bugDoudouLinux - Bugs: bug #16892, screen resolution 1280*1024...

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bug #16892: screen resolution 1280*1024 unavailable

Submitted by:  Sergey <ipitgpu>
Submitted on:  Tue Oct 19 03:54:47 2010  
Category: User interfaceSeverity: 4 - Important
Priority: 7 - HighStatus: Need Info
Privacy: PublicAssigned to: Jean-Michel Philippe <jmphilippe>
Open/Closed: OpenRelease: None

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Sat Nov 27 12:47:49 2010, comment #18:

I confirm that your monitor is not detected as an LCD and does not support 70Hz at 1280*1024. I have no solution right now.

Indeed I read the xresprobe script and it guesses CRT/LCD screen only using the existence of a digital video input. But many old LCD screen don't have this entry. Maybe we could use an additional guess based on screen width÷height ratio. It is 4/3 for CRT and often anything else for LCD. Of course some older LCD screen may also have a 4/3 ratio…

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Thu Nov 25 10:18:12 2010, comment #17:

I think there is also a potential mistake in Xorg configuration. I limited horizontal sync to the range 70-75 so it may happen that some screen do not fit at all. I should switch to a larger range, for example 70-90.

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Wed Nov 24 05:30:26 2010, comment #16:

I tried at another PC with the same monitor and result is positive.
It is really annoying but the problem is wider - we cannot predict how the system will look like at the most known PC configurations because we do not have a testing scenario and thus cannot run it!
I submitted hw report from this positive PC. Will be able to do the same from my PC in an hour (virus attack).

Sergey <ipitgpu>
Project Member
Tue Nov 23 08:37:00 2010, comment #15:

I think the problem is that your monitor is not detected as an LCD monitor and it does not support a 70Hz refresh rate at 1280×1024 (a limit which is added for CRT monitors not to blink). Could you please send me the hardware report for your configuration using the new tool in “Settings → System”? If you're connected to the Internet you'll be able to post the report directly to Gna.

NB: is it really annoying to have 1152×864 instead of 1280×1024?

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Tue Nov 23 06:43:40 2010, comment #14:

Not exactly.
Screen 0: minimum 320 x 200, current 1152 x 864, maximum 1152 x 1152
VGA-0 connected 1152x864+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
1152x864 75.0*
1024x768 74.9 70.1
832x624 74.6
800x600 72.2 75.0 74.9
640x480 75.0 72.8 75.0 74.8
720x400 70.1

Sergey <ipitgpu>
Project Member
Thu Nov 4 15:23:36 2010, comment #13:

More and more strange, your Xorg.conf looks good, it has the following line:

Modes "1280x1024" "1152x864" "1024x768" "800x600" "640x480" "400x300" "320x240"

Could you type the following command in the console to list all available resolutions:

$ xrandr

You should get something like this:

$ xrandr
Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 1680 x 1680
VGA connected 1680x1050+0+0 (normal left inverted right x axis y axis) 474mm x 296mm
1680x1050 60.0*+ 60.0 60.0*
1600x1200 60.0 59.9
1600x1024 60.0
1400x1050 74.8 70.0 60.0 60.0
1280x1024 75.0 59.9 60.0
1440x900 60.2 59.9
1280x960 60.0 59.9

Maybe 1280x1024 is not available at a refreshing rate greater than 70 Hz?

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Mon Nov 1 07:02:58 2010, comment #12:

Here it is again

(file #11041)

Sergey <ipitgpu>
Project Member
Fri Oct 29 10:55:57 2010, comment #11:

Strange, could you send your file “/etc/X11/xorg.conf”?

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Fri Oct 29 05:34:16 2010, comment #10:

Does not fixed in 28/10/2010 build

Sergey <ipitgpu>
Project Member
Mon Oct 25 05:23:52 2010, comment #9:


Sergey <ipitgpu>
Project Member
Fri Oct 22 11:58:22 2010, comment #8:

I'll change the limit in next Russian build I'll upload within days and you'll tell me, it's simpler!

