[Bug 26787] Radeon HD 4650 black screen at 2560x1600

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=26787

--- Comment #10 from Nicos Gollan <gtdev at spearhead.de> 2010-04-18 07:23:32 PDT ---
(In reply to comment #0)
> Using a Radeon HD 4650 with a LG W3000H screen, with either git drivers or the
> ones that come with the ubuntu lucid beta, results in a black screen on boot.

I'm getting something similar, and I have something for you to try:

Start the system with UMS (i.e., the radeon.modeset=0 kernel parameter). When
you are on the login screen, switch to a console, kill the desktop manager, and
unload the "radeon" module. Once you unloaded it successfully, try manually
loading it with the "modeset=1" parameter. If you get a high-res console then,
start the desktop manager, and you should be fine.

Fun thing is, that usually works for me, I get working KMS even on a
dual-monitor setup on a Radeon HD4350 and an HD4870 that way, on the 4350 it
will run stable for several weeks with an OpenGL accelerated KDE desktop
without even showing graphical glitches. However, if I start without the
modeset=0 parameter, my system will come up with a black screen once the module
is (auto)loaded, and eventually freeze.

I tried debugging via serial console, but nothing unusual came up.

Running a 2.6.33 kernel from Debian experimental repository, as well as radeon
X drivers from there (currently 6.13.0).

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