diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 5ebed3ea10ba..5dc98947375c 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -665,7 +665,16 @@ struct drm_gem_object {
 	/* dma buf exported from this GEM object */
 	struct dma_buf *export_dma_buf;
 
-	/* dma buf attachment backing this object */
+	/**
+	 * import_attach - dma buf attachment backing this object
+	 *
+	 * Any foreign dma_buf imported as a gem object has this set to the
+	 * attachment point for the device. This is invariant over the lifetime
+	 * of a gem object.
+	 *
+	 * The driver's ->gem_free_object callback is responsible for cleaning
+	 * up the dma_buf attachment and references acquired at import time.
+	 */
 	struct dma_buf_attachment *import_attach;
 };