libdrm amdgpu semaphores questions

[Dave Airlie]

Hey all,

So I've started adding semaphore support to radv but I'm not really
sure what the API to the semaphore code is.

the Vulkan API is you get a command submission of a number of submit
units which have a 0-n wait semaphore, 0-n command buffers and 0-n
signal semaphores.

Now I'm not sure how I should use the APIs with those.

My first attempt is

call amdgpu_cs_wait_semaphore on all the wait ones, call the cs submit
API, then call the amdgpu_cs_signal_semaphore on all the signal ones?

or should I be up front calling wait/signal then submitting the command streams?

Also upcoming work requires possibly sharing semaphores between
processes, is there any indication how this might be made work with
the libdrm_amdgpu semaphore implementation?

Thanks,
Dave.