Screen corruption after unblank with HWE stack

[Andrei Borzenkov]

After update of video drivers to HWE stack as per https://wiki.ubuntu.com/Kernel/LTSEnablementStack (sudo apt-get install --install-recommends xserver-xorg-hwe-16.04) I experience reproducible screen corruption after unblanking screen. What happens

- screen goes blank
- I move mouse, screen unblanks
- random parts of screen begin to blink rapidly. Forcing redraw of window content (e.g. by clicking on application window to raise it) stops blinking.

I never observed this issue when using GA versions of Xorg stack. Using HWE kernel as well.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: xserver-xorg-video-intel-hwe-16.04 2:2.99.917+git20160706-1ubuntu1~16.04.1
ProcVersionSignature: Ubuntu 4.8.0-36.36~16.04.1-generic 4.8.11
Uname: Linux 4.8.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
CurrentDesktop: Unity
Date: Sat Feb 18 08:39:21 2017
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-trusty-amd64-20140620-0
InstallationDate: Installed on 2015-07-02 (596 days ago)
InstallationMedia: Ubuntu 14.04 "Trusty" - Build amd64 LIVE Binary 20140620-04:25
SourcePackage: xserver-xorg-video-intel-hwe-16.04
UpgradeStatus: Upgraded to xenial on 2016-10-29 (111 days ago)

[Launchpad Janitor (janitor)]

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

[Andrei Borzenkov (arvidjaar-s)]

I noticed that Xorg is now using modesetting driver while in the past I think it was using Intel driver. How can I easily switch back to Intel for testing?

[Andrei Borzenkov (arvidjaar-s)]

After I observed visible tearing when watching video on external HDMI screen I switched back to Intel driver.

Before:

[ 34.531] (II) Loading /usr/lib/xorg/modules/drivers/modesetting_drv.so
[ 34.548] (II) Module modesetting: vendor="X.Org Foundation"
[ 34.548] compiled for 1.18.4, module version = 1.18.4
[ 34.548] Module class: X.Org Video Driver
[ 34.548] ABI class: X.Org Video Driver, version 20.0

After:

[ 36.090] (II) Loading /usr/lib/xorg/modules/drivers/intel_drv.so
[ 36.139] (II) Module intel: vendor="X.Org Foundation"
[ 36.139] compiled for 1.18.4, module version = 2.99.917
[ 36.139] Module class: X.Org Video Driver
[ 36.139] ABI class: X.Org Video Driver, version 20.0

This fixed both issue reported here and tearing during video playback.

[Timo Aaltonen (tjaalton)]

does it happen with current hwe xserver, which is based on 1.19.x?

[Andrei Borzenkov (arvidjaar-s)]

Yes, I still observed it under current HWE server 1.19 with modesetting driver. (I intentionally switched back from Intel to modesetting to test it). I did not see it recently though (without any X related updates), but what I see currently is - screen goes blank, I move mouse, screen unblanks and then after second or so quickly blanks/unblanks again. It looks as if some hardware re-probing happens.

It is possible that it is kernel related, there were some i915 fixes in kernel updates.

[Andrei Borzenkov (arvidjaar-s)]

> I did not see it recently though

Just yesterday I observed it again.

[Andrei Borzenkov (arvidjaar-s)]

Update: recently one of programs I use started to complain that screen was not DRI3 capable. I am using Intel driver which apparently defaults to DRI2. I forced it to DRI3 using

Option "DRI" "3"

After that I immediately got tearing during video and the same strange corruption of screen (fast blinking). As modesetting driver defaults to DRI3 it appears the issue is not Intel vs. modeseting but rather DRI2 vs. DRI3.

Googling around suggests that this may be this upstream bug:

https://bugs.freedesktop.org/show_bug.cgi?id=97957

If there is Ubuntu package for 16.04 that includes above commit I would be more than happy to test it.

[Andrei Borzenkov (arvidjaar-s)]

I tried to install mesa 17.2.4 (which should include this commit) from ppa ubuntu-x-swat, but still the same - as soon as I attempt to enable DRI3 I get screen corruption and tearing.

[Timo Aaltonen (tjaalton)]

16.04 is EOL, if you can reproduce on a newer release, please open a new bug, thanks