From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932690AbXCGFNN (ORCPT ); Wed, 7 Mar 2007 00:13:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932825AbXCGFNN (ORCPT ); Wed, 7 Mar 2007 00:13:13 -0500 Received: from nf-out-0910.google.com ([64.233.182.187]:31776 "EHLO nf-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932690AbXCGFNL (ORCPT ); Wed, 7 Mar 2007 00:13:11 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=o/ZWsmHlQ6vfepM8Eq7tFFGqp6bq0z50WxaUKAo2hIJesdGrW780SMDlj7l+tvVshtxpNinSa9WG4KgPJvVNxQZP20qZ7oNwJ/oC3kUhkaD0L5sqYEMgOstfg7jGaaG1ZscE2fmlIIfClqydy8NNNrIckulGpdcLApFqIFcucCw= Message-ID: <57354eff0703062113g11ca7d34o6ed82de8195353f1@mail.gmail.com> Date: Wed, 7 Mar 2007 06:13:10 +0100 From: "Oleksiy Kebkal" To: "Krzysztof Halasa" Subject: Re: should RTS init in serial core be tied to CRTSCTS Cc: "Mike Frysinger" , rmk@arm.linux.org.uk, "Linux Kernel Mailing List" , linux-serial@vger.kernel.org, "Robin Getz" In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <8bd0f97a0703011603m794e00f5x875eb68ad0db05de@mail.gmail.com> X-Google-Sender-Auth: 47730b73a7393b97 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > > shouldnt TIOCM_RTS be passed down only when the 'r' is appended to the > > boot cmdline ? > > How would it be useful? > > CRTSCTS is for CTS only (i.e., the transmission is paused when CTS is > inactive), not for RTS. DTR and RTS should be active when the port is > open even without CRTSCTS (= without handshaking), it's used for > various purposes such as providing +12V to the device (and two pins > can supply more power than one - sure, it isn't the best idea). The name of the option is not CCTS, but CRTSCTS, isn't it? So, you may not only want to pause own transmission when CTS is inactive, but to control the transmission flow from the remote side. Why should RTS be active when the port is open even without CRTSCTS? You may still assert RTS manually if it is used to provide +12V to the device. But as I understand it is not common use of this pin, isn't it? And a question is not only about supporting legacy equipment but also about embedded hardware where RTS/CTS handshaking is handshaking, not something else... -Oleksiy