[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>

34 files changed, 149 insertions, 158 deletions

diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index ac7eabbf662a..87856d3cfb67 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -111,24 +111,17 @@ hardware.
 	Interrupts: locally disabled.
 	This call must not sleep
 
-  stop_tx(port,tty_stop)
+  stop_tx(port)
 	Stop transmitting characters.  This might be due to the CTS
 	line becoming inactive or the tty layer indicating we want
-	to stop transmission.
-
-	tty_stop: 1 if this call is due to the TTY layer issuing a
-	          TTY stop to the driver (equiv to rs_stop).
+	to stop transmission due to an XOFF character.
 
 	Locking: port->lock taken.
 	Interrupts: locally disabled.
 	This call must not sleep
 
-  start_tx(port,tty_start)
-	start transmitting characters.  (incidentally, nonempty will
-	always be nonzero, and shouldn't be used - it will be dropped).
-
-	tty_start: 1 if this call was due to the TTY layer issuing
-	           a TTY start to the driver (equiv to rs_start)
+  start_tx(port)
+	start transmitting characters.
 
 	Locking: port->lock taken.
 	Interrupts: locally disabled.
diff --git a/drivers/serial/21285.c b/drivers/serial/21285.c
index 0b10169961eb..aec39fb261ca 100644
--- a/drivers/serial/21285.c
+++ b/drivers/serial/21285.c
@@ -58,8 +58,7 @@ static const char serial21285_name[] = "Footbridge UART";
  *  int((BAUD_BASE - (baud >> 1)) / baud)
  */
 
-static void
-serial21285_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void serial21285_stop_tx(struct uart_port *port)
 {
 	if (tx_enabled(port)) {
 		disable_irq(IRQ_CONTX);
@@ -67,8 +66,7 @@ serial21285_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	}
 }
 
-static void
-serial21285_start_tx(struct uart_port *port, unsigned int tty_start)
+static void serial21285_start_tx(struct uart_port *port)
 {
 	if (!tx_enabled(port)) {
 		enable_irq(IRQ_CONTX);
@@ -148,7 +146,7 @@ static irqreturn_t serial21285_tx_chars(int irq, void *dev_id, struct pt_regs *r
 		goto out;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		serial21285_stop_tx(port, 0);
+		serial21285_stop_tx(port);
 		goto out;
 	}
 
@@ -164,7 +162,7 @@ static irqreturn_t serial21285_tx_chars(int irq, void *dev_id, struct pt_regs *r
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		serial21285_stop_tx(port, 0);
+		serial21285_stop_tx(port);
 
  out:
 	return IRQ_HANDLED;
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 7e8fc7c1d4cc..cedb5f2f35cc 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1001,7 +1001,7 @@ static inline void __stop_tx(struct uart_8250_port *p)
 	}
 }
 
-static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void serial8250_stop_tx(struct uart_port *port)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
 
@@ -1018,7 +1018,7 @@ static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
 
 static void transmit_chars(struct uart_8250_port *up);
 
-static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
+static void serial8250_start_tx(struct uart_port *port)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
 
@@ -1158,7 +1158,11 @@ static _INLINE_ void transmit_chars(struct uart_8250_port *up)
 		up->port.x_char = 0;
 		return;
 	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
+	if (uart_tx_stopped(&up->port)) {
+		serial8250_stop_tx(&up->port);
+		return;
+	}
+	if (uart_circ_empty(xmit)) {
 		__stop_tx(up);
 		return;
 	}
diff --git a/drivers/serial/amba-pl010.c b/drivers/serial/amba-pl010.c
index 2884b310e54d..978e12437e61 100644
--- a/drivers/serial/amba-pl010.c
+++ b/drivers/serial/amba-pl010.c
@@ -105,7 +105,7 @@ struct uart_amba_port {
 	unsigned int		old_status;
 };
 
-static void pl010_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void pl010_stop_tx(struct uart_port *port)
 {
 	unsigned int cr;
 
@@ -114,7 +114,7 @@ static void pl010_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	UART_PUT_CR(port, cr);
 }
 
