dual screen dpi bug in radon or Xorg?

Bernd Schubert bernd.schubert at fastmail.fm
Tue Nov 30 17:08:03 PST 2010

Bernd Schubert wrote:

> Hi all,
> xdpyinfo reports:
> screen #0:
>   dimensions:    3520x1200 pixels (410x310 millimeters)
>   resolution:    218x98 dots per inch
>   depths (7):    24, 1, 4, 8, 15, 16, 32
> Well, I have two screens... So the dimension in pixels is right, but in
> millimeters it is only the dimension of one screen...

Bug in the radeon driver, when one overwrites the screen size as I have to 
do for one my Dell screens, it takes the size of that overwrite for the 
overall size, instead of summing over all screen...

Section "Monitor"
        Identifier      "DELL_20"
        # Max Image Size [cm]: horiz.: 41  vert.: 31
        # but wrong clock: 162.0 MHz   Image Size:  367 x 275 mm
        DisplaySize     410 310
        Option          "PreferredMode"  "1600x1200"

Section "Monitor"
        Identifier      "DELL_24"
        Option          "PreferredMode"  "1920x1200"
        Option          "LeftOf"  "DVI-0"

And that results in Xorg logs in 

[    33.246] (II) RADEON(0): Setting screen physical size to 410 x 310

So instead of correcting the size for one screen, it corrects the overall 
screen size... Same with manually setting it with xrandr. At least I have a 
workaround now.


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