Hi, On 01.11.23 07:49, Greg Kroah-Hartman wrote: > On Wed, Nov 01, 2023 at 02:44:04PM +0800, Crescent CY Hsieh wrote: >> Add "SER_RS422_ENABLED" flag within struct serial_rs485, so that serial >> port can switching interface into RS422 if supported by using ioctl >> command "TIOCSRS485". >> >> In case of interfaces confliction, add checks within >> uart_sanitize_serial_rs485() such that only one of RS422/RS485 is set. >> >> Signed-off-by: Crescent CY Hsieh <crescentcy.hsieh@xxxxxxxx> >> >> --- >> Changes in v2: >> - Revise the logic that checks whether RS422/RS485 are enabled >> simultaneously. >> >> v1: https://lore.kernel.org/all/20231030053632.5109-1-crescentcy.hsieh@xxxxxxxx/ >> >> --- >> drivers/tty/serial/serial_core.c | 19 +++++++++++++++++-- >> include/uapi/linux/serial.h | 4 ++++ >> 2 files changed, 21 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c >> index 831d03361..54a104c52 100644 >> --- a/drivers/tty/serial/serial_core.c >> +++ b/drivers/tty/serial/serial_core.c >> @@ -1305,7 +1305,7 @@ static int uart_get_icount(struct tty_struct *tty, >> >> #define SER_RS485_LEGACY_FLAGS (SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \ >> SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \ >> - SER_RS485_TERMINATE_BUS) >> + SER_RS485_TERMINATE_BUS | SER_RS422_ENABLED) > > A new flag is "legacy"? > >> >> static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485) >> { >> @@ -1371,11 +1371,26 @@ static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs4 >> { >> u32 supported_flags = port->rs485_supported.flags; >> >> - if (!(rs485->flags & SER_RS485_ENABLED)) { >> + if (!(rs485->flags & (SER_RS485_ENABLED | SER_RS422_ENABLED))) { >> memset(rs485, 0, sizeof(*rs485)); >> return; >> } >> >> + /* Pick sane setting if the user enables both interfaces */ >> + if (rs485->flags & SER_RS485_ENABLED && rs485->flags & SER_RS422_ENABLED) { >> + dev_warn_ratelimited(port->dev, >> + "%s (%d): Invalid serial interface setting, using RS485 instead\n", >> + port->name, port->line); > > Why is this ratelimited? What would cause lots of repeats of this? > > uart_sanitize_serial_rs485() is called when userspace sets the RS485 configuration via TIOCSRS485. So warnings in this function are ratelimited to prevent userspace from spamming the kernel log. Regards, Lino
