Re: [PATCH v2] serial: amba-pl011: add RS485 support

[Jiri Slaby]

On 25. 06. 21, 2:15, Lino Sanfilippo wrote:
> > > +static int pl011_rs485_config(struct uart_port *port,
> > > +			      struct serial_rs485 *rs485)
> > > +{
> > > +	struct uart_amba_port *uap =
> > > +		container_of(port, struct uart_amba_port, port);
> > > +
> > > +	/* pick sane settings if the user hasn't */
> > > +	if (!!(rs485->flags & SER_RS485_RTS_ON_SEND) ==
> >
> > Why the !! in an if statement?
> >
> > > +	    !!(rs485->flags & SER_RS485_RTS_AFTER_SEND)) {
> >
> > Same here, why?
>
> This was copied from serial8250_em485_config(). But I think we can simply use
>
> 	if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
> 		rs485->flags &= ~SER_RS485_RTS_ON_SEND;
> 	else
> 		rs485->flags |= SER_RS485_RTS_ON_SEND;
>
> instead. I will adjust the code accordingly.

This is different. You want to set ON_SEND when none is set. And unset 
AFTER_SEND when both are set. In your code, when both are set, you leave 
AFTER_SEND.

regards,
--
js
suse labs