[PATCH 05/15] drm/i915: align the vma start to the largest gtt page size

Matthew Auld matthew.auld at intel.com
Wed May 31 11:46:42 UTC 2017


When inserting into a 48bit PPGTT we should the 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
we don't force any alignment.

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>
---
 drivers/gpu/drm/i915/i915_vma.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 1aba47024656..c355ccb01872 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -485,6 +485,18 @@ i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 		if (ret)
 			goto err_unpin;
 	} else {
+		if (i915_vm_is_48bit(vma->vm) &&
+		    obj->mm.page_sizes.sg > I915_GTT_PAGE_SIZE) {
+			unsigned int page_alignment = obj->mm.page_sizes.sg;
+
+			/* Align to the largest and hope for the best */
+			if (!is_power_of_2(page_alignment))
+				page_alignment = BIT(fls64(page_alignment)-1);
+
+			alignment = max_t(typeof(alignment), alignment,
+					  page_alignment);
+		}
+
 		ret = i915_gem_gtt_insert(vma->vm, &vma->node,
 					  size, alignment, obj->cache_level,
 					  start, end, flags);
-- 
2.9.4



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