On 2010-08-26 17:37-0000 Nasa wrote:
----- "Alan W. Irwin" <ir...@beluga.phys.uvic.ca> wrote:
On 2010-08-26 10:47-0000 Nasa wrote:
Hi,
I am trying to configure a rather obscure resolution (800x480) which
is the
native resolution for my monitor. The monitor doesn't provide EDID
or DDC
information (it's connected over VGA). And the default settings by
the
driver produces displays that don't fit the monitor properly. I
would like
to construct a xorg.conf file with appropraite vertical refresh
rates, horizontal
syncs, and/or modelines to work correctly with the monitor.
However, there
doesn't seem a way to turn off the driver defaults for those items.
I tried options
like NoDDC, UseEDID, etc with no luck. I also tried using xrandr to
change
resolutions after X has started. The results end up being worse
than the
intial problem I was trying to fix (ie: the screen is bigger than
the area
available to display it). I expect my inability to find a suitable
solution
is due to my lack of knowledge -- so I hope someone can fill me in
to what
I am missing. Thanks in advance,
Earlier this year before I replaced my long-time Sony monitor with an
LCD, and upgraded from Debian Lenny to Debian testing, the results of
gtf and PreferredMode worked for me. For example, my xorg.conf file
for that monitor had the following lines in the Monitor section
#gtf 1024 768 85
# 1024x768 @ 85.00 Hz (GTF) hsync: 68.60 kHz; pclk: 94.39 MHz
Modeline "1024x768_85.00" 94.39 1024 1088 1200 1376 768 769 772
807
-HSync +Vsync
Option "PreferredMode" "1024x768_85.00"
Of course, intead of using the above example, you will want to run
something like
gtf 800 400 85
from the command line (man gtf), paste the results to your Monitor
section, and consistently update the identification of the mode used
by PreferredMode.
I emphasize the above configuration lines worked for an old version of
the
Intel driver (Debian Lenny), and I don't know whether they would
work
for a modern version. But it is worth a try.
Alan
Thanks Alan,
I actually attempted this via CVT which ended up with horizontal sync out
of range errors. Reading the MAN page for CVT didn't show any options to
put in options to set that. Does GTF have this capability?
No, but it doesn't matter. Play with either cvt of gtf (I don't think
there is any real difference between them) with a fixed resolution and
varying vertical refresh rate, and you will see that the horizontal
sync frequency of the generated mode line is proportional to the
vertical refresh you specify. So for your desired resolution if the
generated horizontal sync is lower than your allowed range, increase
the vertical refresh until you have a value within the allowed range.
Or if it is above (extremely unlikely for such a low resolution)
reduce the vertical refresh.
I have assumed above that the horizontal frequency limits have been
set correctly for your particular monitor. That is not always the
case. Check your monitor manual for the correct vertical and
horizontal frequency limits and if your X log shows those are not
being discovered properly by X than specify the correct ranges using the
VertRefresh and HorizSync values in the Monitor section. In my case
I used
HorizSync 30-96
VertRefresh 48-120
corresponding to values published in my Sony g200 manual, but your
monitor manual is very likely to require different ranges.
Alan
__________________________
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
__________________________
Linux-powered Science
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