Commit 368ab68b authored by Yu Tu's avatar Yu Tu Committed by Greg Kroah-Hartman
Browse files

tty: serial: meson: Use DIV_ROUND_CLOSEST to calculate baud rates 



Due to chip process differences, chip designers recommend using baud
rates as close to and larger as possible in order to reduce clock
errors.

Signed-off-by: default avatarYu Tu <yu.tu@amlogic.com>
Reviewed-by: default avatarNeil Armstrong <narmstrong@baylibre.com>
Link: https://lore.kernel.org/r/20220407081355.13602-2-yu.tu@amlogic.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 19401e97

drivers/tty/serial/meson_uart.c

+2 −2
Original line number Diff line number Diff line
@@ -299,10 +299,10 @@ static void meson_uart_change_speed(struct uart_port *port, unsigned long baud) 
		cpu_relax();



	if (port->uartclk == 24000000) {

		val = ((port->uartclk / 3) / baud) - 1;

		val = DIV_ROUND_CLOSEST(port->uartclk / 3, baud) - 1;

		val |= AML_UART_BAUD_XTAL;

	} else {

		val = ((port->uartclk * 10 / (baud * 4) + 5) / 10) - 1;

		val =  DIV_ROUND_CLOSEST(port->uartclk / 4, baud) - 1;

	}

	val |= AML_UART_BAUD_USE;

	writel(val, port->membase + AML_UART_REG5);