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

[Jiri Slaby]

On 22. 02. 22, 7:51, Jiri Slaby wrote:
> 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.

And this comes from userspace, so should be ratelimited.

--
js
suse labs