Comment 0 for bug 1477587

One display turns off when both outputs are set to 1920x1080@60.0. They both still work separately on that rate.
Forcing the one to "1920x1080@59.9" is functioning as a work-around.

The good kernel version was linux_3.19.0-21.21.
This Problem occurred in kernel linux_3.19.0-22.22 and linux_3.19.0-23.24.

GPU is: Radeon HD 6670 using the radeon open source driver.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: linux-image-3.19.0-23-generic 3.19.0-23.24
ProcVersionSignature: Ubuntu 3.19.0-23.24-generic 3.19.8-ckt2
Uname: Linux 3.19.0-23-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: andreas 3695 F.... pulseaudio
 /dev/snd/controlC1: andreas 3695 F.... pulseaudio
CurrentDesktop: Unity
Date: Thu Jul 23 15:12:26 2015
HibernationDevice: RESUME=UUID=4f0d7a88-5c8d-41c5-a44c-d195a257fd4e
InstallationDate: Installed on 2012-04-11 (1198 days ago)
InstallationMedia: Xubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
IwConfig:
 eth0 no wireless extensions.

 lo no wireless extensions.
MachineType: Dell Inc. OptiPlex 755
ProcFB: 0 radeondrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.19.0-23-generic root=UUID=4acbdc21-f685-460d-a0dc-f86e6f346bf3 ro plymouth:debug splash quiet drm.debug=0xe
RelatedPackageVersions:
 linux-restricted-modules-3.19.0-23-generic N/A
 linux-backports-modules-3.19.0-23-generic N/A
 linux-firmware 1.143.2
RfKill:

SourcePackage: linux
UpgradeStatus: Upgraded to vivid on 2015-04-27 (87 days ago)
dmi.bios.date: 04/30/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A10
dmi.board.name: 0GM819
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 6
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA10:bd04/30/2008:svnDellInc.:pnOptiPlex755:pvr:rvnDellInc.:rn0GM819:rvr:cvnDellInc.:ct6:cvr:
dmi.product.name: OptiPlex 755
dmi.sys.vendor: Dell Inc.