(In reply to comment #4)
> But if you can suggest a version to test I can start.

I haven't seen any other similar reports, so if it happens with 3.7 kernels,
it's probably not a (recent) kernel regression.

> I have seen other people running the Intel drivers reporting this same sort
> of error (the missing busID in the drmGetBusid call), and they thought it
> was a race condition

That seems unlikely in your case, given the timestamps in the log snippets
you've provided.