I'm forwarding a Ubuntu bug reporter's report:
xdpyinfo is reporting incorrect physical screen dimensions for a LGPhilipsLCD LP154W01-TLD (eisa: LPLbc00, edid: "LPL" prod id 48128). xrandr correctly reports the dimensions as 331mm x 207mm, and ddcprobe reports screensize: 33 21, yet xdpyinfo reports (300x230 millimeters). Xorg.0.log does not report what it took from edid in this case, but does indicate it used a 96x96 dpi.
This error causes DPI's to be set incorrectly in some applications (like Firefox). xdpyinfo is reporting the dpi to be 108x88, which may be what FF and other apps are using.
I notice that a similar monitor from this manufacturer, LGPhilipsLCD LP154W01-A5, was quirked in quirk_detailed_use_maximum_size() (bug #10304). Perhaps it simply needs a quirk for this monitor as well?
[Also see bug #15682 which has a similar problem with a different monitor and may also need this same quirk.]
I am observing DPI set to 96. Is this the same or different bug? As the user in
I use the "intel" driver and I have an LG monitor (L1919S) attached by VGA.
In Xorg.0.log I see that the Intel reports the correct dimensions in cm for my monitor. I also have an LVDS connected monitor which is disabled in xorg.conf.
Xorg reports wrong screen size by design. See bug 23705
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