor are sluggish and input has lag.
Examples:
- transition from unity greeter login locked status to unlocked status: 6 seconds (normal 1 second)
- transition from clicking dash and getting window: 2-3 seconds (normal <1 second)
- starting gedit: 4 seconds (normal <1 second)
- mouse lags, sometimes the pointer is still on the left side of the screen, while it should be on the right
- input from keyboard lags, about 1-2 seconds (normal no lag)

When unplugging the Displayport cable all lag is gone.

When plugging displayport back in again lag is back, same as before.

After a reboot, response of graphics and input is normal. So two options to get rid of the lag: unplug DP or reboot.

Further investigation:
Did a mainline kernel bisect:
From 3.13.11-ckt27 (good) to v4.3-wily (bad)
First bad is v4.0-rc1-vivid
Did a kernel commit bisect:
From 3.19 (good) to 4.0-rc1 (bad)
first bad commit: [e55bca26188e45f209597abf986c87cc5a49894a] radeon/audio: enable DP audio

Commit bisect log is attached

WORKAROUND: radeon.audio=0
However, I'm not able to use audio over Displayport.

ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: linux-image-4.2.0-18-generic 4.2.0-18.22
ProcVersionSignature: Ubuntu 4.2.0-18.22-generic 4.2.3
Uname: Linux 4.2.0-18-generic x86_64
ApportVersion: 2.19.1-0ubuntu4
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: michiel 1788 F.... pulseaudio
 /dev/snd/controlC1: michiel 1788 F.... pulseaudio
CurrentDesktop: Unity
Date: Thu Nov 12 22:08:27 2015
HibernationDevice: RESUME=UUID=d0de679a-8c90-4a25-a84a-8d3c25eb0a10
InstallationDate: Installed on 2015-10-31 (12 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
MachineType: Hewlett-Packard HP EliteBook 8740w
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/@wily/boot/vmlinuz-4.2.0-18-generic root=UUID=f16430cd-a447-4cf2-8f8b-ce233e03d462 ro rootflags=subvol=@wily quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.2.0-18-generic N/A
 linux-backports-modules-4.2.0-18-generic N/A
 linux-firmware 1.149.1
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: 07/07/2014
dmi.bios.vendor: Hewlett-Packard
dmi.bios.version: 68CAD Ver. F.50
dmi.board.name: 1520
dmi.board.vendor: Hewlett-Packard
dmi.board.version: KBC Version 33.31
dmi.chassis.asset.tag: CNU1152Q9W
dmi.chassis.type: 10
dmi.chassis.vendor: Hewlett-Packard
dmi.modalias: dmi:bvnHewlett-Packard:bvr68CADVer.F.50:bd07/07/2014:svnHewlett-Packard:pnHPEliteBook8740w:pvr:rvnHewlett-Packard:rn1520:rvrKBCVersion33.31:cvnHewlett-Packard:ct10:cvr:
dmi.product.name: HP EliteBook 8740w
dmi.sys.vendor: Hewlett-Packard

[Michiel Janssens (janssensm)]

Added commit bisect log

[Brad Figg (brad-figg)]

This change was made by a bot.

[penalvch (penalvch)]

Michiel Janssens, thank you for reporting this and helping make Ubuntu better.

Could you please test the latest upstream kernel available from the very top line at the top of the page from http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D (the release names are irrelevant for testing, and please do not test the daily folder)? Install instructions are available at https://wiki.ubuntu.com/Kernel/MainlineBuilds . This will allow additional upstream developers to examine the issue.

If the latest kernel did not allow you to test to the issue (ex. you couldn't boot into the OS) please make a comment in your report about this, and continue to test the next most recent kernel version until you can test to the issue. Once you've tested the upstream kernel, please comment on which kernel version specifically you tested. If this issue is fixed in the mainline kernel, please add the following tags by clicking on the yellow circle with a black pencil icon, next to the word Tags, located at the bottom of the report description:
kernel-fixed-upstream
kernel-fixed-upstream-X.Y-rcZ

Where X, Y, and Z are numbers corresponding to the kernel version.

If the mainline kernel does not fix the issue, please add the following tags:
kernel-bug-exists-upstream
kernel-bug-exists-upstream-X.Y-rcZ

Please note, an error to install the kernel does not fit the criteria of kernel-bug-exists-upstream.

Once testing of the latest upstream kernel is complete, please mark this report's Status as Confirmed. Please let us know your results.

Thank you for your understanding.

[Michiel Janssens (janssensm)]

Tested with latest mainline kernel 4.3, the issue exists.

[penalvch (penalvch)]

Michiel Janssens, 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 (TO Slava Grigorev, Alex Deucher, and Christian König CC dri-devel)?

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.

[Michiel Janssens (janssensm)]

Before reporting upstream I tested some further.
Narrowed it down a little bit:
The issue only happens when displayport is connected to Dell U2415 (wether or not connected to an extra monitor (vga)).
When connected to displayport only on Dell U2412M the issue does not appear.
So the issue is related to U2415 with displayport, or a DP v1.2 capable monitor.
U2412M is only DP v1.1 capable.
Still no workaround. Daisy chaining is not posible because the graphics card is only DP v1.1 capable.
I will report upstream now.

[Michiel Janssens (janssensm)]

Direct URL to dri-devel mailinglist:
http://marc.info/?l=dri-devel&m=144780894513907

[Michiel Janssens (janssensm)]

Workaround:

Adding kernel parameter radeon.audio=0 resolves the issue.
However with that setting, not able to use audio over Displayport in that case off course

[penalvch (penalvch)]

Michiel Janssens, given you haven't heard anything on the list, feel free to post this bug to https://bugs.freedesktop.org/enter_bug.cgi?product=xorg&component=Driver/Radeon .

[Michiel Janssens (janssensm)]

Bug report:
https://bugs.freedesktop.org/show_bug.cgi?id=93073