drm/i915: support forcing the page size with lmem

For some specialised objects we might need something larger than the
regions min_page_size due to some hw restriction, and slightly more
hairy is needing something smaller with the guarantee that such objects
will never be inserted into any GTT, which is the case for the paging
structures.

This also fixes how we setup the BO page_alignment, if we later migrate
the object somewhere else. For example if the placements are {SMEM,
LMEM}, then we might get this wrong. Pushing the min_page_size behaviour
into the manager should fix this.

v2(Thomas): push the default page size behaviour into buddy_man, and let
the user override it with the page-alignment, which looks cleaner

v3: rebase on ttm sys changes

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210625103824.558481-1-matthew.auld@intel.com

1 files changed, 32 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
index be1d122574af..eb345305dc52 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c
@@ -72,11 +72,42 @@ bool __i915_gem_object_is_lmem(struct drm_i915_gem_object *obj)
 		      mr->type == INTEL_MEMORY_STOLEN_LOCAL);
 }
 
+/**
+ * __i915_gem_object_create_lmem_with_ps - Create lmem object and force the
+ * minimum page size for the backing pages.
+ * @i915: The i915 instance.
+ * @size: The size in bytes for the object. Note that we need to round the size
+ * up depending on the @page_size. The final object size can be fished out from
+ * the drm GEM object.
+ * @page_size: The requested minimum page size in bytes for this object. This is
+ * useful if we need something bigger than the regions min_page_size due to some
+ * hw restriction, or in some very specialised cases where it needs to be
+ * smaller, where the internal fragmentation cost is too great when rounding up
+ * the object size.
+ * @flags: The optional BO allocation flags.
+ *
+ * Note that this interface assumes you know what you are doing when forcing the
+ * @page_size. If this is smaller than the regions min_page_size then it can
+ * never be inserted into any GTT, otherwise it might lead to undefined
+ * behaviour.
+ *
+ * Return: The object pointer, which might be an ERR_PTR in the case of failure.
+ */
+struct drm_i915_gem_object *
+__i915_gem_object_create_lmem_with_ps(struct drm_i915_private *i915,
+				      resource_size_t size,
+				      resource_size_t page_size,
+				      unsigned int flags)
+{
+	return i915_gem_object_create_region(i915->mm.regions[INTEL_REGION_LMEM],
+					     size, page_size, flags);
+}
+
 struct drm_i915_gem_object *
 i915_gem_object_create_lmem(struct drm_i915_private *i915,
 			    resource_size_t size,
 			    unsigned int flags)
 {
 	return i915_gem_object_create_region(i915->mm.regions[INTEL_REGION_LMEM],
-					     size, flags);
+					     size, 0, flags);
 }