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drm/i915: Convert i915_ggtt_view to use an anonymous union

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Reading the ggtt_views is much more pleasant without the extra
characters from specifying the union (i.e. ggtt_view.partial rather than
ggtt_view.params.partial). To make this work inside i915_vma_compare()
with only a single memcmp requires us to ensure that there are no
uninitialised bytes within each branch of the union (we make sure the
structs are packed) and we need to store the size of each branch.

v4: Rewrite changelog and add comments explaining the assert.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170114002827.31315-5-chris@chris-wilson.co.uk
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
This commit is contained in:
Chris Wilson
2017-01-14 00:28:25 +00:00
parent 3bf4d57519
commit 8bab1193c1
7 changed files with 32 additions and 27 deletions
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8
drivers/gpu/drm/i915/i915_gem.c
View File

@@ -1760,10 +1760,10 @@ compute_partial_view(struct drm_i915_gem_object *obj,
chunk = roundup(chunk, tile_row_pages(obj));
view.type = I915_GGTT_VIEW_PARTIAL;
view.params.partial.offset = rounddown(page_offset, chunk);
view.params.partial.size =
view.partial.offset = rounddown(page_offset, chunk);
view.partial.size =
min_t(unsigned int, chunk,
(obj->base.size >> PAGE_SHIFT) - view.params.partial.offset);
(obj->base.size >> PAGE_SHIFT) - view.partial.offset);
/* If the partial covers the entire object, just create a normal VMA. */
if (chunk >= obj->base.size >> PAGE_SHIFT)
@@ -1879,7 +1879,7 @@ int i915_gem_fault(struct vm_area_struct *area, struct vm_fault *vmf)
/* Finally, remap it using the new GTT offset */
ret = remap_io_mapping(area,
area->vm_start + (vma->ggtt_view.params.partial.offset << PAGE_SHIFT),
area->vm_start + (vma->ggtt_view.partial.offset << PAGE_SHIFT),
(ggtt->mappable_base + vma->node.start) >> PAGE_SHIFT,
min_t(u64, vma->size, area->vm_end - area->vm_start),
&ggtt->mappable);