[CentOS] [SOLVED] Problem with widescreen display

[Marko Vojinovic]

On Saturday 01 November 2008 22:08, Marko Vojinovic wrote:
> Basically, what I did was to run system-config-display to reconfigure for
> the new monitor and resolution. All goes well, but after X restarts, I see
> a strange picture: the resolution indeed goes to 1680x1050 as is supposed
> to, but is squeezed/shrinked/scaled horizontally to match a 4:3 aspect
> ratio, leaving two (unequal) black bands on the left and right side of the
> monitor.
[snip]
> The very same hardware and virtually same X configuration work perfectly ok
> on FC4
[snip]

Ok, just for the record, I resolved the issue, in the following way:

- took the exact modeline parameters for 1680x1050 (known to work) from FC4's 
Xorg.0.log and copy-pasted it into CentOS's xorg.conf
- also took the DisplaySize, HorizSync and VertRefresh parameters from the 
Fedora's log and put it into xorg.conf
- Disabled the DDC (undocumented option!!!)   <----- CRUCIAL  PART !!!
- took the modeline parameters for various other resolutions since without DDC 
nothing gets autoconfigured
- restarted X

Now everything works perfectly, and my hacked xorg.conf is just the default 
one with the following "Monitor" section:

Section "Monitor"
	Identifier	"Monitor0"
	ModelName	"LCD Panel 1680x1050"
# hacked DisplaySize --- note that the values are *wrong*,
# monitor is actually 470x300 mm
	DisplaySize	370	280
	HorizSync	31.5 - 90.0
	VertRefresh	60.0 - 60.0
	Option		"dpms"
# turned off the DDC; didn't know which option would do
# the job so put them both there
	Option		"NoDDC" "true"
	Option		"DDC" "false"
# various modelines, taken from Fedora's log:
	Modeline "1680x1050"  147.14  1680 1784 1968 2256  1050 1051 1054 1087 -hsync 
+vsync
	Modeline "1400x1050"  122.00  1400 1488 1640 1880  1050 1052 1064 1082 +hsync 
+vsync
	Modeline "800x600"   40.00  800 840 968 1056  600 601 605 628 +hsync +vsync
	Modeline "640x480"   25.20  640 656 752 800  480 490 492 525 -hsync -vsync
EndSection

Hopefully someone with a similar problem maybe finds this useful. ;-)

Best, :-)
Marko