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Subject[PATCH v2] tty/serial: atmel: fix out of range clock divider handling
Date
Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode
register was already written thus the clock selection is ignored.

Fix by doing the baud rate calulation before setting the mode.

Fixes: 5bf5635ac170 ("tty/serial: atmel: add fractional baud rate support")
Signed-off-by: David Engraf <david.engraf@sysgo.com>
---
drivers/tty/serial/atmel_serial.c | 43 ++++++++++++++++---------------
1 file changed, 22 insertions(+), 21 deletions(-)

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index a8dc8af83f39..1ba9bc667e13 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -2270,27 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
mode |= ATMEL_US_USMODE_NORMAL;
}

- /* set the mode, clock divisor, parity, stop bits and data size */
- atmel_uart_writel(port, ATMEL_US_MR, mode);
-
- /*
- * when switching the mode, set the RTS line state according to the
- * new mode, otherwise keep the former state
- */
- if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) {
- unsigned int rts_state;
-
- if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
- /* let the hardware control the RTS line */
- rts_state = ATMEL_US_RTSDIS;
- } else {
- /* force RTS line to low level */
- rts_state = ATMEL_US_RTSEN;
- }
-
- atmel_uart_writel(port, ATMEL_US_CR, rts_state);
- }
-
/*
* Set the baud rate:
* Fractional baudrate allows to setup output frequency more
@@ -2317,6 +2296,28 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,

if (!(port->iso7816.flags & SER_ISO7816_ENABLED))
atmel_uart_writel(port, ATMEL_US_BRGR, quot);
+
+ /* set the mode, clock divisor, parity, stop bits and data size */
+ atmel_uart_writel(port, ATMEL_US_MR, mode);
+
+ /*
+ * when switching the mode, set the RTS line state according to the
+ * new mode, otherwise keep the former state
+ */
+ if ((old_mode & ATMEL_US_USMODE) != (mode & ATMEL_US_USMODE)) {
+ unsigned int rts_state;
+
+ if ((mode & ATMEL_US_USMODE) == ATMEL_US_USMODE_HWHS) {
+ /* let the hardware control the RTS line */
+ rts_state = ATMEL_US_RTSDIS;
+ } else {
+ /* force RTS line to low level */
+ rts_state = ATMEL_US_RTSEN;
+ }
+
+ atmel_uart_writel(port, ATMEL_US_CR, rts_state);
+ }
+
atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_TXEN | ATMEL_US_RXEN);
atmel_port->tx_stopped = false;
--
2.17.1
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