-static void pl010_start_tx(struct uart_port *port, unsigned int tty_start)
+static void pl010_start_tx(struct uart_port *port)
 {
 	unsigned int cr;
 
@@ -219,7 +219,7 @@ static void pl010_tx_chars(struct uart_port *port)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		pl010_stop_tx(port, 0);
+		pl010_stop_tx(port);
 		return;
 	}
 
@@ -236,7 +236,7 @@ static void pl010_tx_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		pl010_stop_tx(port, 0);
+		pl010_stop_tx(port);
 }
 
 static void pl010_modem_status(struct uart_port *port)
diff --git a/drivers/serial/amba-pl011.c b/drivers/serial/amba-pl011.c
index 7db88ee18f75..56071309744c 100644
--- a/drivers/serial/amba-pl011.c
+++ b/drivers/serial/amba-pl011.c
@@ -74,7 +74,7 @@ struct uart_amba_port {
 	unsigned int		old_status;
 };
 
-static void pl011_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void pl011_stop_tx(struct uart_port *port)
 {
 	struct uart_amba_port *uap = (struct uart_amba_port *)port;
 
@@ -82,7 +82,7 @@ static void pl011_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	writew(uap->im, uap->port.membase + UART011_IMSC);
 }
 
-static void pl011_start_tx(struct uart_port *port, unsigned int tty_start)
+static void pl011_start_tx(struct uart_port *port)
 {
 	struct uart_amba_port *uap = (struct uart_amba_port *)port;
 
@@ -184,7 +184,7 @@ static void pl011_tx_chars(struct uart_amba_port *uap)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&uap->port)) {
-		pl011_stop_tx(&uap->port, 0);
+		pl011_stop_tx(&uap->port);
 		return;
 	}
 
@@ -201,7 +201,7 @@ static void pl011_tx_chars(struct uart_amba_port *uap)
 		uart_write_wakeup(&uap->port);
 
 	if (uart_circ_empty(xmit))
-		pl011_stop_tx(&uap->port, 0);
+		pl011_stop_tx(&uap->port);
 }
 
 static void pl011_modem_status(struct uart_amba_port *uap)
diff --git a/drivers/serial/au1x00_uart.c b/drivers/serial/au1x00_uart.c
index 6104aeef1243..a274ebf256a1 100644
--- a/drivers/serial/au1x00_uart.c
+++ b/drivers/serial/au1x00_uart.c
@@ -200,7 +200,7 @@ static void autoconfig(struct uart_8250_port *up, unsigned int probeflags)
 	DEBUG_AUTOCONF("type=%s\n", uart_config[up->port.type].name);
 }
 
-static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void serial8250_stop_tx(struct uart_port *port)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
 
@@ -210,7 +210,7 @@ static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	}
 }
 
-static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
+static void serial8250_start_tx(struct uart_port *port)
 {
 	struct uart_8250_port *up = (struct uart_8250_port *)port;
 
@@ -337,7 +337,7 @@ static _INLINE_ void transmit_chars(struct uart_8250_port *up)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial8250_stop_tx(&up->port, 0);
+		serial8250_stop_tx(&up->port);
 		return;
 	}
 
@@ -356,7 +356,7 @@ static _INLINE_ void transmit_chars(struct uart_8250_port *up)
 	DEBUG_INTR("THRE...");
 
 	if (uart_circ_empty(xmit))
-		serial8250_stop_tx(&up->port, 0);
+		serial8250_stop_tx(&up->port);
 }
 
 static _INLINE_ void check_modem_status(struct uart_8250_port *up)
diff --git a/drivers/serial/clps711x.c b/drivers/serial/clps711x.c
index e92522b33c48..d822896b488c 100644
--- a/drivers/serial/clps711x.c
+++ b/drivers/serial/clps711x.c
@@ -69,8 +69,7 @@
 
 #define tx_enabled(port)	((port)->unused[0])
 
-static void
-clps711xuart_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void clps711xuart_stop_tx(struct uart_port *port)
 {
 	if (tx_enabled(port)) {
 		disable_irq(TX_IRQ(port));
@@ -78,8 +77,7 @@ clps711xuart_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	}
 }
 
