GPU lockup when using 2 video cards

[Rena Kunisaki]

My system has a Radeon HD 7750 and Radeon HD 6450, together driving 4 displays:
Left: VGA on 7750 via DisplayPort adaptor, 1280x1024
Middle: DVI on 7750, 1920x1080
Right: HDMI on 7750, 1680x1050
Top (above Middle): VGA on 6450, 1280x1024

With only Left, Middle and Right enabled, everything works fine. When I try to enable the top display by running:
$ xrandr --output VGA-1-0 --above DVI-0 --mode 1280x1024
then the top screen only displays noise, and the entire system will lock up for about 10 seconds at a time, then run again for 10 seconds (and the top screen goes blank), then lock up again, repeating until the top screen is disabled again. syslog and kern.log report one of the GPUs is locking up.

With the proprietary driver fglrx, I can run all 4 displays, but it requires the use of Xinerama, so I have no RandR or compositing, which stinks. With the open source driver RandR and compositing work fine.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: xserver-xorg-video-ati 1:7.2.0-0ubuntu10
ProcVersionSignature: Ubuntu 3.11.0-12.19-generic 3.11.3
Uname: Linux 3.11.0-12-generic x86_64
ApportVersion: 2.12.5-0ubuntu2
Architecture: amd64
Date: Tue Oct 22 12:59:19 2013
InstallationDate: Installed on 2013-10-22 (0 days ago)
InstallationMedia: Lubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MarkForUpload: True
SourcePackage: xserver-xorg-video-ati
UpgradeStatus: No upgrade log present (probably fresh install)

[Rena Kunisaki (i-am-inuyasha)]

Further research: when attempting to place the "top" screen in any other position (left, right, or below other displays), it displays the same noise, but the system doesn't hang. Syslog and kern.log are spammed with a new message:

Oct 22 13:08:28 guilmon kernel: [ 1105.381816] radeon 0000:02:00.0: couldn't schedule ib
Oct 22 13:08:28 guilmon kernel: [ 1105.381824] [drm:radeon_cs_ib_chunk] *ERROR* Failed to schedule IB !

[penalvch (penalvch)]

HyperHacker, this bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? If so, could you please test for this with the latest development release of Ubuntu? ISO images are available from http://cdimage.ubuntu.com/daily-live/current/ .

If it remains an issue, could you please run the following command in the development release from a Terminal (Applications->Accessories->Terminal), as it will automatically gather and attach updated debug information to this report:

apport-collect -p xserver-xorg-video-ati REPLACE-WITH-BUG-NUMBER

Please note, given that the information from the prior release is already available, doing this on a release prior to the development one would not be helpful.

Thank you for your understanding.

Helpful bug reporting tips:
https://wiki.ubuntu.com/ReportingBugs

[Rena Kunisaki (i-am-inuyasha)]

I've tried this driver again, and this time it was only able to detect one screen. I'll try with a development version next time I reboot.

[Launchpad Janitor (janitor)]

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