Comment 13 for bug 981168

The lspci -v command should return a large amount of text. Search for your graphic card in it (usually starts as "VGA compatible controller") and see the "Kernel driver in use" line in the graphic card block.

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
 Subsystem: Dell Device 050e
 Flags: bus master, fast devsel, latency 0, IRQ 51
 Memory at f1400000 (64-bit, non-prefetchable) [size=4M]
 Memory at e0000000 (64-bit, prefetchable) [size=256M]
 I/O ports at 4000 [size=64]
 Expansion ROM at <unassigned> [disabled]
 Capabilities: <access denied>
 Kernel driver in use: i915
 Kernel modules: i915

As you can see, in my case it's i915, and i945 seems to be the affected driver.