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Subject[PATCH] tty/serial: at91: RS485 mode: 0 is valid for delay_rts_after_send
Date
In RS485 mode, we may want to set the delay_rts_after_send value to 0.
In the datasheet, the 0 value is said to "disable" the Transmitter Timeguard but
this is exactly the expected behavior if we want no delay...

Moreover, if the value was set to non-zero value by device-tree or earlier
ioctl command, it was impossible to change it back to zero.

Reported-by: Sami Pietikäinen <Sami.Pietikainen@wapice.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable@vger.kernel.org # 3.2+
---
drivers/tty/serial/atmel_serial.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 27dade29646b..5ca1dfb0561c 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -315,8 +315,7 @@ static int atmel_config_rs485(struct uart_port *port,
if (rs485conf->flags & SER_RS485_ENABLED) {
dev_dbg(port->dev, "Setting UART to RS485\n");
atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
- if ((rs485conf->delay_rts_after_send) > 0)
- UART_PUT_TTGR(port, rs485conf->delay_rts_after_send);
+ UART_PUT_TTGR(port, rs485conf->delay_rts_after_send);
mode |= ATMEL_US_USMODE_RS485;
} else {
dev_dbg(port->dev, "Setting UART to RS232\n");
@@ -354,8 +353,7 @@ static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)

/* override mode to RS485 if needed, otherwise keep the current mode */
if (port->rs485.flags & SER_RS485_ENABLED) {
- if ((port->rs485.delay_rts_after_send) > 0)
- UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
+ UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
mode &= ~ATMEL_US_USMODE;
mode |= ATMEL_US_USMODE_RS485;
}
@@ -2061,8 +2059,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,

/* mode */
if (port->rs485.flags & SER_RS485_ENABLED) {
- if ((port->rs485.delay_rts_after_send) > 0)
- UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
+ UART_PUT_TTGR(port, port->rs485.delay_rts_after_send);
mode |= ATMEL_US_USMODE_RS485;
} else if (termios->c_cflag & CRTSCTS) {
/* RS232 with hardware handshake (RTS/CTS) */
--
2.1.3


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