diff --git a/[refs] b/[refs]
index cbcc528dedcb..37c615a38fd2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 15648f154a8faea97cbe931e189cf0a57fd066f4
+refs/heads/master: 6bb0e3a59a089e23eecc0af3b6f6012b2a9affba
diff --git a/trunk/Documentation/serial/driver b/trunk/Documentation/serial/driver
index 88ad615dd338..77ba0afbe4db 100644
--- a/trunk/Documentation/serial/driver
+++ b/trunk/Documentation/serial/driver
@@ -186,6 +186,17 @@ hardware.
 	Locking: port_sem taken.
 	Interrupts: caller dependent.
 
+  flush_buffer(port)
+	Flush any write buffers, reset any DMA state and stop any
+	ongoing DMA transfers.
+
+	This will be called whenever the port->info->xmit circular
+	buffer is cleared.
+
+	Locking: port->lock taken.
+	Interrupts: locally disabled.
+	This call must not sleep
+
   set_termios(port,termios,oldtermios)
 	Change the port parameters, including word length, parity, stop
 	bits.  Update read_status_mask and ignore_status_mask to indicate
diff --git a/trunk/drivers/serial/serial_core.c b/trunk/drivers/serial/serial_core.c
index 42d2e108b679..9884bc9eecb1 100644
--- a/trunk/drivers/serial/serial_core.c
+++ b/trunk/drivers/serial/serial_core.c
@@ -573,6 +573,8 @@ static void uart_flush_buffer(struct tty_struct *tty)
 
 	spin_lock_irqsave(&port->lock, flags);
 	uart_circ_clear(&state->info->xmit);
+	if (port->ops->flush_buffer)
+		port->ops->flush_buffer(port);
 	spin_unlock_irqrestore(&port->lock, flags);
 	tty_wakeup(tty);
 }
diff --git a/trunk/include/linux/serial_core.h b/trunk/include/linux/serial_core.h
index d8f31de632c5..1d2faa6592ae 100644
--- a/trunk/include/linux/serial_core.h
+++ b/trunk/include/linux/serial_core.h
@@ -190,6 +190,7 @@ struct uart_ops {
 	void		(*break_ctl)(struct uart_port *, int ctl);
 	int		(*startup)(struct uart_port *);
 	void		(*shutdown)(struct uart_port *);
+	void		(*flush_buffer)(struct uart_port *);
 	void		(*set_termios)(struct uart_port *, struct ktermios *new,
 				       struct ktermios *old);
 	void		(*set_ldisc)(struct uart_port *);