Modesetting driver cannot handle different display resolutions for two monitors

[Rocko]

I have an external 1920x1080 monitor attached to my laptop, which has a 3840x2160 display. When I run them both at their native resolutions, the laptop display only works in the top quarter of the desktop, except for the unity launcher and unity top bar. Anything that leaves the top quarter leaves trails and flickers awfully (see attached image, which shows everything except the flickering).

I also tried it with the laptop on 2560x1440 (I had to add it manually because of a a separate bug where the modesetting driver limits the max vertical refresh frequency of default modelines to 60 Hz) and exactly the same thing happens (although the geometry isn't one quarter any more).

It works fine with the intel driver, but not the modesetting driver, so it seems to be an xserver issue rather than a unity issue. It also works fine if I set both monitors to 1920x1080.

The modesetting driver seems to struggle with setting resolutions. When I first log into the desktop, it takes a good 5 seconds longer than the intel driver to set up the screens, and for a while it looks like I have a 640x480 screen (judging by the huge mouse pointer I get). Given this bug and the vertical refresh bug, maybe yakkety shouldn't default to the modesetting driver?

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: xserver-xorg 1:7.7+13ubuntu3
Uname: Linux 4.7.2-040702-generic x86_64
.tmp.unity_support_test.0:

ApportVersion: 2.20.3-0ubuntu7
Architecture: amd64
BootLog:

CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
CurrentDesktop: Unity
Date: Tue Aug 30 19:26:06 2016
DistUpgraded: 2016-07-25 02:38:44,004 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: yakkety
DistroVariant: ubuntu
DkmsStatus:
 bbswitch, 0.8, 4.4.0-9136-generic, x86_64: installed
 bbswitch, 0.8, 4.7.2-040702-generic, x86_64: installed
 nvidia, 367-367.44, 4.4.0-9136-generic, x86_64: installed
 nvidia, 367-367.44, 4.7.2-040702-generic, x86_64: installed
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation HD Graphics 530 [8086:191b] (rev 06) (prog-if 00 [VGA controller])
   Subsystem: Dell HD Graphics 530 [1028:06e4]
InstallationDate: Installed on 2016-07-04 (57 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
JournalErrors:
 Error: command ['journalctl', '-b', '--priority=warning', '--lines=1000'] failed with exit code 1: Hint: You are currently not seeing messages from other users and the system.
       Users in the 'systemd-journal' group can see all messages. Pass -q to
       turn off this notice.
 No journal files were opened due to insufficient permissions.
MachineType: Dell Inc. XPS 15 9550
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.7.2-040702-generic root=UUID=8de7ebec-48db-48b6-9eb9-fafdee4eb7d6 ro rootflags=subvol=@ quiet splash nogpumanager vt.handoff=7
SourcePackage: xorg
UpgradeStatus: Upgraded to yakkety on 2016-07-24 (36 days ago)
dmi.bios.date: 04/07/2016
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 01.02.00
dmi.board.name: 0N7TVV
dmi.board.vendor: Dell Inc.
dmi.board.version: A01
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr01.02.00:bd04/07/2016:svnDellInc.:pnXPS159550:pvr:rvnDellInc.:rn0N7TVV:rvrA01:cvnDellInc.:ct9:cvr:
dmi.product.name: XPS 15 9550
dmi.sys.vendor: Dell Inc.
version.compiz: compiz 1:0.9.13.0+16.10.20160818.2-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.70-1
version.libgl1-mesa-dri: libgl1-mesa-dri 12.0.1-3ubuntu2
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 12.0.1-3ubuntu2
version.xserver-xorg-core: xserver-xorg-core 2:1.18.4-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.10.2-1ubuntu1
version.xserver-xorg-video-ati: xserver-xorg-video-ati N/A
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20160706-1ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau N/A

[Joakim Koed (vooze)]

Can also confirm this on Lenovo X1 carbon (2015) with newest BIOS. It starts "flickering" and will often freeze after some time.

[penalvch (penalvch)]

Joakim Koed, it will help immensely if you filed a new report with Ubuntu by ensuring you have the package xdiagnose installed, and that you click the Yes button for attaching additional debugging information running the following from a terminal:
ubuntu-bug xorg

Also, please feel free to subscribe me to it.

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

[Rocko (rockorequin)]

The output of those commands are: 1.2.13 and 08/08/2016.

I can't test the same configuration that I originally tested for another week, but on another 1680x1050 monitor it did work, eventually. I had to restart lightdm several times because things happened like the mouse click no longer working, once when I changed the resolution it flipped everything sideways, and the mouse started moving extraordinarily slowly and the desktop was unusable.

My issue is that there's a more severe bug with the brightness control after resume in the newer BIOS and its predecessor, so I can't use it (see http://en.community.dell.com/techcenter/os-applications/f/4613/p/19985875/20927410#20927410). Dell's official response is that they are aware of it, but they clearly aren't fixing it since they have released a second BIOS with the same bug.

If it's purely a BIOS issue, why does the modeset driver have this screen resolution problem and not the intel driver?

[penalvch (penalvch)]

Rocko, to clarify, did this issue not occur in a release prior to Yakkety?

[Rocko (rockorequin)]

No, the issue didn't occur in Xenial, which defaults to the intel driver. (The intel driver doesn't have these issues.)

Just to be clear - it is possible that the issue is resolved with the later BIOS, but I won't know until I can test the known bad configuration again. (Unfortunately, I can't use the later BIOS full-time thanks to the brightness issue.)

In general, the modesetting driver works fine (and it doesn't tear on the external display when scrolling, unlike the intel driver, which is nice). Modesetting does struggle a bit when changing resolutions, and X slows down for a while after the resolution changes. It usually speeds back up within say 10 seconds, but sometimes the slowdown persists.

[penalvch (penalvch)]

Rocko, in order to allow additional upstream developers to examine the issue, at your earliest convenience, could you please test the latest upstream kernel available from http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D ? Please keep in mind the following:
1) The one to test is at the very top line at the top of the page (not the daily folder).
2) The release names are irrelevant.
3) The folder time stamps aren't indicative of when the kernel actually was released upstream.
4) Install instructions are available at https://wiki.ubuntu.com/Kernel/MainlineBuilds .

If testing on your main install would be inconvenient, one may:
1) Install Ubuntu to a different partition and then test this there.
2) Backup, or clone the primary install.

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, and Y are the first two numbers of the kernel version, and Z is the release candidate number if it exists.

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.

Also, you don't need to apport-collect further unless specifically requested to do so.

It is most helpful that after testing of the latest upstream kernel is complete, you mark this report Status Confirmed.

Lastly, to keep this issue relevant to upstream, please continue to test the latest mainline kernel as it becomes available.

Thank you for your help.

[Launchpad Janitor (janitor)]

[Expired for xorg (Ubuntu) because there has been no activity for 60 days.]