-static void
-clps711xuart_start_tx(struct uart_port *port, unsigned int tty_start)
+static void clps711xuart_start_tx(struct uart_port *port)
 {
 	if (!tx_enabled(port)) {
 		enable_irq(TX_IRQ(port));
@@ -165,7 +163,7 @@ static irqreturn_t clps711xuart_int_tx(int irq, void *dev_id, struct pt_regs *re
 		return IRQ_HANDLED;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		clps711xuart_stop_tx(port, 0);
+		clps711xuart_stop_tx(port);
 		return IRQ_HANDLED;
 	}
 
@@ -182,7 +180,7 @@ static irqreturn_t clps711xuart_int_tx(int irq, void *dev_id, struct pt_regs *re
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		clps711xuart_stop_tx(port, 0);
+		clps711xuart_stop_tx(port);
 
 	return IRQ_HANDLED;
 }
diff --git a/drivers/serial/cpm_uart/cpm_uart_core.c b/drivers/serial/cpm_uart/cpm_uart_core.c
index d639ac92a117..282b32351d8e 100644
--- a/drivers/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/serial/cpm_uart/cpm_uart_core.c
@@ -124,7 +124,7 @@ static unsigned int cpm_uart_get_mctrl(struct uart_port *port)
 /*
  * Stop transmitter
  */
-static void cpm_uart_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void cpm_uart_stop_tx(struct uart_port *port)
 {
 	struct uart_cpm_port *pinfo = (struct uart_cpm_port *)port;
 	volatile smc_t *smcp = pinfo->smcp;
@@ -141,7 +141,7 @@ static void cpm_uart_stop_tx(struct uart_port *port, unsigned int tty_stop)
 /*
  * Start transmitter
  */
-static void cpm_uart_start_tx(struct uart_port *port, unsigned int tty_start)
+static void cpm_uart_start_tx(struct uart_port *port)
 {
 	struct uart_cpm_port *pinfo = (struct uart_cpm_port *)port;
 	volatile smc_t *smcp = pinfo->smcp;
@@ -623,7 +623,7 @@ static int cpm_uart_tx_pump(struct uart_port *port)
 	}
 
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		cpm_uart_stop_tx(port, 0);
+		cpm_uart_stop_tx(port);
 		return 0;
 	}
 
@@ -656,7 +656,7 @@ static int cpm_uart_tx_pump(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit)) {
-		cpm_uart_stop_tx(port, 0);
+		cpm_uart_stop_tx(port);
 		return 0;
 	}
 
diff --git a/drivers/serial/dz.c b/drivers/serial/dz.c
index 97824eeeafae..e63b9dffc8d7 100644
--- a/drivers/serial/dz.c
+++ b/drivers/serial/dz.c
@@ -112,7 +112,7 @@ static inline void dz_out(struct dz_port *dport, unsigned offset,
  * ------------------------------------------------------------
  */
 
-static void dz_stop_tx(struct uart_port *uport, unsigned int tty_stop)
+static void dz_stop_tx(struct uart_port *uport)
 {
 	struct dz_port *dport = (struct dz_port *)uport;
 	unsigned short tmp, mask = 1 << dport->port.line;
@@ -125,7 +125,7 @@ static void dz_stop_tx(struct uart_port *uport, unsigned int tty_stop)
 	spin_unlock_irqrestore(&dport->port.lock, flags);
 }
 
-static void dz_start_tx(struct uart_port *uport, unsigned int tty_start)
+static void dz_start_tx(struct uart_port *uport)
 {
 	struct dz_port *dport = (struct dz_port *)uport;
 	unsigned short tmp, mask = 1 << dport->port.line;
@@ -290,7 +290,7 @@ static inline void dz_transmit_chars(struct dz_port *dport)
 	}
 	/* if nothing to do or stopped or hardware stopped */
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&dport->port)) {
-		dz_stop_tx(&dport->port, 0);
+		dz_stop_tx(&dport->port);
 		return;
 	}
 
@@ -308,7 +308,7 @@ static inline void dz_transmit_chars(struct dz_port *dport)
 
