patch "serial: mxs-auart: Fix baudrate calculation" added to tty-linus

This is a note to let you know that I've just added the patch titled

serial: mxs-auart: Fix baudrate calculation

to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <[email protected]>
Date: Mon, 20 Mar 2017 10:05:38 +0100
Subject: serial: mxs-auart: Fix baudrate calculation
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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 %).

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

index 6989b227d134..be94246b6fcc 100644
@@ -1088,7 +1088,7 @@ static void mxs_auart_settermios(struct uart_port *u,
 					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);

2.12.1