Imac Radeon HD 4850 switch "Mini Display Port" output during install resulting black screen
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Fix Released
|
Medium
|
Unassigned |
Bug Description
I tried to install Lucid on the new Apple Imac27" with ATI radeon HD 4850 video card. After selected "install", the screen goes black. few investigations later, I discovered display output switch to the Mini Display Port. So, I tried to connect a second screen, and I was right : just after select "install lucid", the video output switch to the second screen, and the main screen turn black.
I continue my installation using my 2nd screen (connected to the mini display port), and after it, I'm on the desktop. I activate Open radeon drivers, they works perfectly, but in the second screen (Vsync is perfect, and very smooth using compiz). Impossible to switch to the main screen. It's not recognized, and stay black.
I tried proprietary ati drivers (10.6). With them, I can activate my main screen, but they are not better than the open ones : there is a big vsync bug. Actually, It's totally impossible for a normal user to use open ati drivers on the main screen with an Imac27 and ati radeon 4850 graphic card.
I think issue is in the kms driver, I tried to deactivate them. Main screen is recognized, but impossible to turn it on, it stay black, and Vsync issue re-appear on the second screen. Maybe the open radeon drivers also got a bug, cause after deactivate them, my main screen is now recognized on display manager, but impossible after activate it, it stay black => back to proprietary drivers, and the Vsync issue)
i tried 2.6.32, 2.6.34, 2.6.35 rc1 released, bug is still here.
tags: | added: kj-triage |
tags: | added: acpi-apic |
Changed in linux (Ubuntu): | |
status: | New → Confirmed |
importance: | Undecided → Medium |
tags: | added: kernel-key |
tags: | removed: kernel-key kj-triage |
I've been suffering this problem on my new iMac 21.5 (11,2 i3, Radeon 4670). All linux live CDs would give black screen even though I could hear the disc loading up.
I've got round the problem for my system by doing two things:
1 connecting an external monitor through the Mini Display port.
2 Using F6 on the grub boot menu to add options - radeon.modeset=0 nomodeset
I don't know if the radeon modesetting works on the external monitor (LG1710, has worked OK on a Mac Mini but will test it on iMac) but it certainly doesn't work on the main monitor.
I've only tried live CDs so far; in 'xrandr' the main monitor is identified as eDP-0 and it lists the full range of supported resolutions up to 1920x1080.