Bug#627554: xserver-xorg-video-radeon: HD 5750 3rd screen displays interesting psychedelic colour swirl pattern covering whole screen

[Alex Deucher]

On Sat, May 21, 2011 at 6:11 PM, Tim Wootton <tim at tee-jay.demon.co.uk> wrote:
> Package: xserver-xorg-video-radeon
> Version: 1:6.14.1-1+b1
> Severity: normal
> Tags: upstream
>
> When trying to get 3 screens working off an HD 5750, one of the screens is coming up with cyan-ish background part way through boot, and when x launches I get an interesting psychedelic colour swirl across that whole screen. It's just possible to make out shapes of icons, windows etc. that should be displayed on the screen.
>
> In troubleshooting I have discovered that if I install the closed source driver & reboot, and then uninstall it and reboot again back into the open driver then the 3 monitor setup works fine with the open driver. I think the closed driver must be setting somthing up during boot that allows the open driver to work with the 3rd screen so long as I havn't removed power completely & only booted with a reset.
>
> I can tell early in the boot which screen is going to have the problem by the cyan background.
>
> I have the monitors connected to the 2xDVI and 1xHDMI, the DP is unused.

Not a bug.  Only 2 non-DP monitors are supported since there are only
two plls.  If you want 3 or more monitors the rest have to be DP.  The
fact that you can make it work with some fiddling is pure luck and is
completely unsupported.  You end up with one of the plls driving two
monitors which only works if both monitors have the same clock and you
get the ordering right.

Alex