Re: [PATCH v3 1/9] serial: core: move RS485 configuration tasks from drivers into core

[Jiri Slaby]

On 22. 02. 22, 2:14, Lino Sanfilippo wrote:
> Several drivers that support setting the RS485 configuration via userspace
> implement one or more of the following tasks:
>
> - in case of an invalid RTS configuration (both RTS after send and RTS on
>    send set or both unset) fall back to enable RTS on send and disable RTS
>    after send
>
> - nullify the padding field of the returned serial_rs485 struct
>
> - copy the configuration into the uart port struct
>
> - limit RTS delays to 100 ms
>
> Move these tasks into the serial core to make them generic and to provide
> a consistent behaviour among all drivers.
>
> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@xxxxxx>
> ---
>   drivers/tty/serial/serial_core.c | 29 +++++++++++++++++++++++++++++
>   1 file changed, 29 insertions(+)
>
> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
> index 846192a7b4bf..2b3afe038c1c 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -42,6 +42,11 @@ static struct lock_class_key port_lock_key;
>   
>   #define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)
>   
> +/*
> + * Max time with active RTS before/after data is sent.
> + */
> +#define RS485_MAX_RTS_DELAY	100 /* msecs */
> +
>   static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
>   					struct ktermios *old_termios);
>   static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
> @@ -1282,8 +1287,32 @@ static int uart_set_rs485_config(struct uart_port *port,
>   	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
>   		return -EFAULT;
>   
> +	/* pick sane settings if the user hasn't */
> +	if (!(rs485.flags & SER_RS485_RTS_ON_SEND) ==
> +	    !(rs485.flags & SER_RS485_RTS_AFTER_SEND)) {
> +		pr_warn("invalid RTS setting, using RTS_ON_SEND instead\n");

Can't we have a device prefix here, so that everyone knows what device 
is affected? Without that, it's not that useful. At least port->name & 
port->line could be printed. The uart core uses dev_* prints, but prints 
also line as uport->dev can be NULL sometimes.

Hm, we could introduce uart_print family (to print something like what 
is in uart_report_port).

thanks,
--
js
suse labs