Created attachment 107497 [details] [review]
Possible fix

(In reply to Marek Olšák from comment #21)
> The context should be fully initialized to do anything no matter what the
> user API is, is that right, Christian?

Correct, yes. The context is the same we do CC conversion with and there it
works perfectly fine. We also hold a lock to make sure that the context isn't
used by more than one theread at the same time.

> The auxiliary context is for cases when you don't have any context around
> and need to submit some commands. It saves the context_create/destroy
> overhead but not much else. If the context created by VDPAU isn't
> initialized properly, the aux context can be used (if it works).

Well, using the auxiliary context migth work around the problem but won't
really solve it. Anyway a patch going this approach is attached, please test.