patch "tty/serial: atmel: fix RS485 half duplex with DMA" added to tty-next

patch "tty/serial: atmel: fix RS485 half duplex with DMA" added to tty-next

[gregkh]

This is a note to let you know that I've just added the patch titled

    tty/serial: atmel: fix RS485 half duplex with DMA

to my tty git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will also be merged in the next major kernel release
during the merge window.

If you have any questions about this process, please let me know.


>From 0058f0871efe7b01c6f2b3046c68196ab73e96da Mon Sep 17 00:00:00 2001
From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Date: Sat, 28 May 2016 00:54:08 +0200
Subject: tty/serial: atmel: fix RS485 half duplex with DMA

When using DMA, half duplex doesn't work properly because rx is not stopped
before starting tx. Ensure we call atmel_stop_rx() in the DMA case.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/atmel_serial.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 857016367a7a..f887c1df23e6 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -487,19 +487,21 @@ static void atmel_start_tx(struct uart_port *port)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 
-	if (atmel_use_pdc_tx(port)) {
-		if (atmel_uart_readl(port, ATMEL_PDC_PTSR) & ATMEL_PDC_TXTEN)
-			/* The transmitter is already running.  Yes, we
-			   really need this.*/
-			return;
+	if (atmel_use_pdc_tx(port) && (atmel_uart_readl(port, ATMEL_PDC_PTSR)
+				       & ATMEL_PDC_TXTEN))
+		/* The transmitter is already running.  Yes, we
+		   really need this.*/
+		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))
 			atmel_stop_rx(port);
 
+	if (atmel_use_pdc_tx(port))
 		/* re-enable PDC transmit */
 		atmel_uart_writel(port, ATMEL_PDC_PTCR, ATMEL_PDC_TXTEN);
-	}
+
 	/* Enable interrupts */
 	atmel_uart_writel(port, ATMEL_US_IER, atmel_port->tx_done_mask);
 }
-- 
2.9.0