posix: deprecate "nonblocking" method
diff --git a/documentation/pyserial_api.rst b/documentation/pyserial_api.rst
index 6e9cf20..75e19e7 100644
--- a/documentation/pyserial_api.rst
+++ b/documentation/pyserial_api.rst
@@ -485,9 +485,10 @@
:platform: Posix
- Configure the device for nonblocking operation. This can be useful if
- the port is used with :mod:`select`. Note that :attr:`timeout` must
- also be set to ``0``
+ .. deprecated:: 3.2
+ The serial port is already opened in this mode. This method is not
+ needed and going away.
+
.. method:: fileno()