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[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>
This commit is contained in:
Russell King 2005-06-29 18:41:51 +01:00 committed by Russell King
parent 0dd7a1aed7
commit e763b90c41
1 changed files with 16 additions and 12 deletions
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28
drivers/serial/8250.c
View File

@ -993,21 +993,24 @@ static void autoconfig_irq(struct uart_8250_port *up)
up->port.irq = (irq > 0) ? irq : 0; 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) static void serial8250_stop_tx(struct uart_port *port, unsigned int tty_stop)
{ {
struct uart_8250_port *up = (struct uart_8250_port *)port; struct uart_8250_port *up = (struct uart_8250_port *)port;
if (up->ier & UART_IER_THRI) { __stop_tx(up);
up->ier &= ~UART_IER_THRI;
serial_out(up, UART_IER, up->ier);
}
/* /*
* We only do this from uart_stop - if we run out of * We really want to stop the transmitter from sending.
* characters to send, we don't want to prevent the
* FIFO from emptying.
*/ */
if (up->port.type == PORT_16C950 && tty_stop) { if (up->port.type == PORT_16C950) {
up->acr |= UART_ACR_TXDIS; up->acr |= UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr); 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); 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; up->acr &= ~UART_ACR_TXDIS;
serial_icr_write(up, UART_ACR, up->acr); serial_icr_write(up, UART_ACR, up->acr);
} }
@ -1155,7 +1159,7 @@ static _INLINE_ void transmit_chars(struct uart_8250_port *up)
return; return;
} }
if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) { if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
serial8250_stop_tx(&up->port, 0); __stop_tx(up);
return; return;
} }
@ -1174,7 +1178,7 @@ static _INLINE_ void transmit_chars(struct uart_8250_port *up)
DEBUG_INTR("THRE..."); DEBUG_INTR("THRE...");
if (uart_circ_empty(xmit)) 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) static _INLINE_ void check_modem_status(struct uart_8250_port *up)