linux mint MDM / Login Window Resolution Issue

[Aergan]

Also posted at Linux Mint forums but no response as of yet.

 

Linux Mint 15 x86

 

I have a laptop HP NC8430 plugged into a docking station (DVI -> HDMI Out), plugged into a Yamaha RX-V565, output via HDMI to a Samsung BX2450 LCD Monitor.

I am having an issue with the resolution detected / set at the MDM login screen which is automatically picking up the LDP resolution (16:10, 1680x1050) when I have my external LCD monitor (16:9, 1920x1080) On and the laptop lid closed. Unfortunately, the Yamaha only accepts VGA table resolutions or 16:9 resolutions so outputting 1680x1050 causes blank/flicking screen where I see the display for 0.5 seconds before showing snow or blank output. Display mirroring seems to be the culprit.
When I can eventually set the resolution (takes up to 15 mins a go) via click and guess, it works great.

Is there a way of setting the resolution of MDM / Login screen to 1280x768?
Or is there a way of setting the maximum resolution of the LDP to 1280x768?
Display mirroring is getting forced ON if I undock / re-dock either live or between reboots, can this be disabled permanently?

[Karl L.]

You can set the display properties for each monitor individually by creating a /etc/X11/xorg.conf and configuring it for multiple monitors as described in the Arch wiki.

[Aergan]

You can set the display properties for each monitor individually by creating a /etc/X11/xorg.conf and configuring it for multiple monitors as described in the Arch wiki.

 

Any alternatives without manually specifying a xorg.config?

[Karl L.]

Alternatives to xorg.conf for your login screen? Most likely not. Per-user configuration can be done fairly easily using the display settings utility built into your desktop environment or directly using xrandr, but that does not take affect until after you login. There is no solution I can think of that is simpler than editing xorg.conf. Your /etc/X11/xorg.conf should probably look like the following assuming your monitor is to the right of your laptop, your internal monitor is LVDS-0, and your external monitor is DVI-0:
 

Section "Monitor"
    Identifier  "LVDS-0"
    Option      "PreferredMode" "1680x1050"
    Option      "Position" "0 0"
EndSection

Section "Monitor"
    Identifier  "DVI-0"
    Option      "PreferredMode" "1920x1080"
    Option      "Position" "1680 0"
EndSection

The thing that is most likely to be wrong with this configuration is the monitor identifiers. I don't actually know how your monitors are identified, but as long as you can login you can discover the identifiers fairly easily using xrandr.

xrandr --current

[Aergan]

Thanks for the info, I'll do some reading.

 

I'm not after dual-head at all though thanks - forgive me if I didn't mention it.

 

I want the laptop to run just via external display LCD when the lid is closed and LDP only when open (I have had this working previously on Xubuntu 12.04 without needing to do anything a year ago).

[Karl L.]

Auto-detection in X is pretty good, in general. When it works, it works well - which is probably why it worked for you automatically in Xubuntu 12.04. Theoretically it sounds like it should work in Linux Mint, but it would be kinda difficult to pin the issue in Mint to one thing specifically. Your best bet would be to compare your /var/log/Xorg.0.log from both, but even then it might be a little difficult to pinpoint the difference causing that particular inconsistency.

[Aergan]

I'm starting to think it's to do with having a newer kernel / radeon open source driver as when I tried Ubuntu 13.04 last month, plugging in or booting to an external monitor 16:9 caused it to crash X -> hard lock whereas with Mint 15 (based on 13.04) I have had no such issue (other than the amp complaining about resolutions it does not support). Same issue persisted to both x86 and x64 variants of stock ubuntu as well but connecting an external 16:10 was fine.

 

What is weird is that I'm on the same kernel version now as I was with stock ubuntu (3.8.0.19-generic) and all is well.

aergan@ASTROTRAIN ~ $ xrandr --current
Screen 0: minimum 320 x 200, current 1920 x 1080, maximum 8192 x 8192
VGA-0 disconnected (normal left inverted right x axis y axis)
LVDS connected (normal left inverted right x axis y axis)
   1680x1050      59.9 +
   1400x1050      60.0  
   1280x1024      59.9  
   1440x900       59.9  
   1280x960       59.9  
   1280x854       59.9  
   1280x800       59.8  
   1280x720       59.9  
   1152x768       59.8  
   1024x768       59.9  
   800x600        59.9  
   848x480        59.7  
   720x480        59.7  
   640x480        59.4  
S-video disconnected (normal left inverted right x axis y axis)
DVI-0 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080      60.0*+   50.0  
   1920x1080i     25.0     30.0  
   1600x1200      60.0  
   1680x1050      59.9  
   2880x576       50.0  
   2880x480       59.9  
   1280x1024      75.0     60.0  
   1440x900       75.0     59.9  
   1280x960       60.0  
   1280x800       59.9  
   1152x864       75.0  
   1280x720       50.0     60.0  
   1440x576       50.0  
   1024x768       75.1     70.1     60.0  
   1440x480       59.9  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   720x576        50.0  
   720x480        59.9  
   640x480        72.8     75.0     66.7     60.0  
   720x400        70.1  
aergan@ASTROTRAIN ~ $