[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>

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.

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;

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;
 	}

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)

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)

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)

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;
 }

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;
 	}
 

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);
 }
 
 /*

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;
 

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;
 	}
 

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;

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);

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;
 

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);
 }
 
 /*

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;
 	}
 

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;
 }
 

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);
 }
 
 /**

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;

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;
 

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;

drivers/serial/sa1100.c

@@ -145,7 +145,7 @@ static void sa1100_timeout(unsigned long data)
 /*
  * interrupts disabled on entry
  */
-static void sa1100_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void sa1100_stop_tx(struct uart_port *port)
 {
 	struct sa1100_port *sport = (struct sa1100_port *)port;
 	u32 utcr3;
@@ -158,7 +158,7 @@ static void sa1100_stop_tx(struct uart_port *port, unsigned int tty_stop)
 /*
  * interrupts may not be disabled on entry
  */
-static void sa1100_start_tx(struct uart_port *port, unsigned int tty_start)
+static void sa1100_start_tx(struct uart_port *port)
 {
 	struct sa1100_port *sport = (struct sa1100_port *)port;
 	unsigned long flags;
@@ -264,7 +264,7 @@ static void sa1100_tx_chars(struct sa1100_port *sport)
 	sa1100_mctrl_check(sport);
 
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
-		sa1100_stop_tx(&sport->port, 0);
+		sa1100_stop_tx(&sport->port);
 		return;
 	}
 
@@ -284,7 +284,7 @@ static void sa1100_tx_chars(struct sa1100_port *sport)
 		uart_write_wakeup(&sport->port);
 
 	if (uart_circ_empty(xmit))
-		sa1100_stop_tx(&sport->port, 0);
+		sa1100_stop_tx(&sport->port);
 }
 
 static irqreturn_t sa1100_int(int irq, void *dev_id, struct pt_regs *regs)

drivers/serial/serial_core.c

@@ -80,7 +80,7 @@ static void uart_stop(struct tty_struct *tty)
 	unsigned long flags;
 
 	spin_lock_irqsave(&port->lock, flags);
-	port->ops->stop_tx(port, 1);
+	port->ops->stop_tx(port);
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
@@ -91,7 +91,7 @@ static void __uart_start(struct tty_struct *tty)
 
 	if (!uart_circ_empty(&state->info->xmit) && state->info->xmit.buf &&
 	    !tty->stopped && !tty->hw_stopped)
-		port->ops->start_tx(port, 1);
+		port->ops->start_tx(port);
 }
 
 static void uart_start(struct tty_struct *tty)
@@ -542,7 +542,7 @@ static void uart_send_xchar(struct tty_struct *tty, char ch)
 		port->x_char = ch;
 		if (ch) {
 			spin_lock_irqsave(&port->lock, flags);
-			port->ops->start_tx(port, 0);
+			port->ops->start_tx(port);
 			spin_unlock_irqrestore(&port->lock, flags);
 		}
 	}
@@ -1146,7 +1146,7 @@ static void uart_set_termios(struct tty_struct *tty, struct termios *old_termios
 		spin_lock_irqsave(&state->port->lock, flags);
 		if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {
 			tty->hw_stopped = 1;
-			state->port->ops->stop_tx(state->port, 0);
+			state->port->ops->stop_tx(state->port);
 		}
 		spin_unlock_irqrestore(&state->port->lock, flags);
 	}
@@ -1869,7 +1869,7 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
 		struct uart_ops *ops = port->ops;
 
 		spin_lock_irq(&port->lock);
-		ops->stop_tx(port, 0);
+		ops->stop_tx(port);
 		ops->set_mctrl(port, 0);
 		ops->stop_rx(port);
 		spin_unlock_irq(&port->lock);
@@ -1935,7 +1935,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
 		uart_change_speed(state, NULL);
 		spin_lock_irq(&port->lock);
 		ops->set_mctrl(port, port->mctrl);
-		ops->start_tx(port, 0);
+		ops->start_tx(port);
 		spin_unlock_irq(&port->lock);
 	}
 

drivers/serial/serial_lh7a40x.c

@@ -112,13 +112,12 @@ struct uart_port_lh7a40x {
 	unsigned int statusPrev; /* Most recently read modem status */
 };
 
-static void lh7a40xuart_stop_tx (struct uart_port* port, unsigned int tty_stop)
+static void lh7a40xuart_stop_tx (struct uart_port* port)
 {
 	BIT_CLR (port, UART_R_INTEN, TxInt);
 }
 
