drm/i915: Rename some warts in the VMA API

Whilst writing testcases to exercise the VMA API, some oddities came to
light, such as i915_gem_obj_lookup_or_create(). Joonas suggested
i915_vma_instance() as a neat replacement, so rename them, move them to
i915_vma.c and add some kerneldoc as a sugary bonus.

s/i915_gem_obj_to_vma/i915_vma_lookup/
s/i915_gem_obj_lookup_or_create_vma/i915_vma_instance/

Suggested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170116152131.18089-2-chris@chris-wilson.co.uk

1 files changed, 89 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index fe93ed1..87273b0 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -146,6 +146,59 @@ __i915_vma_create(struct drm_i915_gem_object *obj,
 	return vma;
 }
 
+/**
+ * i915_vma_lookup - finds a matching VMA
+ * @obj: parent &struct drm_i915_gem_object to be mapped
+ * @vm: address space in which the mapping is located
+ * @view: additional mapping requirements
+ *
+ * i915_vma_lookup() looks up an existing VMA of the @obj in the @vm with
+ * the same @view characteristics.
+ *
+ * Must be called with struct_mutex held.
+ *
+ * Returns the vma if found, or NULL.
+ */
+struct i915_vma *
+i915_vma_lookup(struct drm_i915_gem_object *obj,
+		struct i915_address_space *vm,
+		const struct i915_ggtt_view *view)
+{
+	struct rb_node *rb;
+
+	lockdep_assert_held(&obj->base.dev->struct_mutex);
+
+	rb = obj->vma_tree.rb_node;
+	while (rb) {
+		struct i915_vma *vma = rb_entry(rb, struct i915_vma, obj_node);
+		long cmp;
+
+		cmp = i915_vma_compare(vma, vm, view);
+		if (cmp == 0)
+			return vma;
+
+		if (cmp < 0)
+			rb = rb->rb_right;
+		else
+			rb = rb->rb_left;
+	}
+
+	return NULL;
+}
+
+/**
+ * i915_vma_create - creates a VMA
+ * @obj: parent &struct drm_i915_gem_object to be mapped
+ * @vm: address space in which the mapping is located
+ * @view: additional mapping requirements
+ *
+ * i915_vma_create() allocates a new VMA of the @obj in the @vm with
+ * @view characteristics.
+ *
+ * Must be called with struct_mutex held.
+ *
+ * Returns the vma if found, or an error pointer.
+ */
 struct i915_vma *
 i915_vma_create(struct drm_i915_gem_object *obj,
 		struct i915_address_space *vm,
@@ -153,12 +206,47 @@ i915_vma_create(struct drm_i915_gem_object *obj,
 {
 	lockdep_assert_held(&obj->base.dev->struct_mutex);
 	GEM_BUG_ON(view && !i915_is_ggtt(vm));
-	GEM_BUG_ON(i915_gem_obj_to_vma(obj, vm, view));
+	GEM_BUG_ON(i915_vma_lookup(obj, vm, view));
 
 	return __i915_vma_create(obj, vm, view);
 }
 
 /**
+ * i915_vma_instance - return the singleton instance of the VMA
+ * @obj: parent &struct drm_i915_gem_object to be mapped
+ * @vm: address space in which the mapping is located
+ * @view: additional mapping requirements
+ *
+ * i915_vma_instance() looks up an existing VMA of the @obj in the @vm with
+ * the same @view characteristics. If a match is not found, one is created.
+ * Once created, the VMA is kept until either the object is freed, or the
+ * address space is closed.
+ *
+ * Must be called with struct_mutex held.
+ *
+ * Returns the vma, or an error pointer.
+ */
+struct i915_vma *
+i915_vma_instance(struct drm_i915_gem_object *obj,
+		  struct i915_address_space *vm,
+		  const struct i915_ggtt_view *view)
+{
+	struct i915_vma *vma;
+
+	lockdep_assert_held(&obj->base.dev->struct_mutex);
+	GEM_BUG_ON(view && !i915_is_ggtt(vm));
+	GEM_BUG_ON(vm->closed);
+
+	vma = i915_vma_lookup(obj, vm, view);
+	if (!vma)
+		vma = i915_vma_create(obj, vm, view);
+
+	GEM_BUG_ON(!IS_ERR(vma) && i915_vma_is_closed(vma));
+	GEM_BUG_ON(!IS_ERR(vma) && i915_vma_lookup(obj, vm, view) != vma);
+	return vma;
+}
+
+/**
  * i915_vma_bind - Sets up PTEs for an VMA in it's corresponding address space.
  * @vma: VMA to map
  * @cache_level: mapping cache level