drm/i915: Introduce i915_ggtt_offset()
This little helper only exists to safely discard the upper unused 32bits
of the general 64-bit VMA address - as we know that all Global GTT
currently are less than 4GiB in size and so that the upper bits must be
zero. In many places, we use a u32 for the global GTT offset and we want
to document where we are discarding the full VMA offset.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1471254551-25805-28-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 71513b1..d6e4b65 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -272,6 +272,15 @@
return vma->active & BIT(engine);
}
+static inline u32 i915_ggtt_offset(const struct i915_vma *vma)
+{
+ GEM_BUG_ON(!i915_vma_is_ggtt(vma));
+ GEM_BUG_ON(!vma->node.allocated);
+ GEM_BUG_ON(upper_32_bits(vma->node.start));
+ GEM_BUG_ON(upper_32_bits(vma->node.start + vma->node.size - 1));
+ return lower_32_bits(vma->node.start);
+}
+
struct i915_page_dma {
struct page *page;
union {