[Gllug] Persuading X.org to give me the exact settings I asked for

[John Winters]

I'm having a slight problem with X.org apparently ignoring some of the
contents of its configuration file when starting up X.

I'm running a fresh Ubuntu 5.10 installation, with a Dell W1900 LCD TV.
The default resolution of the screen is 1280x768, with a preferred
refresh of 60Hz.  If you're a bit away from that it adjusts (at the
expense of clarity of image) but if you're too far away it sulks and
just puts up a message saying, "Change your resolution to 1280x768 at
60Hz."

I ran "dpkg-reconfigure xserver-xorg" which correctly detected my
monitor and offered me 1280x768 as the preferred resolution.  It's put
that in the configuration file too, but X chooses not to use it.  It
also seems to override the settings for the monitor's frequency limits,
which doesn't seem ideal.

The X configuration file (auto-generated) contains:

Section "Device"
        Identifier      "Intel Corporation 82865G Integrated Graphics
Device"
        Driver          "i810"
        BusID           "PCI:0:2:0"
EndSection

Section "Monitor"
        Identifier      "W1900 LCD TV"
        Option          "DPMS"
        HorizSync       28-49
        VertRefresh     43-72
EndSection

Section "Screen"
        Identifier      "Default Screen"
        Device          "Intel Corporation 82865G Integrated Graphics
Device"
        Monitor         "W1900 LCD TV"
        DefaultDepth    24
        SubSection "Display"
                Depth           1
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           4
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           8
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           15
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           16
                Modes           "1280x768"
        EndSubSection
        SubSection "Display"
                Depth           24
                Modes           "1280x768"
        EndSubSection
EndSection

but the corresponding log file produced at startup contains:

(II) I810(0): W1900 LCD TV: Using hsync range of 30.00-64.00 kHz
(II) I810(0): W1900 LCD TV: Using vrefresh range of 56.00-75.00 Hz
(II) I810(0): Not using mode "1280x768" (no mode of this name)
(1280x768,W1900 LCD TV) mode clock 100000MHz exceeds DDC maximum 110MHz
(II) I810(0): Increasing the scanline pitch to allow tiling mode (1280
-> 2048).(--) I810(0): Virtual size is 1280x1024 (pitch 2048)
(**) I810(0):  Built-in mode "1280x1024"
(**) I810(0):  Built-in mode "1024x768"
(**) I810(0):  Built-in mode "800x600"
(**) I810(0):  Built-in mode "640x480"
(II) I810(0): Attempting to use 60.02Hz refresh for mode
"1280x1024" (858)
(II) I810(0): Attempting to use 75.08Hz refresh for mode
"1024x768" (854)
(II) I810(0): Attempting to use 75.00Hz refresh for mode "800x600" (852)
(II) I810(0): Attempting to use 75.00Hz refresh for mode "640x480" (850)

so it appears to have ignored the frequency limits in the configuration
file and chosen its own, then it says it doesn't know what "1280x768" is
and substitutes instead modes of its own choosing.  Note that apart from
the first one chosen, they all have a refresh rate outside the limits
specified for the monitor.

How can I persuade X that I really do want 1280x768 at the specified
frequency?

TIA,
John

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