On Thu, May 14, 2020 at 09:59:52AM +0200, Gerd Hoffmann wrote:

  Hi,

quoted

- for the runtime upcasting the usual approach is to check the ->ops
pointer. Which means that would need to be the same for all virtio
dma_bufs, which might get a bit awkward. But I'd really prefer we not
add allocator specific stuff like this to dma-buf.

This is exactly the problem, it gets messy quickly, also when it comes
to using the drm_prime.c helpers ...

drm_prime.c helpers (not the core bits) exist becaues nvidia needed
something that wasnt EXPORT_SYMBOL_GPL.

I wouldn't shed a big tear if they don't fit anymore, they're kinda not
great to begin with. Much midlayer, not much of valued added, but at least
the _GPL is gone.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch