diff mbox series

[BACKPORT,4.14.y,8/8] serial: sprd: Modify the baud rate calculation formula

Message ID b72268635867cb643912bd842f4980c5d24cb2df.1567492316.git.baolin.wang@linaro.org
State New
Headers show
Series [BACKPORT,4.14.y,1/8] drm/i915/fbdev: Actually configure untiled displays | expand

Commit Message

(Exiting) Baolin Wang Sept. 3, 2019, 7:01 a.m. UTC 
From: Lanqing Liu <lanqing.liu@unisoc.com>


When the source clock is not divisible by the expected baud rate and
the remainder is not less than half of the expected baud rate, the old
formular will round up the frequency division coefficient. This will
make the actual baud rate less than the expected value and can not meet
the external transmission requirements.

Thus this patch modifies the baud rate calculation formula to support
the serial controller output the maximum baud rate.

Signed-off-by: Lanqing Liu <lanqing.liu@unisoc.com>

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>

---
 drivers/tty/serial/sprd_serial.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
1.7.9.5
diff mbox series

Patch

diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
index e902494..72e96ab8 100644
--- a/drivers/tty/serial/sprd_serial.c
+++ b/drivers/tty/serial/sprd_serial.c
@@ -380,7 +380,7 @@  static void sprd_set_termios(struct uart_port *port,
 	/* ask the core to calculate the divisor for us */
 	baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);
 
-	quot = (unsigned int)((port->uartclk + baud / 2) / baud);
+	quot = port->uartclk / baud;
 
 	/* set data length */
 	switch (termios->c_cflag & CSIZE) {