Monitor prefs: poor resolution options when EDID fails

Bug #769366 reported by Dylan Justice on 2011-04-23
This bug affects 1 person
Affects Status Importance Assigned to Milestone
gnome-control-center (Ubuntu)

Bug Description

Binary package hint: gnome-control-center

If EDID/DDC fails, the resolution options are too restrictive; an exhaustive list of resolutions should be available.

Use case: I run my third monitor through a DisplayPort-->DVI adapter, so no EDID information is returned. I cannot find any way to set the correct resolution short of generating an xorg.conf.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic-pae
Uname: Linux 2.6.38-8-generic-pae i686
NonfreeKernelModules: fglrx
Architecture: i386
CompizPlugins: [core,bailer,detection,composite,opengl,decor,mousepoll,vpswitch,regex,animation,snap,expo,move,compiztoolbox,place,grid,imgpng,gnomecompat,wall,ezoom,workarounds,staticswitcher,resize,fade,unitymtgrabhandles,scale,session,unityshell]
CompositorRunning: compiz
Date: Fri Apr 22 23:42:38 2011
DistUpgraded: Fresh install
DistroCodename: natty
DistroVariant: ubuntu
 virtualbox-ose, 4.0.4, 2.6.38-8-generic-pae, i686: installed
 fglrx, 8.840, 2.6.38-8-generic-pae, i686: installed
 ATI Technologies Inc Cypress [Radeon HD 5800 Series] [1002:6899] (prog-if 00 [VGA controller])
   Subsystem: Hightech Information System Ltd. Device [1787:2290]
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Beta i386 (20110413)
JockeyStatus: xorg:fglrx - ATI/AMD proprietary FGLRX graphics driver (Proprietary, Enabled, In use)
MachineType: Gigabyte Technology Co., Ltd. GA-890GPA-UD3H
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.38-8-generic-pae root=UUID=7bd4798d-7a99-4476-820d-843bf0d1ced4 ro quiet splash vt.handoff=7
Renderer: Unknown
SourcePackage: xserver-xorg-video-ati
UpgradeStatus: No upgrade log present (probably fresh install) 07/23/2010
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: FD GA-890GPA-UD3H
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrFD:bd07/23/2010:svnGigabyteTechnologyCo.,Ltd.:pnGA-890GPA-UD3H:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnGA-890GPA-UD3H:rvr:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr: GA-890GPA-UD3H
dmi.sys.vendor: Gigabyte Technology Co., Ltd.
version.compiz: compiz 1:0.9.4+bzr20110411-0ubuntu1
version.fglrx-installer: fglrx-installer N/A
version.libdrm2: libdrm2 2.4.23-1ubuntu6
version.libgl1-mesa-dri: libgl1-mesa-dri 7.10.2-0ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 7.10.2-0ubuntu1
version.xserver-xorg: xserver-xorg 1:7.6+4ubuntu3
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:6.14.0-0ubuntu4
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.14.0-4ubuntu7
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:0.0.16+git20110107+b795ca6e-0ubuntu7

Dylan Justice (dsjstc) wrote :
Changed in gnome-control-center (Ubuntu):
importance: Undecided → Low
Sebastien Bacher (seb128) wrote :

Thank you for taking the time to report this bug and helping to make Ubuntu better. Unfortunately, we cannot work on this bug because your description didn't include enough information. You may find it helpful to read "How to report bugs effectively" We'd be grateful if you would then provide a more complete description of the problem.

We have instructions on debugging some types of problems at

At a minimum, we need:
1. the specific steps or actions you took that caused you to encounter the problem,
2. the behavior you expected, and
3. the behavior you actually encountered (in as much detail as possible).

Changed in gnome-control-center (Ubuntu):
status: New → Incomplete
Dylan Justice (dsjstc) wrote :

The bug is that when no EDID information is available, the default resolution options top out at 1024x768. This is not usable on most modern systems. It would be very easy to provide a list of standard 4:3 and 16:9 resolutions so that if it can't be autoconfigured, a user can at least use the gui to choose something *close* without having to generate an Xorg.conf.

To address the minimum criteria for a complete bug report, I reiterate from my initial post:

1) I created a system that used a DP->DVI adapter. No EDID info was generated.
2) I expected to be presented with a list of common resolutions in the gui.
3) The list of default resolutions topped out at 1024x768.

Launchpad Janitor (janitor) wrote :

[Expired for gnome-control-center (Ubuntu) because there has been no activity for 60 days.]

Changed in gnome-control-center (Ubuntu):
status: Incomplete → Expired
Bryce Harrington (bryce) wrote :

It's actually not as simple as that; resolutions are not just pluggable numbers, but are actually calculated from 'modelines' which describe the physical CRT or LCD drawing behaviors and refresh cycle rates which are fairly specific to a given piece of hardware.

So, you can't take a given 1280x800 modeline for a Sony CRT monitor and reuse it unchanged on a BENQ LCD flatscreen or a Fujitsu laptop; it's likely this would just result in a scrambled screen most of the time.

The only modelines which are *guaranteed* to work on any monitor are the ones specified by the VESA standard. Those are the modelines corresponding to 1024x768, 800x600, and 640x480 - the "poor resolution options" that you're being presented with. Ideally VESA would put out newer standards, however even if they did that wouldn't solve it for all the hw already out there.

One idea we've been pursuing to better address the case of EDID failures is to allow for saving and loading EDID blobs into the kernel. Then, you could either generate an EDID yourself through some sort of tool (e.g. perhaps deriving it from your monitor's setup cd), or save it off the monitor (or get it from someone with the same monitor), and then the system can load it at boot. This is already adequately covered by another bug report and the work is in progress (but no ETA on when it'll be available in the distro.)

Changed in gnome-control-center (Ubuntu):
status: Expired → Won't Fix
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