-static void lh7a40xuart_start_tx (struct uart_port* port,
-				  unsigned int tty_start)
+static void lh7a40xuart_start_tx (struct uart_port* port)
 {
 	BIT_SET (port, UART_R_INTEN, TxInt);
 

drivers/serial/serial_txx9.c

@@ -253,7 +253,7 @@ sio_quot_set(struct uart_txx9_port *up, int quot)
 		sio_out(up, TXX9_SIBGR, 0xff | TXX9_SIBGR_BCLK_T6);
 }
 
-static void serial_txx9_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void serial_txx9_stop_tx(struct uart_port *port)
 {
 	struct uart_txx9_port *up = (struct uart_txx9_port *)port;
 	unsigned long flags;
@@ -263,7 +263,7 @@ static void serial_txx9_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	spin_unlock_irqrestore(&up->port.lock, flags);
 }
 
-static void serial_txx9_start_tx(struct uart_port *port, unsigned int tty_start)
+static void serial_txx9_start_tx(struct uart_port *port)
 {
 	struct uart_txx9_port *up = (struct uart_txx9_port *)port;
 	unsigned long flags;
@@ -372,7 +372,7 @@ static inline void transmit_chars(struct uart_txx9_port *up)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		serial_txx9_stop_tx(&up->port, 0);
+		serial_txx9_stop_tx(&up->port);
 		return;
 	}
 
@@ -389,7 +389,7 @@ static inline void transmit_chars(struct uart_txx9_port *up)
 		uart_write_wakeup(&up->port);
 
 	if (uart_circ_empty(xmit))
-		serial_txx9_stop_tx(&up->port, 0);
+		serial_txx9_stop_tx(&up->port);
 }
 
 static irqreturn_t serial_txx9_interrupt(int irq, void *dev_id, struct pt_regs *regs)

drivers/serial/sh-sci.c

@@ -79,8 +79,8 @@ static struct sci_port *serial_console_port = 0;
 #endif /* CONFIG_SERIAL_SH_SCI_CONSOLE */
 
 /* Function prototypes */
-static void sci_stop_tx(struct uart_port *port, unsigned int tty_stop);
-static void sci_start_tx(struct uart_port *port, unsigned int tty_start);
+static void sci_stop_tx(struct uart_port *port);
+static void sci_start_tx(struct uart_port *port);
 static void sci_start_rx(struct uart_port *port, unsigned int tty_start);
 static void sci_stop_rx(struct uart_port *port);
 static int sci_request_irq(struct sci_port *port);
@@ -455,7 +455,7 @@ static void sci_transmit_chars(struct uart_port *port)
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 	if (uart_circ_empty(xmit)) {
-		sci_stop_tx(port, 0);
+		sci_stop_tx(port);
 	} else {
 		local_irq_save(flags);
 		ctrl = sci_in(port, SCSCR);
@@ -900,7 +900,7 @@ static unsigned int sci_get_mctrl(struct uart_port *port)
 	return TIOCM_DTR | TIOCM_RTS | TIOCM_DSR;
 }
 
-static void sci_start_tx(struct uart_port *port, unsigned int tty_start)
+static void sci_start_tx(struct uart_port *port)
 {
 	struct sci_port *s = &sci_ports[port->line];
 
@@ -909,7 +909,7 @@ static void sci_start_tx(struct uart_port *port, unsigned int tty_start)
 	enable_irq(s->irqs[SCIx_TXI_IRQ]);
 }
 
-static void sci_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void sci_stop_tx(struct uart_port *port)
 {
 	unsigned long flags;
 	unsigned short ctrl;
@@ -978,7 +978,7 @@ static void sci_shutdown(struct uart_port *port)
 	struct sci_port *s = &sci_ports[port->line];
 
 	sci_stop_rx(port);
-	sci_stop_tx(port, 1);
+	sci_stop_tx(port);
 	sci_free_irq(s);
 
 #if defined(__H8300S__)

drivers/serial/sn_console.c

@@ -259,10 +259,9 @@ static unsigned int snp_tx_empty(struct uart_port *port)
 /**
  * snp_stop_tx - stop the transmitter - no-op for us
  * @port: Port to operat eon - we ignore - no-op function
- * @tty_stop: Set to 1 if called via uart_stop
  *
  */
-static void snp_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void snp_stop_tx(struct uart_port *port)
 {
 }
 
