FAILED: patch "[PATCH] tty/serial: at91: RS485 mode: 0 is valid for" failed to apply to 3.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 3.10-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 8687634b7908c42eb700e0469e110e02833611d1 Mon Sep 17 00:00:00 2001
From: Nicolas Ferre <nicolas.ferre@atmel.com>
Date: Mon, 11 May 2015 13:00:31 +0200
Subject: [PATCH] tty/serial: at91: RS485 mode: 0 is valid for
 delay_rts_after_send
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index b1fcddd6652a..2a8f528153e7 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -316,8 +316,7 @@ 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");
@@ -355,8 +354,7 @@ 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;
 	}
@@ -2062,8 +2060,7 @@ 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) */