 	/* Are we done */
 	if (uart_circ_empty(xmit))
-		dz_stop_tx(&dport->port, 0);
+		dz_stop_tx(&dport->port);
 }
 
 /*
@@ -440,7 +440,7 @@ static int dz_startup(struct uart_port *uport)
  */
 static void dz_shutdown(struct uart_port *uport)
 {
-	dz_stop_tx(uport, 0);
+	dz_stop_tx(uport);
 }
 
 /*
diff --git a/drivers/serial/icom.c b/drivers/serial/icom.c
index c112b32764e8..79f8df4d66b7 100644
--- a/drivers/serial/icom.c
+++ b/drivers/serial/icom.c
@@ -989,18 +989,16 @@ static unsigned int icom_get_mctrl(struct uart_port *port)
 	return result;
 }
 
-static void icom_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void icom_stop_tx(struct uart_port *port)
 {
 	unsigned char cmdReg;
 
-	if (tty_stop) {
-		trace(ICOM_PORT, "STOP", 0);
-		cmdReg = readb(&ICOM_PORT->dram->CmdReg);
-		writeb(cmdReg | CMD_HOLD_XMIT, &ICOM_PORT->dram->CmdReg);
-	}
+	trace(ICOM_PORT, "STOP", 0);
+	cmdReg = readb(&ICOM_PORT->dram->CmdReg);
+	writeb(cmdReg | CMD_HOLD_XMIT, &ICOM_PORT->dram->CmdReg);
 }
 
-static void icom_start_tx(struct uart_port *port, unsigned int tty_start)
+static void icom_start_tx(struct uart_port *port)
 {
 	unsigned char cmdReg;
 
diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index 01a8726a3f97..8861bcf84adf 100644
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -124,7 +124,7 @@ static void imx_timeout(unsigned long data)
 /*
  * interrupts disabled on entry
  */
-static void imx_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void imx_stop_tx(struct uart_port *port)
 {
 	struct imx_port *sport = (struct imx_port *)port;
 	UCR1((u32)sport->port.membase) &= ~UCR1_TXMPTYEN;
@@ -165,13 +165,13 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
 	} while (!(UTS((u32)sport->port.membase) & UTS_TXFULL));
 
 	if (uart_circ_empty(xmit))
-		imx_stop_tx(&sport->port, 0);
+		imx_stop_tx(&sport->port);
 }
 
 /*
  * interrupts disabled on entry
  */
-static void imx_start_tx(struct uart_port *port, unsigned int tty_start)
+static void imx_start_tx(struct uart_port *port)
 {
 	struct imx_port *sport = (struct imx_port *)port;
 
@@ -196,7 +196,7 @@ static irqreturn_t imx_txint(int irq, void *dev_id, struct pt_regs *regs)
 	}
 
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
-		imx_stop_tx(&sport->port, 0);
+		imx_stop_tx(&sport->port);
 		goto out;
 	}
 
diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c
index 793c3a7cbe47..0c5c96a582b3 100644
--- a/drivers/serial/ioc4_serial.c
+++ b/drivers/serial/ioc4_serial.c
@@ -2373,10 +2373,9 @@ static unsigned int ic4_tx_empty(struct uart_port *the_port)
 /**
  * ic4_stop_tx - stop the transmitter
  * @port: Port to operate on
- * @tty_stop: Set to 1 if called via uart_stop
  *
  */
-static void ic4_stop_tx(struct uart_port *the_port, unsigned int tty_stop)
+static void ic4_stop_tx(struct uart_port *the_port)
 {
 }
 
@@ -2471,10 +2470,9 @@ static unsigned int ic4_get_mctrl(struct uart_port *the_port)
 /**
  * ic4_start_tx - Start transmitter, flush any output
  * @port: Port to operate on
- * @tty_stop: Set to 1 if called via uart_start
  *
  */
-static void ic4_start_tx(struct uart_port *the_port, unsigned int tty_stop)
+static void ic4_start_tx(struct uart_port *the_port)
 {
 	struct ioc4_port *port = get_ioc4_port(the_port);
 	unsigned long flags;
diff --git a/drivers/serial/ip22zilog.c b/drivers/serial/ip22zilog.c
index ea5bf4d4daa3..ef132349f310 100644
--- a/drivers/serial/ip22zilog.c
+++ b/drivers/serial/ip22zilog.c
@@ -592,7 +592,7 @@ static void ip22zilog_set_mctrl(struct uart_port *port, unsigned int mctrl)
 }
 
