From: Lino Sanfilippo <LinoSanfilippo@gmx.de>
To: Jiri Slaby <jirislaby@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>,
linux@armlinux.org.uk, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] serial: amba-pl011: add RS485 support
Date: Fri, 25 Jun 2021 13:21:56 +0200 [thread overview]
Message-ID: <trinity-163a08b4-6e39-4d15-bde2-815342f13fc4-1624620116191@3c-app-gmx-bs05> (raw)
In-Reply-To: <db436292-4115-0755-57d8-d63986f84453@kernel.org>
Hi,
> 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
>
Thats right, the logic has slightly changed. I thought this does not matter as long as
we make sure that exactly one of both ON_SEND or AFTER_SEND is set. We can stick with the logic
in serial8250_em485_config() (i.e. always set ON_SEND and delete AFTER_SEND in case
of an invalid setting), but I think this will require more than the four lines that we
have now (especially if we want to avoid the !!).
Thanks,
Lino
next prev parent reply other threads:[~2021-06-25 11:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-18 14:51 [PATCH v2] serial: amba-pl011: add RS485 support Lino Sanfilippo
2021-06-24 12:55 ` Greg KH
2021-06-25 0:15 ` Lino Sanfilippo
2021-06-25 6:01 ` Jiri Slaby
2021-06-25 11:21 ` Lino Sanfilippo [this message]
2021-06-26 3:41 ` Jiri Slaby
2021-06-29 9:46 ` Lino Sanfilippo
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