@@ -325,10 +324,9 @@ static void snp_stop_rx(struct uart_port *port)
 /**
  * snp_start_tx - Start transmitter
  * @port: Port to operate on
- * @tty_stop: Set to 1 if called via uart_start
  *
  */
-static void snp_start_tx(struct uart_port *port, unsigned int tty_stop)
+static void snp_start_tx(struct uart_port *port)
 {
 	if (sal_console_port.sc_ops->sal_wakeup_transmit)
 		sal_console_port.sc_ops->sal_wakeup_transmit(&sal_console_port,
@@ -615,7 +613,7 @@ static void sn_transmit_chars(struct sn_cons_port *port, int raw)
 		uart_write_wakeup(&port->sc_port);
 
 	if (uart_circ_empty(xmit))
-		snp_stop_tx(&port->sc_port, 0);	/* no-op for us */
+		snp_stop_tx(&port->sc_port);	/* no-op for us */
 }
 
 /**

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;

drivers/serial/sunsu.c

@@ -255,21 +255,27 @@ static void disable_rsa(struct uart_sunsu_port *up)
 }
 #endif /* CONFIG_SERIAL_8250_RSA */
 
-static void sunsu_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static inline void __stop_tx(struct uart_sunsu_port *p)
+{
+	if (p->ier & UART_IER_THRI) {
+		p->ier &= ~UART_IER_THRI;
+		serial_out(p, UART_IER, p->ier);
+	}
+}
+
+static void sunsu_stop_tx(struct uart_port *port)
 {
 	struct uart_sunsu_port *up = (struct uart_sunsu_port *) port;
 
-	if (up->ier & UART_IER_THRI) {
-		up->ier &= ~UART_IER_THRI;
-		serial_out(up, UART_IER, up->ier);
-	}
-	if (up->port.type == PORT_16C950 && tty_stop) {
+	__stop_tx(up);
+
+	if (up->port.type == PORT_16C950 && tty_stop /*FIXME*/) {
 		up->acr |= UART_ACR_TXDIS;
 		serial_icr_write(up, UART_ACR, up->acr);
 	}
 }
 
-static void sunsu_start_tx(struct uart_port *port, unsigned int tty_start)
+static void sunsu_start_tx(struct uart_port *port)
 {
 	struct uart_sunsu_port *up = (struct uart_sunsu_port *) port;
 
@@ -280,7 +286,7 @@ static void sunsu_start_tx(struct uart_port *port, unsigned int tty_start)
 	/*
 	 * We only do this from uart_start
 	 */
-	if (tty_start && up->port.type == PORT_16C950) {
+	if (tty_start && up->port.type == PORT_16C950 /*FIXME*/) {
 		up->acr &= ~UART_ACR_TXDIS;
 		serial_icr_write(up, UART_ACR, up->acr);
 	}
@@ -413,8 +419,12 @@ static _INLINE_ void transmit_chars(struct uart_sunsu_port *up)
 		up->port.x_char = 0;
 		return;
 	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
-		sunsu_stop_tx(&up->port, 0);
+	if (uart_tx_stopped(&up->port)) {
+		sunsu_stop_tx(&up->port);
+		return;
+	}
+	if (uart_circ_empty(xmit)) {
+		__stop_tx(up);
 		return;
 	}
 
@@ -431,7 +441,7 @@ static _INLINE_ void transmit_chars(struct uart_sunsu_port *up)
 		uart_write_wakeup(&up->port);
 
 	if (uart_circ_empty(xmit))
-		sunsu_stop_tx(&up->port, 0);
+		__stop_tx(up);
 }
 
 static _INLINE_ void check_modem_status(struct uart_sunsu_port *up)

drivers/serial/sunzilog.c

@@ -684,7 +684,7 @@ static void sunzilog_set_mctrl(struct uart_port *port, unsigned int mctrl)
 }
 
 /* The port lock is held and interrupts are disabled.  */
-static void sunzilog_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void sunzilog_stop_tx(struct uart_port *port)
 {
 	struct uart_sunzilog_port *up = (struct uart_sunzilog_port *) port;
 
@@ -692,7 +692,7 @@ static void sunzilog_stop_tx(struct uart_port *port, unsigned int tty_stop)
 }
 
 /* The port lock is held and interrupts are disabled.  */
-static void sunzilog_start_tx(struct uart_port *port, unsigned int tty_start)
+static void sunzilog_start_tx(struct uart_port *port)
 {
 	struct uart_sunzilog_port *up = (struct uart_sunzilog_port *) port;
 	struct zilog_channel __iomem *channel = ZILOG_CHANNEL_FROM_PORT(port);

drivers/serial/uart00.c

@@ -87,7 +87,7 @@
 #define UART_TX_READY(s)	(((s) & UART_TSR_TX_LEVEL_MSK) < 15)
 //#define UART_TX_EMPTY(p)	((UART_GET_FR(p) & UART00_UARTFR_TMSK) == 0)
 
