From: Tobias Schramm t.schramm@manjaro.org
commit 5bfdd3c654bd879bff50c2e85e42f85ae698b42f upstream.
Commit ba47f97a18f2 ("serial: core: remove baud_rates when serial console setup") changed uart_set_options to select the correct baudrate configuration based on the absolute error between requested baudrate and available standard baudrate settings. Prior to that commit the baudrate was selected based on which predefined standard baudrate did not exceed the requested baudrate. This change of selection logic was never reflected in the atmel serial driver. Thus the comment left in the atmel serial driver is no longer accurate. Additionally the manual rounding up described in that comment and applied via (quot - 1) requests an incorrect baudrate. Since uart_set_options uses tty_termios_encode_baud_rate to determine the appropriate baudrate flags this can cause baudrate selection to fail entirely because tty_termios_encode_baud_rate will only select a baudrate if relative error between requested and selected baudrate does not exceed +/-2%. Fix that by requesting actual, exact baudrate used by the serial.
Fixes: ba47f97a18f2 ("serial: core: remove baud_rates when serial console setup") Cc: stable stable@kernel.org Signed-off-by: Tobias Schramm t.schramm@manjaro.org Acked-by: Richard Genoud richard.genoud@gmail.com Link: https://lore.kernel.org/r/20230109072940.202936-1-t.schramm@manjaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/serial/atmel_serial.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)
--- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -2538,13 +2538,7 @@ static void __init atmel_console_get_opt else if (mr == ATMEL_US_PAR_ODD) *parity = 'o';
- /* - * The serial core only rounds down when matching this to a - * supported baud rate. Make sure we don't end up slightly - * lower than one of those, as it would make us fall through - * to a much lower baud rate than we really want. - */ - *baud = port->uartclk / (16 * (quot - 1)); + *baud = port->uartclk / (16 * quot); }
static int __init atmel_console_setup(struct console *co, char *options)