Custom resolutions on i855GME with modesetting

Matthew Hodgson matthew at arasphere.net
Wed Feb 28 17:49:35 PST 2007


Hi,

I've just built a modular xorg from git head in order to play with the 
modesetting branch of the intel drivers on an i855GME based motherboard 
(http://www.ibase-i.com.tw/mb890.htm).  I want to use the motherboard as a 
TV playout box, and as such I'm trying to feed it a modeline for 
displaying widescreen progressive PAL (1024x576 at 50Hz) on a projector via 
DVI.  Nothing's plugged into the HD15, LVDS or composite/s-video outputs 
on the board.

My problem is twofold:

a) The modesetting driver appears to ignore the modeline i've specified in 
my xorg.conf, and instead generates only a 1024x768 at 60Hz picture.

b) On killing Xorg, the box hangs solid.

The xorg.conf and Xorg.0.log for this may be found at 
http://www.arasphere.net/xorg/modesetting-20070301

If anyone can confirm whether the modesetting driver should let me program 
a custom mode like this, and how I override the 1024x768 modeline, i'd be 
very grateful :)

For what it's worth, I've had the machine outputting 1024x576 at 75Hz by 
patching the VBIOS using 855resolution with Xorg 6.8 and default i810 
drivers, so I know it should be possible - I'm hoping that the modesetting 
driver will let me get a properly tv-standards-compliant 50Hz refresh rate 
which I can sync to for frame-accurate video playback using an XV or GLX 
wait-for-vsync API of some kind.

Finally, should the modesetting driver support interlaced display modes 
(and if so, is there any API for determining which field is currently 
being displayed)?

thanks in advance,

Matthew.



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