Although I'm not an Ubuntu user (I'm on Debian sid), I've a similar problem with the RadeonHD driver:
* Configuration - On-Board Radeon chip; lspci info: 01:05.0 VGA compatible controller: ATI Technologies Inc Radeon HD 3200 Graphics - radeonhd driver 1.2.5 - xorg-server 1.6.1.901 (from experimental) * Symptoms - ddcprobe shows correct dimensions: "screensize: 51 29" - Xorg seems to know proper size (from Xorg.0.log): (II) RADEONHD(0): Max Image Size [cm]: horiz.: 51 vert.: 29 - But later somehow comes up with incorrect numbers, which propagate into xpdyinfo: (II) RADEONHD(0): clock: 138.5 MHz Image Size: 477 x 268 mm - xdpyinfo: dimensions: 1920x1080 pixels (477x268 millimeters) - xrandr has the wrong numbers as well (this is different from the original reporter, who had xrandr being right): DVI-D_1 connected 1920x1080+0+0 (0x3d) normal (normal left inverted right x axis y axis) 477mm x 268mm I'm sitting just in front of that monitor, and can help debugging this issue (assuming it's the same issue as the original reporter's). It seems to me that X is using two different ways to get physical screen size, and then chooses the wrong one. ** Attachment added: "Xorg log file" http://launchpadlibrarian.net/26822069/Xorg.2.log -- Screen DPI detected incorrectly by xdpyinfo https://bugs.launchpad.net/bugs/201491 You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in ubuntu. _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp