Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750972AbWBQXMp (ORCPT ); Fri, 17 Feb 2006 18:12:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751478AbWBQXMp (ORCPT ); Fri, 17 Feb 2006 18:12:45 -0500 Received: from adsl-70-250-156-241.dsl.austtx.swbell.net ([70.250.156.241]:56765 "EHLO gw.microgate.com") by vger.kernel.org with ESMTP id S1750972AbWBQXMo (ORCPT ); Fri, 17 Feb 2006 18:12:44 -0500 Message-ID: <43F65824.8050204@microgate.com> Date: Fri, 17 Feb 2006 17:11:32 -0600 From: Paul Fulghum User-Agent: Mozilla Thunderbird 1.0.7 (Windows/20050923) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Russell King CC: linux@horizon.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] SIIG 8-port serial boards support References: <20060217222529.14155.qmail@science.horizon.com> <20060217223938.GA24170@flint.arm.linux.org.uk> In-Reply-To: <20060217223938.GA24170@flint.arm.linux.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1390 Lines: 32 Russell King wrote: > On Fri, Feb 17, 2006 at 05:25:29PM -0500, linux@horizon.com wrote: >>CRTSCTS CRTSHDX Handshaking >>off off None. (Computer might as well send RTS< but ignores CTS) >>on off Full-duplex RTS/CTS >>off on RS-485. CTS ignored, RTS enables transmitter. >>on on RS-232 half-duplex. RTS is request, CTS is grant. ... > Also, !CRTSCTS is most likely the state used by any existing userspace > RS485 implementations which would be using TIOCMBIC/TIOCMBIS to > manipulate the RTS signal, so having RTS manipulated in this state > would be an undesirable change of behaviour. > > Hence, I'm very much in favour of having the default flow control > method to preserve in as many ways as possible existing behaviour > for CRTSCTS. It is important to maintain the "driver doesn't touch RTS/CTS" semantics without regard to other (new) control flags. An application might read the existing termios, and modify only the bits it is aware of without verifying that new bits are zero. CFLOWXXX also maintains a free setting for future flow modes, such as: CFLOWZEN = alter RTS based on /dev/random -- Paul Fulghum Microgate Systems, Ltd - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/