drm/ttm: clear the ttm_tt when bo->resource is NULL

In the next few patches, when initially creating a ttm BO, the
bo->resource is NULL, and the driver is then expected to handle the
initial dummy move.  However, if this is created as a system resource
the first ttm_tt we create will always have the clear value set to
false. Previously the initial ttm_tt would be created in
ttm_bo_validate() with the clear parameter always set to true.

Signed-off-by: Matthew Auld <[email protected]>
Reviewed-by: Christian König <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Acked-by: Nirmoy Das <[email protected]>
Signed-off-by: Christian König <[email protected]>

Author: matt-auld

drivers/gpu/drm/ttm/ttm_bo.c

@@ -120,8 +120,7 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
 	bool old_use_tt, new_use_tt;
 	int ret;
 
-	old_use_tt = bo->resource &&
-		ttm_manager_type(bdev, bo->resource->mem_type)->use_tt;
+	old_use_tt = !bo->resource || ttm_manager_type(bdev, bo->resource->mem_type)->use_tt;
 	new_use_tt = ttm_manager_type(bdev, mem->mem_type)->use_tt;
 
 	ttm_bo_unmap_virtual(bo);