0011-omap-serial-Fix-bug-when-using-rs485-mode.patch

From 758829a338356549be29d43fb875985333b8f013 Mon Sep 17 00:00:00 2001
From: Enrico Butera <ebutera@users.berlios.de>
Date: Tue, 17 Jan 2012 15:10:11 +0100
Subject: [PATCH 11/12] omap-serial: Fix bug when using rs485 mode.

Rebased patch from Javier Martinez Canillas [1]:

After finishing to transmit in rs485 mode the UART_IER, UART_OMAP_SCR and
UART_MCR_RTS values weren't updated correctly.

This had the effect that once a transmission was made from a source node in
a semi-duplex communication, the transmitter didn't allow others nodes to
transmit anymore.

If the tty was closed after it finished the transmission and re-opened to
transmit again the bug wasn't spot. Only happened if the tty was kept opened.

Also, this patch make a few cleanups to the omap-serial driver.

We only have to update the Ready-to-Send control line if the user sets the
SER_RS485_RTS_ON_SEND flag and testing inside the function is redundant.

If the user didn't set the SER_RS485_RTS_ON_SEND flag, we don't have to
update the RTS line, since is the hardware who manages this.

[1]: http://git.igep.es/?p=pub/scm/linux-omap-2.6.git;a=commit;h=ecb1bc3e28d23144c4d2bdaa41bd8379e0a8de43

Signed-off-by: Enrico Butera <ebutera@users.berlios.de>
---
 drivers/tty/serial/omap-serial.c |   44 +++++++++++++++++++-------------------
 1 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index f42fc70..12049f2 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -142,25 +142,19 @@ static inline void serial_omap_thri_mode(struct uart_omap_port *up)
 	serial_out(up, UART_OMAP_SCR, scr);
 }
 
+static inline int rts_on_send(struct uart_omap_port *up)
+{
+	return up->rs485.flags & SER_RS485_RTS_ON_SEND;
+}
 
 static inline void serial_omap_update_rts(struct uart_omap_port *up)
 {
 	unsigned char mcr = up->mcr;
-	int rts_on_send = up->rs485.flags & SER_RS485_RTS_ON_SEND;
 
-	if (up->rs485.flags & SER_RS485_ENABLED) {
-		if (up->tx_in_progress) {
-			if (rts_on_send)
-				mcr |= UART_MCR_RTS;
-			else
-				mcr &= ~UART_MCR_RTS;
-		} else {
-			if (rts_on_send)
-				mcr &= ~UART_MCR_RTS;
-			else
-				mcr |= ~UART_MCR_RTS;
-		}
-	}
+	if (up->tx_in_progress)
+		mcr |= UART_MCR_RTS;
+	else
+		mcr &= ~UART_MCR_RTS;
 
 	serial_out(up, UART_MCR, mcr);
 }
@@ -186,7 +180,8 @@ static void serial_omap_stop_tx(struct uart_port *port)
 		serial_omap_disable_ier_thri(up);
 	else {
 		up->tx_in_progress = 0;
-		serial_omap_update_rts(up);
+		if (rts_on_send(up))
+			serial_omap_update_rts(up);
 		up->tx_wait_end = 1;
 		serial_omap_thri_mode(up);
 		serial_omap_enable_ier_thri(up);
@@ -312,7 +307,8 @@ static void serial_omap_start_tx(struct uart_port *port)
 	if (up->rs485.flags & SER_RS485_ENABLED) {
 		if (!up->tx_in_progress) {
 			up->tx_in_progress = 1;
-			serial_omap_update_rts(up);
+			if (rts_on_send(up))
+				serial_omap_update_rts(up);
 		}
 		if (up->tx_wait_end) {
 			up->tx_wait_end = 0;
@@ -425,12 +421,15 @@ static inline irqreturn_t serial_omap_irq(int irq, void *dev_id)
 
 	spin_lock_irqsave(&up->port.lock, flags);
 	if (up->tx_wait_end && (iir & UART_IIR_THRI) &&
-	    __serial_omap_tx_empty(up)) {
+	    __serial_omap_tx_empty(up) &&
+	    up->rs485.flags & SER_RS485_ENABLED) {
 		up->tx_wait_end = 0;
 		up->tx_in_progress = 0;
-		serial_omap_thri_mode(up);
-		serial_omap_update_rts(up);
-		serial_omap_disable_ier_thri(up);
+		up->ier = UART_IER_RLSI | UART_IER_RDI;
+		serial_out(up, UART_IER, up->ier);
+		serial_out(up, UART_OMAP_SCR, 0);
+		if (rts_on_send(up))
+			serial_out(up, UART_MCR, up->mcr | UART_MCR_RTS);
 		spin_unlock_irqrestore(&up->port.lock, flags);
 		return IRQ_HANDLED;
 	}
@@ -510,7 +509,7 @@ static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
 
 	mcr |= up->mcr;
 
-	if (up->rs485.flags & SER_RS485_ENABLED)
+	if (up->rs485.flags & SER_RS485_ENABLED && rts_on_send(up))
 		serial_omap_update_rts(up);
 
 	serial_out(up, UART_MCR, mcr);
@@ -1126,7 +1125,8 @@ serial_omap_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
 			up->tx_wait_end = 0;
 		}
 		up->rs485 = rs485conf;
-		serial_omap_update_rts(up);
+		if (rts_on_send(up))
+			serial_omap_update_rts(up);
 		serial_omap_thri_mode(up);
 		spin_unlock_irqrestore(&up->port.lock, flags);
 
-- 
1.7.5.4