[PATCH v4 4/4] ns16550: fix ier selection

[Antony Pavlov]

The document "PC16550D Universal Asynchronous
Receiver Transmitter with FIFOs" (vers. June 1995,
http://www.national.com/ds/PC/PC16550D.pdf) states
that IER (Interrupt Enable Register) is accessible
if the bit DLAB = 0 (DLAB is bit 7 in LCR; in barebox
DLAB known as LCR_BKSE).

So before IER access we need set DLAB to 0.

Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
---
 drivers/serial/serial_ns16550.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
index 802331d..88ba836 100644
--- a/drivers/serial/serial_ns16550.c
+++ b/drivers/serial/serial_ns16550.c
@@ -140,7 +140,9 @@ static inline unsigned int ns16550_calc_divisor(struct console_device *cdev,
 static void ns16550_serial_init_port(struct console_device *cdev)
 {
 	/* initializing the device for the first time */
+	ns16550_write(cdev, 0x00, lcr); /* select ier reg */
 	ns16550_write(cdev, 0x00, ier);
+
 #ifdef CONFIG_DRIVER_SERIAL_NS16550_OMAP_EXTENSIONS
 	ns16550_write(cdev, 0x07, mdr1);	/* Disable */
 #endif
-- 
1.7.8.3