tty_port: drop last traces of low_latency

The main purpose of tty_port::low_latency was removed in commit
a9c3f68f3cd8 (tty: Fix low_latency BUG) back in 2014. It was left in
place for drivers as an optional tune knob. But only one driver has been
using it until the previous commit. So remove this misconcept
completely, given there are no users.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-11-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

8 files changed, 1 insertions, 16 deletions

diff --git a/drivers/tty/amiserial.c b/drivers/tty/amiserial.c
index 13f63c01c589..18b78ea110ef 100644
--- a/drivers/tty/amiserial.c
+++ b/drivers/tty/amiserial.c
@@ -998,7 +998,6 @@ static int set_serial_info(struct tty_struct *tty, struct serial_struct *ss)
 	state->custom_divisor = ss->custom_divisor;
 	port->close_delay = ss->close_delay * HZ/100;
 	port->closing_wait = ss->closing_wait * HZ/100;
-	port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 
 check_and_exit:
 	if (tty_port_initialized(port)) {
@@ -1386,8 +1385,6 @@ static int rs_open(struct tty_struct *tty, struct file * filp)
 	tty->driver_data = info;
 	tty->port = port;
 
-	port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
-
 	retval = startup(tty, info);
 	if (retval) {
 		return retval;
diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
index 509d1042825a..dfe02283ed23 100644
--- a/drivers/tty/hvc/hvcs.c
+++ b/drivers/tty/hvc/hvcs.c
@@ -605,7 +605,7 @@ static int hvcs_io(struct hvcs_struct *hvcsd)
 		hvcsd->todo_mask |= HVCS_QUICK_READ;
 
 	spin_unlock_irqrestore(&hvcsd->lock, flags);
-	/* This is synch because tty->low_latency == 1 */
+	/* This is synch -- FIXME :js: it is not! */
 	if(got)
 		tty_flip_buffer_push(&hvcsd->port);
 
diff --git a/drivers/tty/ipwireless/tty.c b/drivers/tty/ipwireless/tty.c
index 23584769fc29..6dacbc5e286c 100644
--- a/drivers/tty/ipwireless/tty.c
+++ b/drivers/tty/ipwireless/tty.c
@@ -101,7 +101,6 @@ static int ipw_open(struct tty_struct *linux_tty, struct file *filp)
 
 	tty->port.tty = linux_tty;
 	linux_tty->driver_data = tty;
-	tty->port.low_latency = 1;
 
 	if (tty->tty_type == TTYTYPE_MODEM)
 		ipwireless_ppp_open(tty->network);
diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 3703987c4666..4203b64bccdb 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -1273,7 +1273,6 @@ static int mxser_set_serial_info(struct tty_struct *tty,
 				(ss->flags & ASYNC_FLAGS));
 		port->close_delay = ss->close_delay * HZ / 100;
 		port->closing_wait = ss->closing_wait * HZ / 100;
-		port->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 		if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST &&
 				(ss->baud_base != info->baud_base ||
 				ss->custom_divisor !=
diff --git a/drivers/tty/serial/ifx6x60.c b/drivers/tty/serial/ifx6x60.c
index 182e0ccd60b2..d4ef88ee22d0 100644
--- a/drivers/tty/serial/ifx6x60.c
+++ b/drivers/tty/serial/ifx6x60.c
@@ -565,9 +565,6 @@ static int ifx_port_activate(struct tty_port *port, struct tty_struct *tty)
 	/* put port data into this tty */
 	tty->driver_data = ifx_dev;
 
-	/* allows flip string push from int context */
-	port->low_latency = 1;
-
 	/* set flag to allows data transfer */
 	set_bit(IFX_SPI_STATE_IO_AVAILABLE, &ifx_dev->flags);
 
diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
index 371569a0fd00..3c92d4e01488 100644
--- a/drivers/tty/serial/max3100.c
+++ b/drivers/tty/serial/max3100.c
@@ -521,9 +521,6 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 			MAX3100_STATUS_PE | MAX3100_STATUS_FE |
 			MAX3100_STATUS_OE;
 
-	/* we are sending char from a workqueue so enable */
-	s->port.state->port.low_latency = 1;
-
 	if (s->poll_time > 0)
 		del_timer_sync(&s->timer);
 
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 828f9ad1be49..7dacdb6a8534 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -975,7 +975,6 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 	port->closing_wait    = closing_wait;
 	if (new_info->xmit_fifo_size)
 		uport->fifosize = new_info->xmit_fifo_size;
-	port->low_latency = (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;
 
  check_and_exit:
 	retval = 0;
@@ -1795,8 +1794,6 @@ static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
 	if (!uport || uport->flags & UPF_DEAD)
 		return -ENXIO;
 
-	port->low_latency = (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;
-
 	/*
 	 * Start up the serial port.
 	 */
diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index c0b384e3ed4d..644173786bf0 100644
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -672,7 +672,6 @@ static int open(struct tty_struct *tty, struct file *filp)
 	DBGINFO(("%s open, old ref count = %d\n", info->device_name, info->port.count));
 
 	mutex_lock(&info->port.mutex);
-	info->port.low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 
 	spin_lock_irqsave(&info->netlock, flags);
 	if (info->netcount) {