Re: [PATCH v3] tty/serial: atmel: fix out of range clock divider handling

From: Richard Genoud
Date: Mon Dec 16 2019 - 05:03:38 EST


Le 16/12/2019 Ã 09:54, David Engraf a ÃcritÂ:
> 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@xxxxxxxxx>

Acked-by: Richard Genoud <richard.genoud@xxxxxxxxx>


> ---
> Changes since v1:
> - moves set baud rate block before setting the mode register because
> ATMEL_US_RTSDIS and ATMEL_US_RTSEN depend on ATMEL_US_MR.mode
>
> ---
> 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;
>

Thanks !