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SubjectRe: [PATCH 4/8] serial: core: sanitize RS485 delays read from device tree
On Wed, 22 Jun 2022, Lino Sanfilippo wrote:

> From: Lino Sanfilippo <l.sanfilippo@kunbus.com>
>
> When setting the RS485 configuration from userspace via TIOCSRS485 the
> delays are clamped to 100ms. Make this consistent with the values passed
> in by means of device tree parameters.
>
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
> ---
> drivers/tty/serial/serial_core.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index fa6acadd7d0c..2e9f90e73e62 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -3382,6 +3382,8 @@ int uart_get_rs485_mode(struct uart_port *port)
> rs485conf->delay_rts_after_send = 0;
> }
>
> + uart_sanitize_serial_rs485_delays(port, rs485conf);
> +
> /*
> * Clear full-duplex and enabled flags, set RTS polarity to active high
> * to get to a defined state with the following properties:
> --
> 2.36.1

While above works, if we go to this change user-visible behavior route,
uart_get_rs485_mode() could just call full uart_sanitize_serial_rs485()?

The sanitization is currently being done during probe in
uart_rs485_config() which has another challenge to tackle. The RS485
supporting UART drivers are not consistently calling it during their
probe(), only a few of them do but it would make more sense if all of them
would enter into RS485 mode w/ linux,rs485-enabled-at-boot-time being
set. However, making such change might run afoul with the expectations of
users.


--
i.

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