From: Uwe Kleine-König Date: Mon, 20 Mar 2017 09:05:38 +0000 (+0100) Subject: serial: mxs-auart: Fix baudrate calculation X-Git-Tag: v3.2.91~36 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2a14908e68134912eeadc8f71690c52900abb371;p=pandora-kernel.git 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 Signed-off-by: Greg Kroah-Hartman [bwh: Backported to 3.2: adjust context, indentation] Signed-off-by: Ben Hutchings --- diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c index 4f224e841585..5a9cd48e511e 100644 --- a/drivers/tty/serial/mxs-auart.c +++ b/drivers/tty/serial/mxs-auart.c @@ -366,7 +366,7 @@ static void mxs_auart_settermios(struct uart_port *u, baud_min = DIV_ROUND_UP(u->uartclk * 32, 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); ctrl |= AUART_LINECTRL_BAUD_DIVINT(div >> 6);