serial: mvebu-uart: fix calculation of clock divisor

commit 9078204 upstream.

The clock divisor should be rounded to the closest value.

Signed-off-by: Pali Rohár <pali@kernel.org>
Fixes: 68a0db1 ("serial: mvebu-uart: add function to change baudrate")
Cc: stable@vger.kernel.org # 0e4cf69 ("serial: mvebu-uart: clarify the baud rate derivation")
Link: https://lore.kernel.org/r/20210624224909.6350-2-pali@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/mvebu-uart.c

@@ -463,7 +463,7 @@ static int mvebu_uart_baud_rate_set(struct uart_port *port, unsigned int baud)
 	 * makes use of D to configure the desired baudrate.
 	 */
 	m_divisor = OSAMP_DEFAULT_DIVISOR;
-	d_divisor = DIV_ROUND_UP(port->uartclk, baud * m_divisor);
+	d_divisor = DIV_ROUND_CLOSEST(port->uartclk, baud * m_divisor);
 
 	brdv = readl(port->membase + UART_BRDV);
 	brdv &= ~BRDV_BAUD_MASK;