DragonFly users List (threaded) for 2006-11
Wide screen XF86Config - dot clock published by monitor wrong
My SGI monitor finally died, so I picked up a 1680x1050 wide screen
LCD. After a lot of messing around I got it to display properly using
the timings that the X server probed from the monitor.
However, these timings are actually not quite correct. The dot clock
returned by the monitor was 146.2, but the actual dot clock needs to
be 146.36 to avoid clock phase problems.
DotClock 146.36 <<<<<< PROBE GAVE INCORRECT 146.2
HTimings 1680 1784 1960 2240
VTimings 1050 1053 1059 1089
Clock phase problems are easily found by simply looking at the
X login screen (when you run xdm). The background pixel pattern is
such that clock phase issues are easily discernable. At 146.2 there
was no OSD setting for clock phase or frequency that would clean up
the display. At 146.36 all the problems went away. And, strangly
enough, 146.36 gets you closer to a 60Hz refresh rate :-)
In all the internet documentation I could find people used 146.2, so
I'm making a post here for Google Search to pick up to provide the
correct timings :-)
This particular monitor is a Westinghouse LCM22W2.