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Fri Oct 22 04:06:52 2010, comment #7:

this one does not work again

Sergey <ipitgpu>
Project Member
Thu Oct 21 08:13:00 2010, comment #6:

Ok my command line was wrong, I used the multiply character instead of the X character… Try this command instead, which looks identical but is not:

$ sudo sed -i 's/"1152x864"/"1280x1024" "1152x864"/' /etc/X11/xorg.conf

It should lead you to 1280×1024. If it succeeds, please tell what you think about the size of the icons on the desktop and the empty space left. When I had 1600×1200 on my CRT they were very small and there was a lot of empty space.

Another alternative to solve the issue is to remove screen resolution limit and patch lxlauncher to have it change the icon size relatively to screen size (but lxpanel icons cannot be enlarged without being patched too I think). Honestly I have strictly no idea of the difficulty of this task.

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Wed Oct 20 11:30:55 2010, comment #5:

Could you send me your file “/etc/X11/xorg.conf”? I would like to check if resolution is written inside or not.

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Wed Oct 20 09:34:09 2010, comment #4:

I did it and this produce no results

Sergey <ipitgpu>
Project Member
Wed Oct 20 08:39:47 2010, comment #3:

OK I think your LCD screen is not detected as an LCD screen. I've already seen this happening. Indeed I added screen resolution limits because X server defaults to use the largest detected one (I think that's what Qimo does). So at home on my 19" CRT, it uses a very high 1600×1280 resolution which make icons and text very small. Currently the algorithm I added is quite simple:

if LCD detected
use native resolution
if monitor/card supports vertical refresh ≥ 70 Hz
force the use of a vertical refresh ≥ 70 Hz
add resolutions ≤ 1152×864

The test against vertical refresh frequency permits to avoid screen blinking, which tires eyes (this gives me headaches). In the future we could replace the static 1152×864 limit with a computation of physical screen resolution (dot/inch) but trials are required to find how undetected LCD displays can get their native resolution from computation…

As a workaround, if you feel that most Russian people have LCD screen, it is possible to remove the resolution limit or to increase it to 1280×1024, at least on the Russian version. You can test it on a running DoudouLinux system. Type the following in the console:

$ sudo sed -i 's/"1152×864"/"1280×1024" "1152×864"/' /etc/X11/xorg.conf

Then press Ctrl+Alt+Backspace or close the session to restart X.

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Wed Oct 20 02:18:51 2010, comment #2:

I use LCD as the most people in Russia.
I checked Qimo 2.0 Desktop OS for kids and it deals with 1280*1024 fine

Sergey <ipitgpu>
Project Member
Tue Oct 19 10:17:53 2010, comment #1:

What kind of monitor do you have, CRT, LCD?

DoudouLinux tries to set a resolution below 1152×864 for CRT screens because the interface is to small on higher resolutions. On the contrary on LCD screens it should let the system use the native LCD resolution whatever it is because it would otherwise lead to a blurring effect. But sometimes LCD detection does not work…

Jean-Michel Philippe <jmphilippe>
Project AdministratorIn charge of this item.
Tue Oct 19 03:54:47 2010, original submission:

Max screen resolution 1152*864 produce not good picture at my 19 inches monitor. The best for my monitor is 1280*1024 which is absent in a list of available resolutions

Sergey <ipitgpu>
Project Member


Attached Files
file #11041:  xorg.conf added by ipitgpu (2kB - application/octet-stream)
file #10852:  xorg.conf added by ipitgpu (1kB - application/octet-stream - xorg.conf file is attached)


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -unavailable- added by jmphilippe (Posted a comment)
  • -unavailable- added by ipitgpu (Submitted the item)

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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Thu Nov 4 15:23:36 2010jmphilippeStatusConfirmed=>Need Info
    Mon Nov 1 07:02:58 2010ipitgpuAttached File-=>Added xorg.conf, #11041
    Thu Oct 21 07:03:32 2010ipitgpuAttached File-=>Added xorg.conf, #10852
    Wed Oct 20 10:07:03 2010ipitgpuStatusNeed Info=>Confirmed
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