drm/amdgpu: Implement new dummy vram manager

This adds dummy vram manager to support ASICs that do not have a
dedicated or carvedout vram domain.
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c

@@ -370,6 +370,45 @@ int amdgpu_vram_mgr_query_page_status(struct amdgpu_vram_mgr *mgr,
 	return ret;
 }
 
+static void amdgpu_dummy_vram_mgr_debug(struct ttm_resource_manager *man,
+				  struct drm_printer *printer)
+{
+	DRM_DEBUG_DRIVER("Dummy vram mgr debug\n");
+}
+
+static bool amdgpu_dummy_vram_mgr_compatible(struct ttm_resource_manager *man,
+				       struct ttm_resource *res,
+				       const struct ttm_place *place,
+				       size_t size)
+{
+	DRM_DEBUG_DRIVER("Dummy vram mgr compatible\n");
+	return false;
+}
+
+static bool amdgpu_dummy_vram_mgr_intersects(struct ttm_resource_manager *man,
+				       struct ttm_resource *res,
+				       const struct ttm_place *place,
+				       size_t size)
+{
+	DRM_DEBUG_DRIVER("Dummy vram mgr intersects\n");
+	return true;
+}
+
+static void amdgpu_dummy_vram_mgr_del(struct ttm_resource_manager *man,
+				struct ttm_resource *res)
+{
+	DRM_DEBUG_DRIVER("Dummy vram mgr deleted\n");
+}
+
+static int amdgpu_dummy_vram_mgr_new(struct ttm_resource_manager *man,
+			       struct ttm_buffer_object *tbo,
+			       const struct ttm_place *place,
+			       struct ttm_resource **res)
+{
+	DRM_DEBUG_DRIVER("Dummy vram mgr new\n");
+	return -ENOSPC;
+}
+
 /**
  * amdgpu_vram_mgr_new - allocate new ranges
  *
@@ -817,6 +856,14 @@ static void amdgpu_vram_mgr_debug(struct ttm_resource_manager *man,
 	mutex_unlock(&mgr->lock);
 }
 
+static const struct ttm_resource_manager_func amdgpu_dummy_vram_mgr_func = {
+	.alloc	= amdgpu_dummy_vram_mgr_new,
+	.free	= amdgpu_dummy_vram_mgr_del,
+	.intersects = amdgpu_dummy_vram_mgr_intersects,
+	.compatible = amdgpu_dummy_vram_mgr_compatible,
+	.debug	= amdgpu_dummy_vram_mgr_debug
+};
+
 static const struct ttm_resource_manager_func amdgpu_vram_mgr_func = {
 	.alloc	= amdgpu_vram_mgr_new,
 	.free	= amdgpu_vram_mgr_del,
@@ -841,16 +888,21 @@ int amdgpu_vram_mgr_init(struct amdgpu_device *adev)
 	ttm_resource_manager_init(man, &adev->mman.bdev,
 				  adev->gmc.real_vram_size);
 
+	mutex_init(&mgr->lock);
+	INIT_LIST_HEAD(&mgr->reservations_pending);
+	INIT_LIST_HEAD(&mgr->reserved_pages);
+	mgr->default_page_size = PAGE_SIZE;
+
+	if (!adev->gmc.is_app_apu) {
 		man->func = &amdgpu_vram_mgr_func;
 
 		err = drm_buddy_init(&mgr->mm, man->size, PAGE_SIZE);
 		if (err)
 			return err;
-
-	mutex_init(&mgr->lock);
-	INIT_LIST_HEAD(&mgr->reservations_pending);
-	INIT_LIST_HEAD(&mgr->reserved_pages);
-	mgr->default_page_size = PAGE_SIZE;
+	} else {
+		man->func = &amdgpu_dummy_vram_mgr_func;
+		DRM_INFO("Setup dummy vram mgr\n");
+	}
 
 	ttm_set_driver_manager(&adev->mman.bdev, TTM_PL_VRAM, &mgr->manager);
 	ttm_resource_manager_set_used(man, true);
@@ -886,6 +938,7 @@ void amdgpu_vram_mgr_fini(struct amdgpu_device *adev)
 		drm_buddy_free_list(&mgr->mm, &rsv->allocated);
 		kfree(rsv);
 	}
+	if (!adev->gmc.is_app_apu)
 		drm_buddy_fini(&mgr->mm);
 	mutex_unlock(&mgr->lock);