[SERIAL] Clean up and fix tty transmission start/stoping

The start_tx and stop_tx methods were passed a flag to indicate
whether the start/stop was from the tty start/stop callbacks, and
some drivers used this flag to decide whether to ask the UART to
immediately stop transmission (where the UART supports such a
feature.)

There are other cases when we wish this to occur - when CTS is
lowered, or if we change from soft to hard flow control and CTS
is inactive.  In these cases, this flag was false, and we would
allow the transmitter to drain before stopping.

There is really only one case where we want to let the transmitter
drain before disabling, and that's when we run out of characters
to send.

Hence, re-jig the start_tx and stop_tx methods to eliminate this
flag, and introduce new functions for the special "disable and
allow transmitter to drain" case.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 4 insertions, 4 deletions

diff --git a/drivers/serial/sunsab.c b/drivers/serial/sunsab.c
index 8d198880756a..e971156daa60 100644
--- a/drivers/serial/sunsab.c
+++ b/drivers/serial/sunsab.c
@@ -245,7 +245,7 @@ receive_chars(struct uart_sunsab_port *up,
         return tty;
 }
 
-static void sunsab_stop_tx(struct uart_port *, unsigned int);
+static void sunsab_stop_tx(struct uart_port *);
 static void sunsab_tx_idle(struct uart_sunsab_port *);
 
 static void transmit_chars(struct uart_sunsab_port *up,
@@ -301,7 +301,7 @@ static void transmit_chars(struct uart_sunsab_port *up,
                 uart_write_wakeup(&up->port);
 
         if (uart_circ_empty(xmit))
-                sunsab_stop_tx(&up->port, 0);
+                sunsab_stop_tx(&up->port);
 }
 
 static void check_status(struct uart_sunsab_port *up,
@@ -448,7 +448,7 @@ static unsigned int sunsab_get_mctrl(struct uart_port *port)
 }
 
 /* port->lock held by caller.  */
-static void sunsab_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void sunsab_stop_tx(struct uart_port *port)
 {
         struct uart_sunsab_port *up = (struct uart_sunsab_port *) port;
 
@@ -476,7 +476,7 @@ static void sunsab_tx_idle(struct uart_sunsab_port *up)
 }
 
 /* port->lock held by caller.  */
-static void sunsab_start_tx(struct uart_port *port, unsigned int tty_start)
+static void sunsab_start_tx(struct uart_port *port)
 {
         struct uart_sunsab_port *up = (struct uart_sunsab_port *) port;
         struct circ_buf *xmit = &up->port.info->xmit;