[Intel-gfx] [PATCH 2/2] drm/i915/selftests: Compare mappable vma against instance in unmappable region

[Chris Wilson]

Quoting Abdiel Janulgue (2018-04-09 12:28:04)
> Add an additional comparison to check the entire vma created in the mappable
> region of the global GTT against the one in the unmappable range.
> 
> Further test with an assert_partial as well to ensure the VMA corresponds
> to the original object's backing store.
> 
> Signed-off-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>

It seems like instead of comparing two vma, you just need to compare the
vma->pages against the parent obj->pages.

Don't we already do that? We do check we can write through the vma and
read it via the obj. That should be checking the pages do map correctly,
and are also tiled correctly. And we do check partial vs object dma
addresses.

Adding this pass to igt_vma_partial() looks redundant as you have
already established both vma point to the same obj->pages.
-Chris