[PATCH 4.6 50/56] serial: mvebu-uart: free the IRQ in ->shutdown()

[Greg Kroah-Hartman]

4.6-stable review patch.  If anyone has any objections, please let me know.

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

From: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>

commit c2c1659b4f8f9e19fe82a4fd06cca4b3d59090ce upstream.

As suggested by the serial port infrastructure documentation, the IRQ is
requested in ->startup(). However, it is never freed in the ->shutdown()
hook.

With simple systems that open the serial port once for all and always
have at least one process that keep the serial port opened, there was no
problem. But with a more complicated system (*cough* systemd *cough*),
the serial port is opened/closed many times, which at some point no
processes having the serial port open at all. Due to this ->startup()
gets called again, tries to request_irq() again, which fails.

Fixes: 30530791a7a0 ("serial: mvebu-uart: initial support for Armada-3700 serial port")
Cc: Ofer Heifetz <oferh@xxxxxxxxxxx>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/tty/serial/mvebu-uart.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/tty/serial/mvebu-uart.c
+++ b/drivers/tty/serial/mvebu-uart.c
@@ -299,6 +299,8 @@ static int mvebu_uart_startup(struct uar
 static void mvebu_uart_shutdown(struct uart_port *port)
 {
 	writel(0, port->membase + UART_CTRL);
+
+	free_irq(port->irq, port);
 }
 
 static void mvebu_uart_set_termios(struct uart_port *port,