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0e1f616
(Get the code!)
The problem could be reproduced with any kernel (tested 3.0.0 so far). Due to lack of AMD C1E idle accounting in kernel latency requirements cannot be enforced if needed (via pm_qos for instance) and apparently there are drivers that don't function correctly with the latencies added by AMD C1E, bttv is an example. There are also some wireless and sound drivers that might need c1e be disabled for their proper operation.
Of course a straightforward solution is to disable C1E in the BIOS or use idle=mwait kernel parameter. But why should the CPU use more power (and reduce battery life in case of a laptop) when C1E could just be disabled for the short moments if really needed.
The patch works for me, but someone with more knowledge about ACPI could point out where to read from the real latency value of C1E (for the time being it's on/off solution).