Message-ID: <1456860493.23036.133.camel@gmail.com>
Subject: Re: [PATCH v7] serial: support for 16550A serial ports on LP-8x4x
From: Sergei Ianovich <ynvich@gmail.com>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-kernel@vger.kernel.org
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>, Arnd Bergmann <arnd@arndb.de>,
        Rob Herring <robh+dt@kernel.org>, Pawel Moll <pawel.moll@arm.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Ian Campbell <ijc+devicetree@hellion.org.uk>,
        Kumar Gala <galak@codeaurora.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jslaby@suse.com>,
        Heikki Krogerus <heikki.krogerus@linux.intel.com>,
        Peter Hurley <peter@hurleysoftware.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Paul Burton <paul.burton@imgtec.com>, Mans Rullgard <mans@mansr.com>,
        Joachim Eastwood <manabian@gmail.com>,
        Scott Wood <scottwood@freescale.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
	<devicetree@vger.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>
Date: Tue, 01 Mar 2016 22:28:13 +0300
In-Reply-To: <1456854532.13244.215.camel@linux.intel.com>
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On Tue, 2016-03-01 at 19:48 +0200, Andy Shevchenko wrote:
> On Tue, 2016-03-01 at 20:14 +0300, Sergei Ianovich wrote:
> > On Tue, 2016-03-01 at 18:46 +0200, Andy Shevchenko wrote:
> > > On Tue, 2016-03-01 at 19:25 +0300, Sergei Ianovich wrote:
> > > > On Tue, 2016-03-01 at 13:06 +0200, Andy Shevchenko wrote:
> > > > > On Tue, 2016-03-01 at 00:26 +0300, Sergei Ianovich wrote:
> 
> > > So, but if you support only fixed rates, why do you care about
> > > BOTHER
> > > at all?
> > 
> > If BOTHER is defined, tty_termios_baud_rate()
> > and tty_termios_encode_baud_rate() allow non-standard baud rates. I
> > should clear it from c_cflag to indicate I don't support it.
> > 
> > > > > >  
> > > > > I think you can call this unconditionally together with case
> > > > > >
> > > > > 115200.
> > > > 
> > > > The calls are orthogonal. This one deals with the case when
> > > > BOTHER
> > > > is
> > > > defined and set, and we have non-zero rate with BOTHER, but we
> > > > have
> > > > zero rate after BOTHER is cleared. So we set 9600 as a sane
> > > > default
> > > > speed.
> 
> Maybe you just set a baud rate nearest to the one from the table in
> case of BOTHER?
> 
> In that case perhaps you have to supply +-1 to the range. That's why
> I
> asked about uart_get_baud_rate(). 
> 
> Maybe this flow will work for you
> 
> if (BOTHER)
>  clear BOTHER
>  call uart_get_baud_rate()
> 
> ?

It works well for standard rates, let it be so. If there ever is a
problem, we can fix it.