By default, serial_core will assert DTR for compatibility. In the case DTR is
being used for flow control this should not happen.
Signed-off-by: Aristeu Rozanski <aris@xxxxxxxxxx>
---
drivers/serial/serial_core.c | 25 ++++++++++++++++++-------
include/linux/serial_core.h | 10 +++++++---
2 files changed, 25 insertions(+), 10 deletions(-)
--- linux-next.orig/drivers/serial/serial_core.c 2008-09-25 11:56:00.000000000 -0400
+++ linux-next/drivers/serial/serial_core.c 2008-09-25 12:02:43.000000000 -0400
@@ -227,7 +227,9 @@ static int uart_startup(struct uart_stat
* port is open and ready to respond.
*/
if (info->port.tty->termios->c_cflag & CBAUD) {
- uart_set_mctrl(port, TIOCM_DTR);
+ if (!(info->port.tty->termiox->x_cflag &
+ DTRXOFF))
+ uart_set_mctrl(port, TIOCM_DTR);
uart_flow_input_start(port);
}
}
@@ -1249,7 +1251,12 @@ static void uart_set_termios(struct tty_
/* Handle transition away from B0 status */
if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
- uart_set_mctrl(state->port, TIOCM_DTR);
+ /*
+ * by default, we keep DTR on all the time, except
+ * when DTR is being used for flow control
+ */
+ if (!(tty->termiox->x_cflag & DTRXOFF))
+ uart_set_mctrl(state->port, TIOCM_DTR);
if (!test_bit(TTY_THROTTLED, &tty->flags))
uart_flow_input_start(state->port);
}
@@ -1506,7 +1513,8 @@ static void uart_update_termios(struct u
* And finally enable the DTR signal.
*/
if (tty->termios->c_cflag & CBAUD) {
- uart_set_mctrl(port, TIOCM_DTR);
+ if (!(tty->termiox->x_cflag & DTRXOFF))
+ uart_set_mctrl(port, TIOCM_DTR);
uart_flow_input_start(port);
}
}
@@ -1562,7 +1570,8 @@ uart_block_til_ready(struct file *filp,
* not set RTS here - we want to make sure we catch
* the data from the modem.
*/
- if (info->port.tty->termios->c_cflag & CBAUD)
+ if (info->port.tty->termios->c_cflag & CBAUD &&
+ !(info->port.tty->termiox->x_cflag & DTRXOFF))
uart_set_mctrl(port, TIOCM_DTR);
/*
@@ -2268,9 +2277,11 @@ uart_configure_port(struct uart_driver *
* keep the DTR setting that is set in uart_set_options()
* We probably don't need a spinlock around this, but
*/
- spin_lock_irqsave(&port->lock, flags);
- port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
- spin_unlock_irqrestore(&port->lock, flags);
+ if (!(port->flags & UPF_FLOW_DTRXOFF)) {
+ spin_lock_irqsave(&port->lock, flags);
+ port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
+ spin_unlock_irqrestore(&port->lock, flags);
+ }
/*
* If this driver supports console, and it hasn't been
--- linux-next.orig/include/linux/serial_core.h 2008-09-25 12:00:55.000000000 -0400
+++ linux-next/include/linux/serial_core.h 2008-09-25 12:02:43.000000000 -0400
@@ -581,12 +581,16 @@ uart_insert_char(struct uart_port *port,
int uart_flow_output_allowed(struct uart_port *port);
+#define uart_has_hw_flow_control(p) ((p)->flags & (UPF_FLOW_DTRXOFF | \
+ UPF_FLOW_RTSXOFF | \
+ UPF_FLOW_DSRXON | \
+ UPF_FLOW_CTSXON))
/*
* UART_ENABLE_MS - determine if port should enable modem status irqs
*/
-#define UART_ENABLE_MS(port,cflag) ((port)->flags & UPF_HARDPPS_CD || \
- (cflag) & CRTSCTS || \
- !((cflag) & CLOCAL))
+#define UART_ENABLE_MS(p,cflag) ((p)->flags & UPF_HARDPPS_CD || \
+ uart_has_hw_flow_control(p) || \
+ !((cflag) & CLOCAL))
#endif
--
Aristeu
--
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