Xorg external LCD connected to laptop is not recognized

Latest response

I am using RHEL6 on a Lenovo T410.  The internal LCD is defaulting to 1024x768, but after I log in switches to 1280x800, which is correct.


My problem is I have an external LCD that is also connected to it.  It's an HP LE2201w that wants 1680x1050.  System-config identifies it as "Unknown" and will not allow beyond 1024x768.


Since it's a laptop that isn't always connected to the external LCD, I'm not sure if a manual xorg.conf is the way to go.


Any thoughts on how to fix this?


lspci: 00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02) (prog-if 00 [VGA controller])


Are you connecting the monitor via VGA or Displayport?  A colleague of mine is running RHEL 6 on his T410 and I asked him to check connecting it to an external monitor.  He connected via VGA and it displayed properly at 1280x1024.

If you are using Displayport it might be worthwhile to try VGA, if only just to see if the problem is specific to one or the other.  I'll admit I've never had a system that used Displayport so I'm not sure if there are any special steps to setting it up, but if we can say its specific to that then someone else might have some ideas on how to solve this problem

What does xrandr think the displays can do?


Mine reports this with two screens (Laptop is LVDS1 and external monitor is VGA1)


[mflitter@flits ~]$ xrandr
Screen 0: minimum 320 x 200, current 2330 x 1680, maximum 8192 x 8192
LVDS1 connected 1280x800+0+0 (normal left inverted right x axis y axis) 261mm x 163mm
   1280x800       60.0*+   59.8     59.9     50.0  
   1280x768       59.9     60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   848x480        60.0  
   640x480        59.9  
VGA1 connected 1050x1680+1280+0 right (normal left inverted right x axis y axis) 459mm x 296mm
   1680x1050      59.9*+
   1280x1024      75.0     60.0  
   1280x960       60.0  
   1152x864       75.0  
   1024x768       75.1     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)


To set my monitors up I use:


xrandr --output LVDS1 --mode 1280x800 --output VGA1 --mode 1680x1050 --rotate right

so your command would be something like:


xrandr --output <LAPTOP_OUT> --mode 1280x800 --output <EXTERNAL_OUT> --mode <MAX_RES_FROM_XRANDR>

Add --left-of <output> or --right-of <output> to set up screen positions and --rotate <left|right> at your pleasure if portrait screens are your thing!

I made mine works with external projector by following the idea from this site.


Hope it helps.