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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Razvan Stefanescu <razvan.stefanescu@microchip.com>,
        Richard Genoud <richard.genoud@gmail.com>
Subject: [PATCH 4.19 003/187] tty/serial: atmel: Add is_half_duplex helper
Date:   Thu,  4 Apr 2019 10:45:40 +0200
Message-Id: <20190404084603.265124773@linuxfoundation.org>
In-Reply-To: <20190404084603.119654039@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Razvan Stefanescu <razvan.stefanescu@microchip.com>

commit f3040983132bf3477acd45d2452a906e67c2fec9 upstream.

Use a helper function to check that a port needs to use half duplex
communication, replacing several occurrences of multi-line bit checking.

Fixes: b389f173aaa1 ("tty/serial: atmel: RS485 half duplex w/DMA: enable RX after TX is done")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Razvan Stefanescu <razvan.stefanescu@microchip.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
 drivers/tty/serial/atmel_serial.c |   19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -225,6 +225,12 @@ static inline void atmel_uart_write_char
 	__raw_writeb(value, port->membase + ATMEL_US_THR);
 }
 
+static inline int atmel_uart_is_half_duplex(struct uart_port *port)
+{
+	return (port->rs485.flags & SER_RS485_ENABLED) &&
+		!(port->rs485.flags & SER_RS485_RX_DURING_TX);
+}
+
 #ifdef CONFIG_SERIAL_ATMEL_PDC
 static bool atmel_use_pdc_rx(struct uart_port *port)
 {
@@ -481,9 +487,9 @@ static void atmel_stop_tx(struct uart_po
 	/* Disable interrupts */
 	atmel_uart_writel(port, ATMEL_US_IDR, atmel_port->tx_done_mask);
 
-	if ((port->rs485.flags & SER_RS485_ENABLED) &&
-	    !(port->rs485.flags & SER_RS485_RX_DURING_TX))
+	if (atmel_uart_is_half_duplex(port))
 		atmel_start_rx(port);
+
 }
 
 /*
@@ -500,8 +506,7 @@ static void atmel_start_tx(struct uart_p
 		return;
 
 	if (atmel_use_pdc_tx(port) || atmel_use_dma_tx(port))
-		if ((port->rs485.flags & SER_RS485_ENABLED) &&
-		    !(port->rs485.flags & SER_RS485_RX_DURING_TX))
+		if (atmel_uart_is_half_duplex(port))
 			atmel_stop_rx(port);
 
 	if (atmel_use_pdc_tx(port))
@@ -799,8 +804,7 @@ static void atmel_complete_tx_dma(void *
 	 */
 	if (!uart_circ_empty(xmit))
 		atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
-	else if ((port->rs485.flags & SER_RS485_ENABLED) &&
-		 !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
+	else if (atmel_uart_is_half_duplex(port)) {
 		/* DMA done, stop TX, start RX for RS485 */
 		atmel_start_rx(port);
 	}
@@ -1377,8 +1381,7 @@ static void atmel_tx_pdc(struct uart_por
 		atmel_uart_writel(port, ATMEL_US_IER,
 				  atmel_port->tx_done_mask);
 	} else {
-		if ((port->rs485.flags & SER_RS485_ENABLED) &&
-		    !(port->rs485.flags & SER_RS485_RX_DURING_TX)) {
+		if (atmel_uart_is_half_duplex(port)) {
 			/* DMA done, stop TX, start RX for RS485 */
 			atmel_start_rx(port);
 		}