diff options
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/serial/8250/8250_port.c | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 554a63e4c4a0..e54de0037df4 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2225,6 +2225,23 @@ static void serial8250_set_divisor(struct uart_port *port, unsigned int baud, serial_port_out(port, 0x2, quot_frac); } +static unsigned int +serial8250_get_baud_rate(struct uart_port *port, struct ktermios *termios, + struct ktermios *old) +{ + unsigned int tolerance = port->uartclk / 100; + + /* + * Ask the core to calculate the divisor for us. + * Allow 1% tolerance at the upper limit so uart clks marginally + * slower than nominal still match standard baud rates without + * causing transmission errors. + */ + return uart_get_baud_rate(port, termios, old, + port->uartclk / 16 / 0xffff, + (port->uartclk + tolerance) / 16); +} + void serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) @@ -2236,12 +2253,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios, cval = serial8250_compute_lcr(up, termios->c_cflag); - /* - * Ask the core to calculate the divisor for us. - */ - baud = uart_get_baud_rate(port, termios, old, - port->uartclk / 16 / 0xffff, - port->uartclk / 16); + baud = serial8250_get_baud_rate(port, termios, old); quot = serial8250_get_divisor(up, baud, &frac); /* @@ -2834,9 +2846,7 @@ void serial8250_console_write(struct uart_8250_port *up, const char *s, if (port->state->port.tty && termios.c_cflag == 0) termios.c_cflag = port->state->port.tty->termios.c_cflag; - baud = uart_get_baud_rate(port, &termios, NULL, - port->uartclk / 16 / 0xffff, - port->uartclk / 16); + baud = serial8250_get_baud_rate(port, &termios, NULL); quot = serial8250_get_divisor(up, baud, &frac); serial8250_set_divisor(port, baud, quot, frac); |