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Commit 0ee51b61 authored by Nicolas Ferre's avatar Nicolas Ferre Committed by Sasha Levin
Browse files

tty/serial: at91: RS485 mode: 0 is valid for delay_rts_after_send 



[ Upstream commit 8687634b7908c42eb700e0469e110e02833611d1 ]

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: default avatarSami Pietikäinen <Sami.Pietikainen@wapice.com>
Signed-off-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable@vger.kernel.org  # 3.2+
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
parent 78ee7365

drivers/tty/serial/atmel_serial.c

+2 −5
Original line number Diff line number Diff line
@@ -311,7 +311,6 @@ void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf) 
	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);

		mode |= ATMEL_US_USMODE_RS485;

	} else {
@@ -2016,9 +2015,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, 
	mode &= ~ATMEL_US_USMODE;



	if (atmel_port->rs485.flags & SER_RS485_ENABLED) {

		if ((atmel_port->rs485.delay_rts_after_send) > 0)

			UART_PUT_TTGR(port,

					atmel_port->rs485.delay_rts_after_send);

		UART_PUT_TTGR(port, atmel_port->rs485.delay_rts_after_send);

		mode |= ATMEL_US_USMODE_RS485;

	}