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From: "Matwey V. Kornilov" <matwey@sai.msu.ru>
Date: Thu, 3 Dec 2015 20:29:54 +0300
Message-ID: <CAJs94EZiyZAsNd3A+=J9VWKzBgkoZKLn-aK+vq=zO4Lpbdnz+A@mail.gmail.com>
Subject: Re: [PATCH v3 2/5] tty: Introduce SER_RS485_SOFTWARE read-only flag
 for struct serial_rs485
To: Peter Hurley <peter@hurleysoftware.com>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>,
        Greg KH <gregkh@linuxfoundation.org>, jslaby@suse.com,
        linux-kernel <linux-kernel@vger.kernel.org>,
        linux-serial@vger.kernel.org
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2015-12-03 17:41 GMT+03:00 Peter Hurley <peter@hurleysoftware.com>:
> Hi Matwey,
>
> On 12/03/2015 12:50 AM, Matwey V. Kornilov wrote:
>> I am working on v4, where I completely redesigned implementation. And
>> now I think that it is considerably better than v3.
>> It looks like the following:
>> https://github.com/matwey/linux/commits/8520_rs485_v4
>> But it is not ready yet, there is a bug somewhere.
>>
>> In the v4, each subdriver decides separately if it needs rs485
>> emulation support. Then it enables it like the following:
>> https://github.com/matwey/linux/commit/4455e425fc045713fb921ccec695fe183f1558f0
>> Before calling serial8250_rs485_emul_enabled, the driver enables
>> interrupt on empty shift register (they are always there for omap_).
>
> Looks good.
>
> Are you testing with CONFIG_SERIAL_8250_DMA=n first to simplify the
> debug effort? DMA adds a completely different tx path.

Many thanks for the advice. I've just found that the bug is not in my code =)
Even with pure 4.3.0 I cannot open /dev/ttyS5 more than once. It just
hangs on open() and the process is in S+ state.

>
> Also, before submission, please shorten the identifiers. And Greg hates
> functions returning bool so just expanded serial8250_rs485_emul_enabled()
> inline.

Am I allowed to use `re' instead of rs485_emul in names?

>
> Regards,
> Peter Hurley
>


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