RE: Monitor detection failure and video display
----Original Message----
From: Camaleón [mailto:noelamac@gmail.com]
Sent: Friday, October 08, 2010 9:23 AM
To: debian-user@lists.debian.org
Subject: Re: Monitor detection failure and video display
> On Thu, 07 Oct 2010 11:58:51 -0800, James Zuelow wrote:
>
>> Some additional info.
>>
>> I tried this:
>>
>> Section "Device"
>> Identifier "Device0"
>> Driver "nouveau"
>> Option "IgnoreEDID" "true"
>> EndSection
>>
>> But I get this in /var/log/Xorg.0.log (actually I get that error if
>> the IgnoreEDID is there or not):
>
> Mmm, I don't think that should be the proper way to handle that
> (unless you know for sure that EDID information is completey broken
> with your monitor and you are then forced to disabled it).
No, you're right. I was way off, thinking it was xorg failing to get EDID info from a monitor that was causing the video to go blank.
I was just playing with this and it turns out it was pretty simple.
With the new 2.6.32 kernel in Squeeze, KMS is turned on. KMS attempts to autodetect a monitor, and if it doesn't find one video goes blank. The way around this is to override KMS with the video= boot parameter.
So I modified /etc/default/grub and changed the boot options from "quiet" to "quiet video=VGA-1:e"
The "video=VGA-1:e" tells the kernel to enable VGA-1 regardless of what it sees. Then xorg will start. It still won't get EDID info if the monitor is powered off, but I can set a specific mode for the monitor which seems to work.
I have an image I use for kiosks, so after applying the image to a computer I have to tweak the video= kernel option for each one, but that's not really an issue as I have to tweak the xorg.conf mode setting for each monitor anyway. It is just a matter of figuring out which video setting to use, VGA-1 for the VGA ports, or DVI-I-1 for a DVI port. I can't find the code for an S-Video output, which is really handy for display kiosks using a large screen TV as a display unit (especially cause you can push an s-video signal over a 50 or 100 foot cable).
If I wanted to, I could set the display setting in the kernel command line as in "video=VGA-1:1920x1080@52e" This would set the display to 1920x1080 at 52Hz refresh. I might need to do that with some of the bigscreen TV's, and probably have to do that for anything going over the S-video port if the xorg.conf modeline doesn't work for some reason.
Anyway, it is working now, and this should be enough info to get people going on a Google search if they're in the same boat.
James Z
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