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From: Soren Brinkmann <soren.brinkmann@xilinx.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>
Cc: Michal Simek <michal.simek@xilinx.com>,
	<linux-serial@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	"Soren Brinkmann" <soren.brinkmann@xilinx.com>
Subject: [PATCH v2 05/10] tty: xuartps: Improve startup function
Date: Wed, 4 Nov 2015 23:21:14 -0800	[thread overview]
Message-ID: <1446708079-1105-6-git-send-email-soren.brinkmann@xilinx.com> (raw)
In-Reply-To: <1446708079-1105-1-git-send-email-soren.brinkmann@xilinx.com>

The startup function is supposed to initialize the UART for receiving.
Hence, don't enable the TX part. Also, protect HW accesses with the port
lock.

Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index b7fc30639292..167e0f4bcf7a 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -755,6 +755,7 @@ static void cdns_uart_set_termios(struct uart_port *port,
  */
 static int cdns_uart_startup(struct uart_port *port)
 {
+	unsigned long flags;
 	unsigned int retval = 0, status = 0;
 
 	retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
@@ -762,6 +763,8 @@ static int cdns_uart_startup(struct uart_port *port)
 	if (retval)
 		return retval;
 
+	spin_lock_irqsave(&port->lock, flags);
+
 	/* Disable the TX and RX */
 	writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
 			port->membase + CDNS_UART_CR_OFFSET);
@@ -772,15 +775,14 @@ static int cdns_uart_startup(struct uart_port *port)
 	writel(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST,
 			port->membase + CDNS_UART_CR_OFFSET);
 
-	status = readl(port->membase + CDNS_UART_CR_OFFSET);
-
-	/* Clear the RX disable and TX disable bits and then set the TX enable
-	 * bit and RX enable bit to enable the transmitter and receiver.
+	/*
+	 * Clear the RX disable bit and then set the RX enable bit to enable
+	 * the receiver.
 	 */
-	writel((status & ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS))
-			| (CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN |
-			CDNS_UART_CR_STOPBRK),
-			port->membase + CDNS_UART_CR_OFFSET);
+	status = readl(port->membase + CDNS_UART_CR_OFFSET);
+	status &= CDNS_UART_CR_RX_DIS;
+	status |= CDNS_UART_CR_RX_EN;
+	writel(status, port->membase + CDNS_UART_CR_OFFSET);
 
 	/* Set the Mode Register with normal mode,8 data bits,1 stop bit,
 	 * no parity.
@@ -811,6 +813,8 @@ static int cdns_uart_startup(struct uart_port *port)
 		CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
 		port->membase + CDNS_UART_IER_OFFSET);
 
+	spin_unlock_irqrestore(&port->lock, flags);
+
 	return retval;
 }
 
-- 
2.6.2.3.ga463a5b


  parent reply	other threads:[~2015-11-05  7:21 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-05  7:21 [PATCH v2 00/10] tty: xuartps: Fix lock ups Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 01/10] tty: xuartps: Beautify read-modify writes Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 02/10] tty: xuartps: Use spinlock to serialize HW access Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 03/10] tty: xuartps: Always enable transmitter in start_tx Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 04/10] tty: xuartps: Clear interrupt status register in shutdown Soren Brinkmann
2015-11-05  7:21 ` Soren Brinkmann [this message]
2015-11-05  7:21 ` [PATCH v2 06/10] tty: xuartps: Keep lock for whole ISR Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 07/10] tty: xuartps: Acquire port lock for shutdown Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 08/10] tty: xuartps: Move RX path into helper function Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 09/10] tty: xuartps: Only handle RX IRQs when RX is enabled Soren Brinkmann
2015-11-05  7:21 ` [PATCH v2 10/10] tty: xuartps: Cleanup: Reformat if-else Soren Brinkmann

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