serial: mxs-auart: Fix baudrate calculation

commit a6040bc610554c66088fda3608ae5d6307c548e4 upstream.

The reference manual for the i.MX28 recommends to calculate the divisor
as

	divisor = (UARTCLK * 32) / baud rate, rounded to the nearest integer

, so let's do this. For a typical setup of UARTCLK = 24 MHz and baud
rate = 115200 this changes the divisor from 6666 to 6667 and so the
actual baud rate improves from 115211.521 Bd (error ≅ 0.01 %) to
115194.240 Bd (error ≅ 0.005 %).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 770454e0dfa3..07390f8c3681 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1085,7 +1085,7 @@ static void mxs_auart_settermios(struct uart_port *u,
                                         AUART_LINECTRL_BAUD_DIV_MAX);
                 baud_max = u->uartclk * 32 / AUART_LINECTRL_BAUD_DIV_MIN;
                 baud = uart_get_baud_rate(u, termios, old, baud_min, baud_max);
-                div = u->uartclk * 32 / baud;
+                div = DIV_ROUND_CLOSEST(u->uartclk * 32, baud);
         }
 
         ctrl |= AUART_LINECTRL_BAUD_DIVFRAC(div & 0x3F);