serial: doc: Document .throttle()

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index 61d520dea4c6e13acee78cd34f2e5297700d9585..50f3d94ed50b341e15c52cf295c123ddef397bdd 100644 (file)
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -126,6 +126,13 @@ hardware.
        Interrupts: locally disabled.
        This call must not sleep
 
+  throttle(port)
+       Notify the serial driver that input buffers for the line discipline are
+       close to full, and it should somehow signal that no more characters
+       should be sent to the serial port.
+
+       Locking: none.
+
   send_xchar(port,ch)
        Transmit a high priority character, even if the port is stopped.
        This is used to implement XON/XOFF flow control and tcflow().  If