- * @param data Pointer where the value will be stored. Must not be NULL.
- * @param sdi If the key is specific to a device, this must contain a
- * pointer to the struct sr_dev_inst to be checked.
+ * @param data Pointer to a GVariant where the value will be stored. Must
+ * not be NULL. The caller is given ownership of the GVariant
+ * and must thus decrease the refcount after use. However if
+ * this function returns an error code, the field should be
+ * considered unused, and should not be unreferenced.
+ * @param sdi (optional) If the key is specific to a device, this must
+ * contain a pointer to the struct sr_dev_inst to be checked.
+ * Otherwise it must be NULL.