-static void uart00_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void uart00_stop_tx(struct uart_port *port)
 {
 	UART_PUT_IEC(port, UART_IEC_TIE_MSK);
 }
@@ -199,7 +199,7 @@ static void uart00_tx_chars(struct uart_port *port)
 		return;
 	}
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		uart00_stop_tx(port, 0);
+		uart00_stop_tx(port);
 		return;
 	}
 
@@ -218,10 +218,10 @@ static void uart00_tx_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		uart00_stop_tx(port, 0);
+		uart00_stop_tx(port);
 }
 
-static void uart00_start_tx(struct uart_port *port, unsigned int tty_start)
+static void uart00_start_tx(struct uart_port *port)
 {
 	UART_PUT_IES(port, UART_IES_TIE_MSK);
 	uart00_tx_chars(port);

drivers/serial/v850e_uart.c

@@ -240,7 +240,7 @@ console_initcall(v850e_uart_console_init);
 
 /* TX/RX interrupt handlers.  */
 
-static void v850e_uart_stop_tx (struct uart_port *port, unsigned tty_stop);
+static void v850e_uart_stop_tx (struct uart_port *port);
 
 void v850e_uart_tx (struct uart_port *port)
 {
@@ -339,14 +339,14 @@ static unsigned v850e_uart_get_mctrl (struct uart_port *port)
 	return mctrl;
 }
 
-static void v850e_uart_start_tx (struct uart_port *port, unsigned tty_start)
+static void v850e_uart_start_tx (struct uart_port *port)
 {
 	v850e_intc_disable_irq (V850E_UART_TX_IRQ (port->line));
 	v850e_uart_tx (port);
 	v850e_intc_enable_irq (V850E_UART_TX_IRQ (port->line));
 }
 
-static void v850e_uart_stop_tx (struct uart_port *port, unsigned tty_stop)
+static void v850e_uart_stop_tx (struct uart_port *port)
 {
 	v850e_intc_disable_irq (V850E_UART_TX_IRQ (port->line));
 }

drivers/serial/vr41xx_siu.c

@@ -284,7 +284,7 @@ static unsigned int siu_get_mctrl(struct uart_port *port)
 	return mctrl;
 }
 
-static void siu_stop_tx(struct uart_port *port, unsigned int tty_stop)
+static void siu_stop_tx(struct uart_port *port)
 {
 	unsigned long flags;
 	uint8_t ier;
@@ -298,7 +298,7 @@ static void siu_stop_tx(struct uart_port *port, unsigned int tty_stop)
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
-static void siu_start_tx(struct uart_port *port, unsigned int tty_start)
+static void siu_start_tx(struct uart_port *port)
 {
 	unsigned long flags;
 	uint8_t ier;
@@ -458,7 +458,7 @@ static inline void transmit_chars(struct uart_port *port)
 	}
 
 	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		siu_stop_tx(port, 0);
+		siu_stop_tx(port);
 		return;
 	}
 
@@ -474,7 +474,7 @@ static inline void transmit_chars(struct uart_port *port)
 		uart_write_wakeup(port);
 
 	if (uart_circ_empty(xmit))
-		siu_stop_tx(port, 0);
+		siu_stop_tx(port);
 }
 
 static irqreturn_t siu_interrupt(int irq, void *dev_id, struct pt_regs *regs)

include/linux/serial_core.h

@@ -142,8 +142,8 @@ struct uart_ops {
 	unsigned int	(*tx_empty)(struct uart_port *);
 	void		(*set_mctrl)(struct uart_port *, unsigned int mctrl);
 	unsigned int	(*get_mctrl)(struct uart_port *);
-	void		(*stop_tx)(struct uart_port *, unsigned int tty_stop);
-	void		(*start_tx)(struct uart_port *, unsigned int tty_start);
+	void		(*stop_tx)(struct uart_port *);
+	void		(*start_tx)(struct uart_port *);
 	void		(*send_xchar)(struct uart_port *, char ch);
 	void		(*stop_rx)(struct uart_port *);
 	void		(*enable_ms)(struct uart_port *);
@@ -468,13 +468,13 @@ uart_handle_cts_change(struct uart_port *port, unsigned int status)
 		if (tty->hw_stopped) {
 			if (status) {
 				tty->hw_stopped = 0;
-				port->ops->start_tx(port, 0);
+				port->ops->start_tx(port);
 				uart_write_wakeup(port);
 			}
 		} else {
 			if (!status) {
 				tty->hw_stopped = 1;
-				port->ops->stop_tx(port, 0);
+				port->ops->stop_tx(port);
 			}
 		}
 	}