AMD A10 7700K + ATI Radeon HD 6850 with 6 Monitors

Question

I'm running a workstation with (hopefully) 6 monitors under LM17 Cinnamon, 64-bit.

The AMD ATI Radeon HD 6850 comes with 2x DVI, HDMI and DP to connect to 4 displays, which work fine under the xserver-xorg-video-ati drivers. The AMD APU A10 7700K includes a R7 series GPU to handle multiple monitors, in my case 2 displays, at the DVI / HMDI or VGA port.

Under Windows ATI Eyefinity all 6 monitors work in this environment.

I'm having trouble to get the APU GPU cores to work under Linux.

ATI Cataclyst drivers repeatedly crash Cinnamon; I've tried version 14.6. I needed to purge all graphic drivers >amdcccle and the xserver<, to get Cinnamon in Software Rendering Mode. So now I'm running 4 displays at the Graphicscard under the xserver-xorg-video-ati drivers.

$ inxi -Gxz
Graphics:  Card: Advanced Micro Devices [AMD/ATI] Barts PRO [Radeon HD 6850] bus-ID: 01:00.0 
       X.Org: 1.15.1 drivers: ati,radeon (unloaded: fbdev,vesa) Resolution: 1920x1080@60.0hz, 1920x1080@60.0hz, 1920x1080@60.0hz, 1920x1080@60.0hz 
       GLX Renderer: Gallium 0.4 on AMD BARTS GLX Version: 3.0 Mesa 10.1.3 Direct    Rendering: Yes

Can someone suggest some way to get the APU to work with the last 2 displays? No 3D / gaming and so on is required. Just plain 2D applications.

Thx in advance.

edit 1:
By now I have 6 displays running in mirrored mode with APU & gfxcard. I still didn't get them to run on a real multiscreen.

$ inxi -Gzx
Graphics:  Card-1: Advanced Micro Devices [AMD/ATI] Kaveri [Radeon R7 200 Series] bus-ID: 00:01.0 
       Card-2: Advanced Micro Devices [AMD/ATI] Barts PRO [Radeon HD 6850] bus-ID: 01:00.0 
       X.Org: 1.15.1 drivers: ati,radeon (unloaded: fbdev,vesa) Resolution: 1920x1080@60.0hz, 1920x1080@60.0hz, 1920x1080@60.0hz, 1920x1080@60.0hz, 1920x1080@60.0hz, 1920x1080@60.0hz 
       GLX Renderer: Gallium 0.4 on AMD KAVERI GLX Version: 3.0 Mesa 10.1.3 Direct Rendering: Yes

edit2:
I achieved two display groups with ATI drivers. Cinnamon DE repeatedly crashes. 3x1 matrix running one desktop, the other running 3x1 desktop but it only shows the mouse.... both APU & gfxcard are recognized.

$ inxi -Gzx
Graphics:  Card-1: Advanced Micro Devices [AMD/ATI] Kaveri [Radeon R7 200 Series] bus-ID: 00:01.0 
       Card-2: Advanced Micro Devices [AMD/ATI] Barts PRO [Radeon HD 6850] bus-ID: 01:00.0 
       X.Org: 1.15.1 driver: fglrx Resolution: 5760x1080, 5760x1080 
       GLX Renderer: AMD Radeon R7 Graphics, AMD Radeon HD 6800 Series GLX Version: 4.4.12967 - CPC 14.20 Direct Rendering: Yes

Edit3:
By now the problem (only) seems to be xinerama to connect both desktops. When I activate the option and reboot, all six monitors turn "black" (with only the mousecursor moving) after loginscreen... Is there an alternative? Or am I doing something wrong?

Answer 1

problem solved. get rid of cinnamon, install xfce.

$ inxi -Gxz
Graphics:  Card-1: Advanced Micro Devices [AMD/ATI] Kaveri [Radeon R7 200 Series] bus-ID:   00:01.0 
       Card-2: Advanced Micro Devices [AMD/ATI] Barts PRO [Radeon HD 6850] bus-ID: 01:00.0 
       X.Org: 1.15.1 driver: fglrx Resolution: 5760x2160 
       GLX Renderer: AMD Radeon HD 6800 Series GLX Version: 4.4.12967 - CPC 14.20 Direct    Rendering: Yes

cinnamon DE is incapable of supporting Xinerama and amdcccle dual desktop groups. cinnamon fails to load probably with two desktops group in fglrx drivers. and blackscreens on activision of Xinerama.