[Intel-gfx] [PATCH 08/21] drm/i915: align the vma start to the largest gtt page size

[Chris Wilson]

Quoting Matthew Auld (2017-09-22 18:32:39)
> For the 48b PPGTT try to align the vma start address to the required
> page size boundary to guarantee we use said page size in the gtt. If we
> are dealing with multiple page sizes, we can't guarantee anything and
> just align to the largest. For soft pinning and objects which need to be
> tightly packed into the lower 32bits we don't force any alignment.
> 
> v2: various improvements suggested by Chris
> 
> v3: use set_pages and better placement of page_sizes
> 
> Signed-off-by: Matthew Auld <matthew.auld at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>

>         } else {
> +               /* We only support huge gtt pages through the 48b PPGTT,
> +                * however we also don't want to force any alignment for
> +                * objects which need to be tightly packed into the low 32bits.
> +                */
> +               if (end > (1ULL << 32) &&

gcc prefers
if (upper_32_bits(end) && vma->page_sizes.sg)

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