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authorRussell King <rmk@dyn-67.arm.linux.org.uk>2005-06-29 21:41:51 +0400
committerRussell King <rmk+kernel@arm.linux.org.uk>2005-06-29 21:41:51 +0400
commite763b90c41563a0f8258d379fe71a9a1f1fa5445 (patch)
tree0f20763191d255c5291f31f62ad80f41410f6222
parent0dd7a1aed7c34a39917c4faf75b4230c169e809b (diff)
downloadlinux-e763b90c41563a0f8258d379fe71a9a1f1fa5445.tar.xz
[PATCH] Serial: Disable OX950 transmitter for flow control
Disable the transmitter whenever we want to prevent characters being transmitted by flow control. However, if we run out of characters to send and want to only disable the TX interrupt, allow that scenario. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--drivers/serial/8250.c28
1 files changed, 16 insertions, 12 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index b53b53bb1475..429994d5bc8b 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -993,21 +993,24 @@ static void autoconfig_irq(struct uart_8250_port *up)
up->port.irq = (irq > 0) ? irq : 0;
}
+static inline void __stop_tx(struct uart_8250_port *p)
+{
+ if (p->ier & UART_IER_THRI) {
+ p->ier &= ~UART_IER_THRI;
+ serial_out(p, UART_IER, p->ier);
+ }
+}
+
static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
- if (up->ier & UART_IER_THRI) {
- up->ier &= ~UART_IER_THRI;
- serial_out(up, UART_IER, up->ier);
- }
+ __stop_tx(up);
/*
- * We only do this from uart_stop - if we run out of
- * characters to send, we don't want to prevent the
- * FIFO from emptying.
+ * We really want to stop the transmitter from sending.
*/
- if (up->port.type == PORT_16C950 && tty_stop) {
+ if (up->port.type == PORT_16C950) {
up->acr |= UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr);
}
@@ -1031,10 +1034,11 @@ static void serial8250_start_tx(struct uart_port *port, unsigned int tty_start)
transmit_chars(up);
}
}
+
/*
- * We only do this from uart_start
+ * Re-enable the transmitter if we disabled it.
*/
- if (tty_start && up->port.type == PORT_16C950) {
+ if (up->port.type == PORT_16C950 && up->acr & UART_ACR_TXDIS) {
up->acr &= ~UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr);
}
@@ -1155,7 +1159,7 @@ 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);
+ __stop_tx(up);
return;
}
@@ -1174,7 +1178,7 @@ static _INLINE_ void transmit_chars(struct uart_8250_port *up)
DEBUG_INTR("THRE...");
if (uart_circ_empty(xmit))
- serial8250_stop_tx(&up->port, 0);
+ __stop_tx(up);
}
static _INLINE_ void check_modem_status(struct uart_8250_port *up)