 /* The port lock is held and interrupts are disabled.  */
-static void ip22zilog_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void ip22zilog_stop_tx(struct uart_port *port)
 {
 	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
 
@@ -600,7 +600,7 @@ static void ip22zilog_stop_tx(struct uart_port *port, unsigned int tty_stop)
 }
 
 /* The port lock is held and interrupts are disabled.  */
-static void ip22zilog_start_tx(struct uart_port *port, unsigned int tty_start)
+static void ip22zilog_start_tx(struct uart_port *port)
 {
 	struct uart_ip22zilog_port *up = (struct uart_ip22zilog_port *) port;
 	struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(port);
diff --git a/drivers/serial/jsm/jsm_tty.c b/drivers/serial/jsm/jsm_tty.c
index 98de2258fd06..6fa0d62d6f68 100644
--- a/drivers/serial/jsm/jsm_tty.c
+++ b/drivers/serial/jsm/jsm_tty.c
@@ -113,7 +113,7 @@ static void jsm_tty_set_mctrl(struct uart_port *port, unsigned int mctrl)
 	udelay(10);
 }
 
-static void jsm_tty_start_tx(struct uart_port *port, unsigned int tty_start)
+static void jsm_tty_start_tx(struct uart_port *port)
 {
 	struct jsm_channel *channel = (struct jsm_channel *)port;
 
@@ -125,7 +125,7 @@ static void jsm_tty_start_tx(struct uart_port *port, unsigned int tty_start)
 	jsm_printk(IOCTL, INFO, &channel->ch_bd->pci_dev, "finish\n");
 }
 
-static void jsm_tty_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void jsm_tty_stop_tx(struct uart_port *port)
 {
 	struct jsm_channel *channel = (struct jsm_channel *)port;
 
diff --git a/drivers/serial/m32r_sio.c b/drivers/serial/m32r_sio.c
index 9b50560b9d16..b0ecc7537ce5 100644
--- a/drivers/serial/m32r_sio.c
+++ b/drivers/serial/m32r_sio.c
@@ -275,7 +275,7 @@ serial_out(struct uart_sio_port *up, int offset, int value)
 	__sio_out(value, offset);
 }
 
-static void m32r_sio_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void m32r_sio_stop_tx(struct uart_port *port)
 {
 	struct uart_sio_port *up = (struct uart_sio_port *)port;
 
@@ -285,7 +285,7 @@ static void m32r_sio_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	}
 }
 
-static void m32r_sio_start_tx(struct uart_port *port, unsigned int tty_start)
+static void m32r_sio_start_tx(struct uart_port *port)
 {
 #ifdef CONFIG_SERIAL_M32R_PLDSIO
 	struct uart_sio_port *up = (struct uart_sio_port *)port;
@@ -425,7 +425,7 @@ static _INLINE_ void transmit_chars(struct uart_sio_port *up)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		m32r_sio_stop_tx(&up->port, 0);
+		m32r_sio_stop_tx(&up->port);
 		return;
 	}
 
@@ -446,7 +446,7 @@ static _INLINE_ void transmit_chars(struct uart_sio_port *up)
 	DEBUG_INTR("THRE...");
 
 	if (uart_circ_empty(xmit))
-		m32r_sio_stop_tx(&up->port, 0);
+		m32r_sio_stop_tx(&up->port);
 }
 
