Samsung 712N and xorg.conf

[Craig White]

On Sun, 2007-12-09 at 11:13 -0700, Jerry Davis wrote:
> On Sunday 09 December 2007 10:35, Matt Graham wrote:
> > From: Jerry Davis <jdawgaz at cox.net>
> >
> > > On Sunday 09 December 2007 08:48, Matt Graham wrote:
> > > > From: Jerry Davis <jdawgaz at cox.net>
> > > >
> > >>> I am trying to get my Dad's computer working with his Samsung
> > >>> SyncMaster 712N, and am having some trouble.
> > >>> Samsung SyncMaster 712N
> > >>> HorizSync 31.5 - 48.5
> > >>> VertRefresh 40.0 -70.0
> > >>
> > >> Are those accurate?  LCDs may need higher ranges for these than the
> >
> > monitor
> >
> > >> can actually do, because LCDs don't *have* Hsync and Vsync
> > >
> > > don't really know. my Dad just emailed me, that he got it to work at
> > > 800x600
> > >
> > > and he can see the full screen now.
> > > how is the resolution in X11 tied to the sync and refresh rates? could
> > > bad values make the "native" resolution not be possible?
> >
> > "Native" should not be in quotes here.  Unlike CRTs, LCDs have one and only
> > one
> > optimal resolution; the resolution that exactly corresponds to the number
> > of pixels they have.  X is very conservative wrt sync rates, and if you
> > take a look at /var/log/Xorg.0.log, you might see a line like "Mode
> > 1280x1024 discarded due to inadequate Hsync".  I have an LG
> > something-or-other LCD that's
> > 1280x1024, and all normal Modes work fine.  (Doublescan modes = barf, but I
> > don't really need anything below 640x480.)  Hsync is 30-95, Vsync is
> > 55-160. Those numbers were copied directly from my old CRT.
> >
> > >>> Modes "1024x768" "800x600" "720x400" "648x480"
> > >>
> > >> Google says the Samsung 712N has a native resolution of 1280x1024.  So
> >
> > edit
> >
> > >> xorg.conf and add that Mode to the Modes line, then restart X.
> >
> > Did he do this, or not?
> >
> 
> yes he did, and he got a startup error on X
> so I told him to leave the Modes line completely out, and try to see what is 
> Autodetected, and up came 800x600 which he says he is content to be in.
----
that seems really odd.

Anyway, if things have gotten that out of control, the way to handle it
on CentOS/Red Hat systems would be...

Log out as User
Press <Control><Alt><F1> # to get text console
Login in a root
Type 'init 3'
Type 'system-config-display --reconfig'
Click on tab 'Hardware'
Click on button 'Configure' for Monitor
Click on triangle alongside 'Generic LCD'
Select '1280x1024'
Click 'OK'
Click on tab 'Settings'
Choose '1280x1024'
Click 'OK'
Things should be set now but easy enough to test...
Type 'startx' and press <Enter>

- If things look good, log out of GUI
  Type 'init 5'

- If things don't look good, repeat starting at 'system-config-display
--reconfig'

Craig