Subject: Re: problems with X configuration
To: None <>
From: Wolfgang Solfrank <>
List: current-users
Date: 01/05/2005 15:46:07

> This is what I love about X...  I've received several different, 
> mutually contradictory, answers.  One gave explicit numbers except for 
> one value, which was suggested were likely in the 60-80 range.  This 
> answer says it's more likely to be around 160.  (Aside: this line 
> appeared in the log -- does that support the 160 hypothesis?)
> (II) VESA(0): clock: 162.0 MHz   Image Size:  367 x 275 mm

Yes, I think so.

Anyway, if all else fails, RTFM:

man XF86Config
        ModeLine  "name" mode-description
               This entry is a more compact version of the Mode entry,  and  it
               also  can  be used to specify video modes for the monitor.  is a
               single line format for specifying video modes.   In  most  cases
               this  isn't  necessary because the built-in set of VESA standard
               modes will be sufficient.

               The mode-description is in four sections,  the  first  three  of
               which  are mandatory.  The first is the dot (pixel) clock.  This
               is a single number specifying the pixel clock rate for the  mode
               in MHz.  The second section is a list of four numbers specifying
               the horizontal timings.  These numbers  are  the  hdisp,  hsync-
               start, hsyncend, and htotal values.  The third section is a list
               of four numbers specifying the vertical timings.  These  numbers
               are  the  vdisp,  vsyncstart,  vsyncend, and vtotal values.  The
               final section is a list of flags specifying  other  characteris-
               tics  of  the mode.  Interlace indicates that the mode is inter-
               laced.  DoubleScan indicates a mode where each scanline is  dou-
               bled.   +HSync  and -HSync can be used to select the polarity of
               the HSync signal.  +VSync and -VSync can be used to  select  the
               polarity  of the VSync signal.  Composite can be used to specify
               composite sync on hardware where this is  supported.   Addition-
               ally,  on some hardware, +CSync and -CSync may be used to select
               the composite sync polarity.  The HSkew and VScan  options  men-
               tioned  above  in  the  Modes entry description can also be used

The pixel clock is exactly that, i.e. the speed of pixel information sent from
the video card to the monitor.  The horizontal and vertical timing parameters
specify the blanking intervals that are neccessary to synchronize the picture
information to the screen.  Note that while those wouldn't be strictly
neccessary for flat panels, you have to allow for those nevertheless.

Anyway, just as one other mail said, VESA/DDC should have found this out
automagically for you, so I don't think that it will help much.

ws@TooLs.DE				Wolfgang Solfrank, TooLs GmbH