I'm sorry for the delayed response. I was away for a week and then put on another project.
I haven't had a chance to test this theory yet:
I was working with a board supplied by RTD which has both VGA and LVDS output, I have been having problems with Win XP & 7, and ubuntu 12.04 forcing the system to use the LVDS output instead of the VGA. The ARM board I've been working with has an LVDS output too, so I'm wondering whether when Linux has finished booting, it switches the display to LVDS out. I'm not sure how to check which output the kernel uses yet, but I'll post an update when I've verified this?
Perhaps it is a setting in the BIOS, if the system has one?
Originally Posted by AJEllisuk
I put my theory to the test, whilst I don't have a suitable LVDS display, I was able to observe activity on the pins of the connector with an oscilloscope at the same time as when there was an output to the VGA display, and the activity stopped when the VGA was stopped.
This system doesn't have a bios, the chip I'm using (MCS8144) has an iROM (I think Internal ROM) which allows the system to be flashed using tftp and serial terminal. Under normal operation the system loads a bootloader (uBoot) whuich then loads linux. For some reason when linux finishes booting, the frame buffer is disabled.