[PATCH libdrm] libdrm_amdgpu: add kernel semaphore support

[Dave Airlie]

>
> I can take a look at it, I just won't have time until next week most likely.

I've taken a look, and it's seemingly more complicated than I'm
expecting I'd want to land in Mesa before 17.2 ships, I'd really
prefer to just push the new libdrm_amdgpu api from this patch. If I
have to port all the current radv code to the new API, I'll most
definitely get something wrong.

Adding the new API so far looks like
https://cgit.freedesktop.org/~airlied/drm/log/?h=drm-amdgpu-cs-submit-raw

https://cgit.freedesktop.org/~airlied/drm/commit/?h=drm-amdgpu-cs-submit-raw&id=e7f85d0ca617fa41e72624780c9035df132e23c4
being the API, and whether it should take a uint32_t context id or
context handle left as an open question in the last patch in the
series.

However to hook this into radv or radeonsi will take a bit of
rewriting of a lot of code that is probably a bit more fragile than
I'd like for this sort of surgery at this point.

I'd actually suspect if we do want to proceed with this type of
interface, we might be better doing it all in common mesa code, and
maybe bypassing libdrm_amdgpu altogether, which I suppose the API I've
written here is mostly already doing.

Dave.