[SOLVED] Wrong EDID confuses dual monitor setup

[Nitro_146]

Hi all,

I Just upgraded my PC to Sandy bridge (core i5 2500K on Asrock z68 pro3-M) this week-end.
I just installed my old hard drive into the new box, tweaked some things, and everything is running fine ... except the dual monitor setup.

On my previous machine I had a nvidia card, and managed to make it work as expected (using a custom xorg.conf).
On the new machine I am using the integrated graphic controler with two TFT monitors :
- 1280x1024 on the VGA1
- 1920x1200 on the DVI1
The VGA is rotated, and placed on the left of the primary DVI.

The VGA only TFT panel is detected as only 1024x768 capable, and therfore the gui tool does not allow me to configure my setup as needed.

If I force the mode using xrandr, it works as expected.

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xrandr --addmode VGA1 1280x1024

However, altough I have searched the web, and tried some solutions, such as seting the xrandr in .xprofile or xdm init file, I am not satisfied. When X starts up, only one monitor is on. I have to manually deactivate it and reactivate again with the GUI tool to get my dual sceen working.
I did not succeed in writing a working xorg.conf file.
The login screen, that used to nicely display on the primary screen is now on both panels, and looks ugly (bad resolution).

[Jaglover]

I'm sure this can be solved with correct xorg.conf, there is also an option to ignore EDID and use custom settings.

[Nitro_146]

I know that it exists, but I have been unable to make a working xorg.com !

I find a lot of help using an nvidia or ati card, ant almost nothing for sandybridge igp.

Il will continue to search, since it took me 10 minutes this morning to get a working dual screen :'(

[Jaglover]

Xorg log usually gives good hints for xorg.conf.

[krinn]

emerge -a read-edid

you'll get your monitor settings (with luck last time i try it wasn't working)

[Nitro_146]

The problem with Xorg.log is that there is not errors... It just does not work as expected.

Concerning read-edid I already gave a try. The program just hangs when launched, doing nothing...

[anath0r]

I'm touched with similar problem after kernel upgrade on the same machine config (laptop + LCD).
Im trying to set resolution to 1650x1050. By default it always worked as xorg setting and now the logfile comes with sth like this:

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(II) intel(0): Output VGA1 using monitor section VGA1
(**) intel(0): Option "PreferredMode" "1680x1050"
(**) intel(0): Option "Primary" "True"
(II) intel(0): EDID for output VGA1
(II) intel(0): Printing probed modes for output VGA1
(II) intel(0): Modeline "1024x768"x60.0   65.00  1024 1048 1184 1344  768 771 777 806 -hsync -vsync (48.4 kHz)
(II) intel(0): Modeline "800x600"x60.3   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync (37.9 kHz)
(II) intel(0): Modeline "800x600"x56.2   36.00  800 824 896 1024  600 601 603 625 +hsync +vsync (35.2 kHz)
(II) intel(0): Modeline "848x480"x60.0   33.75  848 864 976 1088  480 486 494 517 +hsync +vsync (31.0 kHz)
(II) intel(0): Modeline "640x480"x59.9   25.18  640 656 752 800  480 489 492 525 -hsync -vsync (31.5 kHz)

As above I tried to make it work by xrandr but it doesn't solve the edid problem.

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anath0r@mistral ~ $ cvt 1680 1050
# 1680x1050 59.95 Hz (CVT 1.76MA) hsync: 65.29 kHz; pclk: 146.25 MHz
Modeline "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
anath0r@mistral ~ $ xrandr --newmode "1680x1050_60.00"  146.25  1680 1784 1960 2240  1050 1053 1059 1089 -hsync +vsync
anath0r@mistral ~ $ xrandr --addmode VGA1 1680x1050_60
anath0r@mistral ~ $ xrandr --output VGA1 --mode 1680x1050_60

BTW. Where is the best location to put these commands on autostart?

[Nitro_146]

My xrandr stuff is in /etc/X11/xdm/Init (I write this by memory, since I am not at home for one week)

If this can help, try to boot a ubuntu 11.10 live CD. On my system the ubuntu edid version works well and recognises the right settings for my monitor.

Il will check the versions used and try to update from ~amd64 to see if this work

[Nitro_146]

Curiously It is now working...

The only thing I changed, except some upgrade that are not related to Xorg nor intel driver are :

- Modify the kernel to support EFI GPT disks partitions
- Unplug/plug the monitor cable (I needed it for some testing on another computer).

Would it be possible that it was due to the VGA cable not being properly plugged ?

[s_bernstein]

Would it be possible that it was due to the VGA cable not being properly plugged ?

I don't think so. It's more likely that the crappy intel graphics driver had a good day and recognize your monitor or the updates you made did something to help with the problem.