 /*
diff --git a/drivers/serial/mpc52xx_uart.c b/drivers/serial/mpc52xx_uart.c
index 2a5cf174ca30..a3cd0ee8486d 100644
--- a/drivers/serial/mpc52xx_uart.c
+++ b/drivers/serial/mpc52xx_uart.c
@@ -119,7 +119,7 @@ mpc52xx_uart_get_mctrl(struct uart_port *port)
 }
 
 static void 
-mpc52xx_uart_stop_tx(struct uart_port *port, unsigned int tty_stop)
+mpc52xx_uart_stop_tx(struct uart_port *port)
 {
 	/* port->lock taken by caller */
 	port->read_status_mask &= ~MPC52xx_PSC_IMR_TXRDY;
@@ -127,7 +127,7 @@ mpc52xx_uart_stop_tx(struct uart_port *port, unsigned int tty_stop)
 }
 
 static void 
-mpc52xx_uart_start_tx(struct uart_port *port, unsigned int tty_start)
+mpc52xx_uart_start_tx(struct uart_port *port)
 {
 	/* port->lock taken by caller */
 	port->read_status_mask |= MPC52xx_PSC_IMR_TXRDY;
@@ -485,7 +485,7 @@ mpc52xx_uart_int_tx_chars(struct uart_port *port)
 
 	/* Nothing to do ? */
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mpc52xx_uart_stop_tx(port,0);
+		mpc52xx_uart_stop_tx(port);
 		return 0;
 	}
 
@@ -504,7 +504,7 @@ mpc52xx_uart_int_tx_chars(struct uart_port *port)
 
 	/* Maybe we're done after all */
 	if (uart_circ_empty(xmit)) {
-		mpc52xx_uart_stop_tx(port,0);
+		mpc52xx_uart_stop_tx(port);
 		return 0;
 	}
 
diff --git a/drivers/serial/mpsc.c b/drivers/serial/mpsc.c
index e43276c6a954..efe79b1fd431 100644
--- a/drivers/serial/mpsc.c
+++ b/drivers/serial/mpsc.c
@@ -1072,18 +1072,18 @@ mpsc_get_mctrl(struct uart_port *port)
 }
 
 static void
-mpsc_stop_tx(struct uart_port *port, uint tty_start)
+mpsc_stop_tx(struct uart_port *port)
 {
 	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
 
-	pr_debug("mpsc_stop_tx[%d]: tty_start: %d\n", port->line, tty_start);
+	pr_debug("mpsc_stop_tx[%d]\n", port->line);
 
 	mpsc_freeze(pi);
 	return;
 }
 
 static void
-mpsc_start_tx(struct uart_port *port, uint tty_start)
+mpsc_start_tx(struct uart_port *port)
 {
 	struct mpsc_port_info *pi = (struct mpsc_port_info *)port;
 
@@ -1091,7 +1091,7 @@ mpsc_start_tx(struct uart_port *port, uint tty_start)
 	mpsc_copy_tx_data(pi);
 	mpsc_sdma_start_tx(pi);
 
-	pr_debug("mpsc_start_tx[%d]: tty_start: %d\n", port->line, tty_start);
+	pr_debug("mpsc_start_tx[%d]\n", port->line);
 	return;
 }
 
diff --git a/drivers/serial/mux.c b/drivers/serial/mux.c
index dadd7e19714e..189064607709 100644
--- a/drivers/serial/mux.c
+++ b/drivers/serial/mux.c
@@ -111,22 +111,20 @@ static unsigned int mux_get_mctrl(struct uart_port *port)
 /**
  * mux_stop_tx - Stop transmitting characters.
  * @port: Ptr to the uart_port.
- * @tty_stop: tty layer issue this command?
  *
  * The Serial MUX does not support this function.
  */
-static void mux_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void mux_stop_tx(struct uart_port *port)
 {
 }
 
 /**
  * mux_start_tx - Start transmitting characters.
  * @port: Ptr to the uart_port.
- * @tty_start: tty layer issue this command?
  *
  * The Serial Mux does not support this function.
  */
-static void mux_start_tx(struct uart_port *port, unsigned int tty_start)
+static void mux_start_tx(struct uart_port *port)
 {
 }
 
@@ -181,7 +179,7 @@ static void mux_write(struct uart_port *port)
 	}
 
 	if(uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		mux_stop_tx(port, 0);
+		mux_stop_tx(port);
 		return;
 	}
 
@@ -202,7 +200,7 @@ static void mux_write(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		mux_stop_tx(port, 0);
+		mux_stop_tx(port);
 }
 
