linux-kernel - Re: [PATCH v7 3/3] tty: 8250_omap: Use software emulated RS485 direction control

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Date:	Sat, 23 Jan 2016 23:38:04 +0300
From:	"Matwey V. Kornilov" <matwey@....msu.ru>
To:	Andy Shevchenko <andy.shevchenko@...il.com>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jslaby@...e.com>,
	Peter Hurley <peter@...leysoftware.com>,
	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v7 3/3] tty: 8250_omap: Use software emulated RS485
 direction control

2016-01-23 18:20 GMT+03:00 Andy Shevchenko <andy.shevchenko@...il.com>:
> On Tue, Jan 19, 2016 at 10:33 PM, Matwey V. Kornilov <matwey@....msu.ru> wrote:
>> Use software emulated RS485 direction control to provide RS485 API existed in
>> omap_serial driver. Note that 8250_omap issues interrupt on shift register
>> empty which is single prerequesite for using software emulated RS485.
>
>
>> +static int omap_8250_rs485_config(struct uart_port *port, struct serial_rs485 *rs485)
>> +{
>> +       struct uart_8250_port *up = up_to_u8250p(port);
>> +
>> +       /* Clamp the delays to [0, 100ms] */
>
> It's not exactly clamping but rather cutting extra as I can see below.
>

I took this code and the comment from
http://marc.info/?l=linux-serial&m=145264055108439&w=2

>> +       rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
>> +       rs485->delay_rts_after_send  = min(rs485->delay_rts_after_send, 100U);
>
>> +       /* Both serial8250_em485_* functions are idempotent */
>
> Better to decode what functions do you mean here.
>
>> +       if (rs485->flags & SER_RS485_ENABLED) {
>> +               int ret = serial8250_em485_init(up);
>> +               if (ret) {
>> +                       rs485->flags &= ~SER_RS485_ENABLED;
>> +                       port->rs485.flags &= ~SER_RS485_ENABLED;
>> +               }
>
>> +               return ret;
>> +       } else
>
> You have to do } else { in multi-line branches, but luckily there is
> redundant else keyword.
>
> And checkpatch.pl doesn't tell you anything?
>
>> +               serial8250_em485_destroy(up);
>> +
>> +       return 0;
>> +}
>
> --
> With Best Regards,
> Andy Shevchenko
>



-- 
With best regards,
Matwey V. Kornilov.
Sternberg Astronomical Institute, Lomonosov Moscow State University, Russia
119991, Moscow, Universitetsky pr-k 13, +7 (495) 9392382