How are you adding the interlaced mode? Is it part of the edid from your monitor or a modeline or added at runtime using xrandr? As has been noted, I suspect the xserver may be mangling interlaced modes. Can you attach your xorg log?
How are you adding the interlaced mode? Is it part of the edid from your monitor or a modeline or added at runtime using xrandr? As has been noted, I suspect the xserver may be mangling interlaced modes. Can you attach your xorg log?