You have been subscribed to a public bug: Display corruption may result when using multiple monitors when one of the monitors is connected to the video card but does not have power.
Ubuntu version is 11.04, desktop 32-bit edition. I was running the live version off a 4 GB USB drive. The problem occurs regardless of whether using persistence or not. I am using an ATI Radeon X600 which has dual DVI-I connectors. One connector was attached to a Dell flat panel, E197FP, and the other to an LG L1750S. Both connections were analog, using a DVI-VGA adapter. The problem occurs under these circumstances: Both monitors are connected to the video card. The Dell monitor is on and being used as the main display. The LG monitor does not have a power connection. Note! This does not mean it was simply not turned on; I mean it actually did not have the power cable plugged in. In this scenario, severe display corruption may result. I repeated this test many times. I observed that after the splash screen, the desktop would display fine for one or two seconds and the mouse would be movable. However after those one or two seconds, the mouse would freeze, and the display would go blank for one or two seconds. When the display returned, the desktop wallpaper was gone and the display was behaving very strangely. I will attach some screen shots. This problem does NOT occur if: * only one monitor is connected to the video card, and it is receiving power * both monitors are plugged in and receiving power--regardless of whether they are actually turned on or not Having the monitor on or off is irrelevant; it is when the monitor is connected to the video card but does not have a power connection at all. This causes the software to be unable to read the monitor's configuration. Another interesting note is that I could switch back and forth to the text terminals (Ctrl+Alt+F#) and the graphic display. While the text terminals were always displayed correctly, the graphic display would be corrupted in different ways when I switched back to it each time. Sometimes it would look and act normal. Other times it would act like it does when it first boots (no wallpaper, things not erasing, background not redrawing). Other times it is completely corrupted, displaying only colored bars and patterns. Even in this state, though, I could sometimes switch to a text terminal and back and the graphical display would be semi-usable. Screenshot 1: Background does not redraw when dragging window until the mouse is released. IMPORTANT: The right half of the image appears in the screen shot but not on screen. The vertical program bar is NOT actually visible on the monitor. Screenshot 2: Example of menus not erasing. In this screenshot, I first pulled down some of the menus from the menu bar at the top of the screen. When the menu closes, the background is not redrawn, but the menu simply turns a light gray. Notice the remnants of the menu to the upper left corner of the window. You can see the "Location" menu item somewhat. IMPORTANT: Again, in this screen shot, only the left half is visible in reality. The right half of the image, including the vertical program bar, is not visible on screen. Screenshot 3: Colored bars/pattern corruption. IMPORTANT: In reality the pattern covered the ENTIRE screen and the right half of the screen was not visible. On the actual display, the left half of the image was completely covered in colored bars, and the right half of the image, including the vertical program bar, were not visible. At the end of the dmesg output there is a very good hint. Screenshot attachments and dmesg output coming momentarily. ** Affects: xserver-xorg-video-ati (Ubuntu) Importance: Undecided Status: New -- Display corruption, multi monitor, Radeon X600, Invalid EDID https://bugs.launchpad.net/bugs/786781 You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-ati 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