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

drivers/gpu/drm/i915/i915_drv.h

@@ -3374,16 +3374,6 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev,
 struct dma_buf *i915_gem_prime_export(struct drm_device *dev,
 				struct drm_gem_object *gem_obj, int flags);
 
-struct i915_vma *
-i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
-		     struct i915_address_space *vm,
-		     const struct i915_ggtt_view *view);
-
-struct i915_vma *
-i915_gem_obj_lookup_or_create_vma(struct drm_i915_gem_object *obj,
-				  struct i915_address_space *vm,
-				  const struct i915_ggtt_view *view);
-
 static inline struct i915_hw_ppgtt *
 i915_vm_to_ppgtt(struct i915_address_space *vm)
 {
@@ -3394,7 +3384,7 @@ static inline struct i915_vma *
 i915_gem_object_to_ggtt(struct drm_i915_gem_object *obj,
 			const struct i915_ggtt_view *view)
 {
-	return i915_gem_obj_to_vma(obj, &to_i915(obj->base.dev)->ggtt.base, view);
+	return i915_vma_lookup(obj, &to_i915(obj->base.dev)->ggtt.base, view);
 }
 
 /* i915_gem_fence_reg.c */

drivers/gpu/drm/i915/i915_gem.c

@@ -3679,7 +3679,7 @@ i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
 
 	lockdep_assert_held(&obj->base.dev->struct_mutex);
 
-	vma = i915_gem_obj_lookup_or_create_vma(obj, vm, view);
+	vma = i915_vma_instance(obj, vm, view);
 	if (IS_ERR(vma))
 		return vma;
 

drivers/gpu/drm/i915/i915_gem_execbuffer.c

@@ -184,7 +184,7 @@ eb_lookup_vmas(struct eb_vmas *eb,
 		 * from the (obj, vm) we don't run the risk of creating
 		 * duplicated vmas for the same vm.
 		 */
-		vma = i915_gem_obj_lookup_or_create_vma(obj, vm, NULL);
+		vma = i915_vma_instance(obj, vm, NULL);
 		if (unlikely(IS_ERR(vma))) {
 			DRM_DEBUG("Failed to lookup VMA\n");
 			ret = PTR_ERR(vma);

drivers/gpu/drm/i915/i915_gem_gtt.c

@@ -3362,51 +3362,6 @@ void i915_gem_restore_gtt_mappings(struct drm_i915_private *dev_priv)
 	i915_ggtt_invalidate(dev_priv);
 }
 
-struct i915_vma *
-i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
-		    struct i915_address_space *vm,
-		    const struct i915_ggtt_view *view)
-{
-	struct rb_node *rb;
-
-	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;
-}
-
-struct i915_vma *
-i915_gem_obj_lookup_or_create_vma(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));
-
-	vma = i915_gem_obj_to_vma(obj, vm, view);
-	if (!vma) {
-		vma = i915_vma_create(obj, vm, view);
-		GEM_BUG_ON(vma != i915_gem_obj_to_vma(obj, vm, view));
-	}
-
-	GEM_BUG_ON(i915_vma_is_closed(vma));
-	return vma;
-}
-
 static struct scatterlist *
 rotate_pages(const dma_addr_t *in, unsigned int offset,
 	     unsigned int width, unsigned int height,

drivers/gpu/drm/i915/i915_gem_stolen.c

@@ -683,7 +683,7 @@ i915_gem_object_create_stolen_for_preallocated(struct drm_i915_private *dev_priv
 	if (ret)
 		goto err;
 
-	vma = i915_gem_obj_lookup_or_create_vma(obj, &ggtt->base, NULL);
+	vma = i915_vma_instance(obj, &ggtt->base, NULL);
 	if (IS_ERR(vma)) {
 		ret = PTR_ERR(vma);
 		goto err_pages;

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,
@@ -153,11 +206,46 @@ 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

drivers/gpu/drm/i915/i915_vma.h

@@ -116,6 +116,16 @@ i915_vma_create(struct drm_i915_gem_object *obj,
 		struct i915_address_space *vm,
 		const struct i915_ggtt_view *view);
 
+struct i915_vma *
+i915_vma_lookup(struct drm_i915_gem_object *obj,
+		struct i915_address_space *vm,
+		const struct i915_ggtt_view *view);
+
+struct i915_vma *
+i915_vma_instance(struct drm_i915_gem_object *obj,
+		  struct i915_address_space *vm,
+		  const struct i915_ggtt_view *view);
+
 void i915_vma_unpin_and_release(struct i915_vma **p_vma);
 
 static inline bool i915_vma_is_ggtt(const struct i915_vma *vma)