[Intel-gfx] [RESUBMIT PATCH v2] tests/prime_vgem: Skip basic-read/write subtests if no mappable GGTT

[Chris Wilson]

Just s/no mappable GGTT/not supported/

Quoting Janusz Krzysztofik (2019-11-26 12:31:03)
> As we've agreed that using I915_GEM_PREAD/PWRITE IOCTLs on dma-buf
> objects doesn't make much sense, we are not going to extend their
> handlers in the i915 driver with new processing paths required for them
> to work correctly with dma-buf objects on future hardware with no
> mappable aperture.  When running on that kind of hardware, just skip
> subtests which use those IOCTLs.
> 
> v2: Examine pread/pwrite ABI, not mmap ABI (Chris)
> 
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>

I like this. We are not here to prove gem_read/gem_write
themselves work (if we haven't done that already, we've lost), but
whether they work in conjunction with the dmabuf.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

I still have a bad feeling about any API change not accompanied by a
separate parameter to indicate the change (just from the discoverability
aspect of the API), but as proven, an introspection API is not required
here.
-Chris