 /**
diff --git a/drivers/serial/pmac_zilog.c b/drivers/serial/pmac_zilog.c
index 7db2f37532cf..5bfde99e245e 100644
--- a/drivers/serial/pmac_zilog.c
+++ b/drivers/serial/pmac_zilog.c
@@ -630,11 +630,10 @@ static unsigned int pmz_get_mctrl(struct uart_port *port)
 
 /* 
  * Stop TX side. Dealt like sunzilog at next Tx interrupt,
- * though for DMA, we will have to do a bit more. What is
- * the meaning of the tty_stop bit ? XXX
+ * though for DMA, we will have to do a bit more.
  * The port lock is held and interrupts are disabled.
  */
-static void pmz_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void pmz_stop_tx(struct uart_port *port)
 {
 	to_pmz(port)->flags |= PMACZILOG_FLAG_TX_STOPPED;
 }
@@ -643,7 +642,7 @@ static void pmz_stop_tx(struct uart_port *port, unsigned int tty_stop)
  * Kick the Tx side.
  * The port lock is held and interrupts are disabled.
  */
-static void pmz_start_tx(struct uart_port *port, unsigned int tty_start)
+static void pmz_start_tx(struct uart_port *port)
 {
 	struct uart_pmac_port *uap = to_pmz(port);
 	unsigned char status;
diff --git a/drivers/serial/pxa.c b/drivers/serial/pxa.c
index 461c81c93207..eaa0af835290 100644
--- a/drivers/serial/pxa.c
+++ b/drivers/serial/pxa.c
@@ -80,7 +80,7 @@ static void serial_pxa_enable_ms(struct uart_port *port)
 	serial_out(up, UART_IER, up->ier);
 }
 
-static void serial_pxa_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void serial_pxa_stop_tx(struct uart_port *port)
 {
 	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
 
@@ -185,7 +185,7 @@ static void transmit_chars(struct uart_pxa_port *up)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial_pxa_stop_tx(&up->port, 0);
+		serial_pxa_stop_tx(&up->port);
 		return;
 	}
 
@@ -203,10 +203,10 @@ static void transmit_chars(struct uart_pxa_port *up)
 
 
 	if (uart_circ_empty(xmit))
-		serial_pxa_stop_tx(&up->port, 0);
+		serial_pxa_stop_tx(&up->port);
 }
 
-static void serial_pxa_start_tx(struct uart_port *port, unsigned int tty_start)
+static void serial_pxa_start_tx(struct uart_port *port)
 {
 	struct uart_pxa_port *up = (struct uart_pxa_port *)port;
 
diff --git a/drivers/serial/s3c2410.c b/drivers/serial/s3c2410.c
index 7365d4b50b95..c361c6fb0809 100644
--- a/drivers/serial/s3c2410.c
+++ b/drivers/serial/s3c2410.c
@@ -246,8 +246,7 @@ static void s3c24xx_serial_rx_disable(struct uart_port *port)
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
-static void
-s3c24xx_serial_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void s3c24xx_serial_stop_tx(struct uart_port *port)
 {
 	if (tx_enabled(port)) {
 		disable_irq(TX_IRQ(port));
@@ -257,8 +256,7 @@ s3c24xx_serial_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	}
 }
 
-static void
-s3c24xx_serial_start_tx(struct uart_port *port, unsigned int tty_start)
+static void s3c24xx_serial_start_tx(struct uart_port *port)
 {
 	if (!tx_enabled(port)) {
 		if (port->flags & UPF_CONS_FLOW)
@@ -424,7 +422,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id, struct pt_regs *re
 	*/
 
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		s3c24xx_serial_stop_tx(port, 0);
+		s3c24xx_serial_stop_tx(port);
 		goto out;
 	}
 
@@ -443,7 +441,7 @@ static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id, struct pt_regs *re
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		s3c24xx_serial_stop_tx(port, 0);
+		s3c24xx_serial_stop_tx(port);
 
  out:
 	return IRQ_HANDLED;
diff --git a/drivers/serial/sa1100.c b/drivers/serial/sa1100.c
index 98641c3f5ab9..1225b14f6e9d 100644
--- a/