[CentOS] [SOLVED] Problem with widescreen display

William L. Maltby CentOS4Bill at triad.rr.com
Mon Nov 10 10:00:28 UTC 2008


On Mon, 2008-11-10 at 00:20 +0000, Marko Vojinovic wrote:
> 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. ;-)

Well, I think its utility is such that it ought to be in the wiki hints.
If you have time and interest, why don't you ask the folks for access
and location in the wiki? Adding a little commentary about the meaning
of the values would make it useful to similar, but slightly different,
setups as well.

Glad you "fingered" it out.

> 
> Best, :-)
> Marko
> <snip>

-- 
Bill




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