I have a Sony Vaio VPCCB-27FX with hybrid graphics. Using vgaswitcheroo enables me to switch my discrete card off to save power. Now when i want to switch to the discrete card for performance, my system freezes.

I already tried logging out and killing x with service lightdm stop, but still, it freezes as soon as I echo DIS > switch. typing blindly, echo IGD > switch returns me to my console where it reads [ 179.555171] i915: switched off, but it seems the discrete card never gets switched on... running echo DDIS > switch gives me the following:

[540....] [drm:atop_op_jump] *ERROR* atombios stuck in loop for more than 5secs aborting
[540....] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing CEE2 (len 62, WS 0, PS 0) @ 0xCEFE
[540....] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing BBF6 (len 1036, WS 4, PS 0) @ 0xBCF3
[540....] [drm:atom_execute_table_locked] *ERROR* atombios stuck executing BB8C (len 76, WS 0, PS 0) @ 0xBB94
[541....] [drm:r600_RING_TEST] *ERROR* radeon: ring test failed (scratch(0x8504)=0xFFFFFFFF)
[541....] [drm:evergreen_resume] *ERROR* evergreen startup failed on resume

after that, the atombios part repeats a few times.

also, the terminal locks up again and sysrq+REISUB is my only rescue.

Has anybody an idea how I can switch to my discrete card without the system locking up?

#uname -srvmpio
Linux 3.2.0-24-generic #39-Ubuntu SMP Mon May 21 16:52:17 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
#lsb_release -r
Description: Ubuntu 12.04 LTS