linux-kernel - Re: [PATCH 0/8] serial: 8250: Add 485 emulation to 8250

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Date:   Mon, 4 Jun 2018 12:42:47 +0200
From:   Giulio Benetti <giulio.benetti@...ronovasrl.com>
To:     "Matwey V. Kornilov" <matwey@....msu.ru>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Kees Cook <keescook@...omium.org>,
        Matthias Brugger <mbrugger@...e.com>,
        Allen Pais <allen.lkml@...il.com>, Sean Young <sean@...s.org>,
        Ed Blake <ed.blake@...drel.com>,
        Stefan Potyra <Stefan.Potyra@...ktrobit.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Joshua Scott <joshua.scott@...iedtelesis.co.nz>,
        Vignesh R <vigneshr@...com>,
        Rolf Evers-Fischer <rolf.evers.fischer@...iv.com>,
        Aaron Sierra <asierra@...-inc.com>,
        Rafael Gago <rafael.gago@...il.com>,
        Joel Stanley <joel@....id.au>,
        Sean Wang <sean.wang@...iatek.com>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] serial: 8250: Add 485 emulation to 8250_dw.

Hi everybody,

Il 04/06/2018 12:34, Matwey V. Kornilov ha scritto:
> 2018-06-04 13:12 GMT+03:00 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>:
>> On Fri, 2018-06-01 at 14:40 +0200, Giulio Benetti wrote:
>>> Need to handle rs485 with 8250_dw port.
>>>
>>> Use existing em485 emulation layer for 8250 taking care to fix some
>>> bug
>>> and taking care especially of RTS_AFTER_SEND case.
>>>
>>
>> I don't see in Cc list author of rs485 code, who might be interested in
>> this.
>>
>> So, added him here.

Thanks Andy for adding in Cc an reviewing.
Dumb question: how did you find him?
I thought he was between people on get_maintainer.pl output.

>>
> 
> Hi, Andy
> 
> Nice to see you there. I will look through the code later.
> I always thought that DW has its own hardware rs485 support.

Hi Matwey,
I've checked on Synopsis Designware 8250 datasheet and it's not supported.
Here is datasheet I went through:
https://linux-sunxi.org/images/d/d2/Dw_apb_uart_db.pdf

On IER register there is not TEMT bit or something like that used in 
8250_omap.

Am I right?

Thanks everybody and
best regards

-- 
Giulio Benetti
CTO

MICRONOVA SRL
Sede: Via A. Niedda 3 - 35010 Vigonza (PD)
Tel. 049/8931563 - Fax 049/8931346
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Iscritta al Reg. Imprese di Padova N. 02663420285
Numero R.E.A. 258642

> 
>>> Giulio Benetti (8):
>>>    serial: 8250_dw: add em485 support
>>>    serial: 8250_dw: allow enable rs485 at boot time
>>>    serial: 8250: Copy em485 from port to real port.
>>>    serial: 8250: Handle case port doesn't have TEMT interrupt using
>>>      em485.
>>>    serial: 8250_dw: treat rpm suspend with -EBUSY if RS485 ON and
>>>      RTS_AFTER_SEND
>>>    serial: 8250: Copy mctrl when register port.
>>>    serial: 8250: Make em485_rts_after_send() set mctrl according to rts
>>>      state.
>>>    serial: core: Mask mctrl with TIOCM_RTS too if rs485 on and
>>>      RTS_AFTER_SEND set.
>>>
>>>   drivers/tty/serial/8250/8250.h      |  2 +-
>>>   drivers/tty/serial/8250/8250_core.c |  2 ++
>>>   drivers/tty/serial/8250/8250_dw.c   | 41
>>> ++++++++++++++++++++++++++++-
>>>   drivers/tty/serial/8250/8250_omap.c |  2 +-
>>>   drivers/tty/serial/8250/8250_port.c | 33 ++++++++++++++++-------
>>>   drivers/tty/serial/serial_core.c    | 12 ++++++++-
>>>   include/linux/serial_8250.h         |  1 +
>>>   7 files changed, 79 insertions(+), 14 deletions(-)
>>>
>>
>> --
>> Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>> Intel Finland Oy
>>
> 
> 
>