Bug 33286 - gnome-display-properties / randr incorrectly detects XGA VGA projectors as 1360x768
Summary: gnome-display-properties / randr incorrectly detects XGA VGA projectors as 13...
Status: NEW
Alias: None
Product: xorg
Classification: Unclassified
Component: Server/General (show other bugs)
Version: 7.5 (2009.10)
Hardware: x86 (IA32) Linux (All)
: medium normal
Assignee: Xorg Project Team
QA Contact: Xorg Project Team
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-01-19 20:25 UTC by Jean-François Fortin Tam
Modified: 2011-03-08 10:36 UTC (History)
0 users

See Also:
i915 platform:
i915 features:


Attachments
xorg log (61.08 KB, text/plain)
2011-01-20 08:31 UTC, Jean-François Fortin Tam
no flags Details

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Description Jean-François Fortin Tam 2011-01-19 20:25:28 UTC
With gnome-display-properties, projectors' maximum resolution is incorrectly detected as 1360x768 instead of 1024x768. Since university/conference projectors are pretty much all XGA projectors, it doesn't seem to make sense that they would support resolutions higher than 1024x768.

Notes:
- I've had this problem for years with every projector I've encountered in universities/conferences
- This is over a VGA connection
- I had this problem on Intel i915 GPUs and I'm seeing this now on my T43p sporting a M24GL [Mobility FireGL V3200] running the open source radeon driver
- This problem doesn't occur with LCD monitors (or TVs) over VGA

I was wondering initially if this might be related to the VGA cable (those projectors must have pretty long extension cables, maybe it messes up autodetection). In any case, the user/presenter can't change the wiring of the building, and I wonder where it actually picks that 1360x768 from, anyway.

I've tried to find similar bug reports but they're either very old or with different symptoms, so sorry if it has already been reported.
Comment 1 Alex Deucher 2011-01-19 22:58:13 UTC
Please attach your xorg log.  I'm pretty sure this is an xserver issue.  The projectors most likely do not provide an edid so the default modes are added and the xserver picks 1360x768.  This patch may fix the issue:
http://lists.freedesktop.org/archives/xorg-devel/2010-November/015410.html
Comment 2 Jean-François Fortin Tam 2011-01-20 08:31:39 UTC
Created attachment 42231 [details]
xorg log


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