Hi, Le 11/12/2019 à 17:29, David Engraf a écrit : > Use MCK_DIV8 when the clock divider is > 65535. Unfortunately the mode > register was already written thus the clock selection is ignored. > > Fix by writing the mode register after calculating the baudrate. > > Signed-off-by: David Engraf <david.engraf@xxxxxxxxx> It seems that this bug was introduced by: commit 5bf5635ac170 ("tty/serial: atmel: add fractional baud rate support") Could you add the "Fixes:" header ? Ludovic, could you check if this was your intent at the time ? > --- > drivers/tty/serial/atmel_serial.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c > index a8dc8af83f39..9983e2fabbac 100644 > --- a/drivers/tty/serial/atmel_serial.c > +++ b/drivers/tty/serial/atmel_serial.c > @@ -2270,9 +2270,6 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, > mode |= ATMEL_US_USMODE_NORMAL; > } > I think it's better to mo move the "Set baud rate" block here (cf bellow) > - /* 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 > @@ -2315,6 +2312,9 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios, > } > quot = cd | fp << ATMEL_US_FP_OFFSET; > > + /* set the mode, clock divisor, parity, stop bits and data size */ > + atmel_uart_writel(port, ATMEL_US_MR, mode); > + I think your patch is good, but I'll be happier if instead of moving those 2 lines here, the whole "Set the baud rate" block was moved before "atmel_uart_writel(port, ATMEL_US_MR, mode);" That's because at line 2291 the ATMEL_US_CR register is set with ATMEL_US_RTSDIS or ATMEL_US_RTSEN. And those 2 values have a different effect depending on US_MR.USART_MODE Quoting from the relase manual: RTSEN: 1: Drives RTS pin to 1 if US_MR.USART_MODE field = 2, else drives RTS pin to 0 if US_MR.USART_MODE field = 0. RTSDIS: 1: Drives RTS pin to 0 if US_MR.USART_MODE field = 2, else drives RTS pin to 1 if US_MR.USART_MODE field = 0. So, I think it's better to set the mode register before setting the control register. > if (!(port->iso7816.flags & SER_ISO7816_ENABLED)) > atmel_uart_writel(port, ATMEL_US_BRGR, quot); > atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_RSTSTA | ATMEL_US_RSTRX); > Thanks !