Public bug reported:
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.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
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Imac Radeon HD 4850 switch "Mini Display Port" output during install resulting
black screen
https://bugs.launchpad.net/bugs/597070
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