Safe Mode doesn't help. I have the same problem with a Mid 2012 MBPr with a fresh OS X 10.10 installation (no upgrade). In energy options I have enabled automatic graphic card switching, so my system is using the Intel HD Graphics 4000 mainly. The logs show a "GPU Reset" event:
-------------------
Mon Oct 20 20:36:37 2014
Event: GPU Reset
Data/Time: Mon Oct 20 20:36:37 2014
Application:
Path:
OS Version: Mac OS X Version 10.10 (Build 14A389)
Graphics Hardware: Intel HD Graphics 4000
Signature: 801
Report Data:
===========================================================================
Intel GPU Hang Summary
version 1.0.0
===========================================================================
-- Summary of Status for ALL Rings --
MAIN Ring is idle
MEDIA Ring is NOT enabled
BLT Ring is NOT enabled
===========================================================================
Essential Ring Registers
===========================================================================
-- MAIN Ring --
RING_HEAD = 0x00000048 (offset = 0x00000048, wrap count = 0, wait_for_cond = 0x0)
RING_TAIL = 0x00000048 (offset = 0x00000048)
RING_START = 0x10204000 (offset = 0x10204000)
RING_CTRL = 0x0000f001 (enabled, auto report disabled (0x00), not waiting, semaphore not waiting, length = 0x010 4KB pages)
-- MEDIA Ring --
RING_HEAD = 0x00000000 (offset = 0x00000000, wrap count = 0, wait_for_cond = 0x0)
RING_TAIL = 0x00000000 (offset = 0x00000000)
RING_START = 0x00000000 (offset = 0x00000000)
RING_CTRL = 0x00000000 (disabled, auto report disabled (0x00), not waiting, semaphore not waiting, length = 0x001 4KB pages)
-- BLT Ring --
RING_HEAD = 0x00000000 (offset = 0x00000000, wrap count = 0, wait_for_cond = 0x0)
RING_TAIL = 0x00000000 (offset = 0x00000000)
RING_START = 0x00000000 (offset = 0x00000000)
RING_CTRL = 0x00000000 (disabled, auto report disabled (0x00), not waiting, semaphore not waiting, length = 0x001 4KB pages)
- Common Slice INST_DONE register -
All Common Slice engines are done.
- INSTDONE_CS (=0xffffffff): Not done =
[....]
-----------------------
I already tried a PRAM- and SMC Reset, booted up in Safe Mode, repaired permissions. Since I disabled the automatic switching of graphic cards in system settings (so that it uses my NVidia Card as default), there are no freezes anymore. There seems at least one more user with the same problem:
Yosemite graphics problem?