Ever since Linux 3.11-rc4 (still present in 3.12-rc6), when both Radeon and
Intel GPUs are enabled on a hybrid graphics laptop, system freezes (well, the
picture freezes) every minute or two, then unfreezes and so on, making system
unusable.

When I disable radeon graphics card via vgaswitcheroo, freezes stop.

I have, however, discovered that when radeon driver gets loaded before i915
one, freezes happen. If i915 manages to get loaded before radeon, freezes don't
happen. When both are built into kernel, radeon driver gets always loaded
before i915.

This behaviour wasn't present in 3.11-rc3 kernel. Discrete card is Radeon HD
6450M and integrated one is Intel HD 3000.