This is a note to let you know that I've just added the patch titled
serial: mxs-auart: Fix baudrate calculation
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-mxs-auart-fix-baudrate-calculation.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a6040bc610554c66088fda3608ae5d6307c548e4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <u.kleine-koenig@xxxxxxxxxxxxxx>
Date: Mon, 20 Mar 2017 10:05:38 +0100
Subject: serial: mxs-auart: Fix baudrate calculation
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From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/mxs-auart.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1085,7 +1085,7 @@ static void mxs_auart_settermios(struct
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);
Patches currently in stable-queue which might be from u.kleine-koenig@xxxxxxxxxxxxxx are
queue-4.9/serial-mxs-auart-fix-baudrate-calculation.patch