linux-kernel - Re: should RTS init in serial core be tied to CRTSCTS

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Message-ID: <20070305175604.GB18548@flint.arm.linux.org.uk>
Date:	Mon, 5 Mar 2007 17:56:04 +0000
From:	Russell King <rmk+lkml@....linux.org.uk>
To:	Mike Frysinger <vapier.adi@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-serial@...r.kernel.org,
	Robin Getz <rgetz@...ckfin.uclinux.org>
Subject: Re: should RTS init in serial core be tied to CRTSCTS

On Mon, Mar 05, 2007 at 12:09:20PM -0500, Mike Frysinger wrote:
> On 3/4/07, Russell King <rmk+lkml@....linux.org.uk> wrote:
> >On Thu, Mar 01, 2007 at 07:03:02PM -0500, Mike Frysinger wrote:
> >> the console= bootcmd allows for controlling of the initial state of
> >> flow control by adding/omitting the 'r' suffix ...
> >
> >The console command *only* sets the state for the kernel's use of one
> >serial port.  It does not affect any other serial port, so tying
> >random RTS behaviours into that command line option is absolutely
> >silly.
> 
> true ... so ignoring the original motivation for change i posted, is
> it really correct for the serial core to be forcing TIOCM_RTS at uart
> startup even though the uart doesnt have CTSRTS flow control enabled ?
> in other words, my change is agnostic of the console, and is done for
> all uarts ... it should prob have a similar change in uart_shutdown()
> though ...

No idea - it's something that Linux has always done.  Neither do I have
any idea if changing it will break anyones setup.  However, since I don't
maintain serial anymore, I'm not about to start playing about with this
trying to find out.

Feel free to submit a patch to akpm to leave RTS alone when CRTSCTS is
not set.  I'd recommend that it sits in -mm for about 6 months to really
get an idea if it breaks anything.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:
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