linux-kernel - [PATCH LINUX 1/6] tty: xuartps: Move request

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Date:	Mon, 11 Jan 2016 17:41:36 -0800
From:	Soren Brinkmann <soren.brinkmann@...inx.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>
CC:	Michal Simek <michal.simek@...inx.com>,
	<linux-serial@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	"Peter Hurley" <peter@...leysoftware.com>,
	Soren Brinkmann <soren.brinkmann@...inx.com>
Subject: [PATCH LINUX 1/6] tty: xuartps: Move request_irq to after setting up the HW

Request_irq() should be _after_ h/w programming, otherwise an
interrupt could be triggered and in-progress before the h/w has been
setup.

Reported-by: Peter Hurley <peter@...leysoftware.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@...inx.com>
---
 drivers/tty/serial/xilinx_uartps.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index db9e23eaf300..5da1c51e9e40 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -762,13 +762,9 @@ static void cdns_uart_set_termios(struct uart_port *port,
  */
 static int cdns_uart_startup(struct uart_port *port)
 {
+	int ret;
 	unsigned long flags;
-	unsigned int retval = 0, status = 0;
-
-	retval = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME,
-								(void *)port);
-	if (retval)
-		return retval;
+	unsigned int status = 0;
 
 	spin_lock_irqsave(&port->lock, flags);
 
@@ -814,15 +810,22 @@ static int cdns_uart_startup(struct uart_port *port)
 	writel(readl(port->membase + CDNS_UART_ISR_OFFSET),
 			port->membase + CDNS_UART_ISR_OFFSET);
 
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	ret = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME, port);
+	if (ret) {
+		dev_err(port->dev, "request_irq '%d' failed with %d\n",
+			port->irq, ret);
+		return ret;
+	}
+
 	/* Set the Interrupt Registers with desired interrupts */
 	writel(CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_PARITY |
 		CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN |
 		CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT,
 		port->membase + CDNS_UART_IER_OFFSET);
 
-	spin_unlock_irqrestore(&port->lock, flags);
-
-	return retval;
+	return 0;
 }
 
 /**
-- 
2.7.0.3.g497ea1e