From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1CF0C4361B for ; Thu, 10 Dec 2020 09:22:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EED423C43 for ; Thu, 10 Dec 2020 09:22:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730983AbgLJJW7 (ORCPT ); Thu, 10 Dec 2020 04:22:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:36582 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728235AbgLJJW6 (ORCPT ); Thu, 10 Dec 2020 04:22:58 -0500 Date: Thu, 10 Dec 2020 10:06:11 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1607592137; bh=uusQH84CvrIjsML3nBLyENRNWB4hJAGVg6Oykdnge6A=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=gMmjtcKYa0ITrJ+qrZ5wILYNFF+CT7GJVjfrk5z8Mgx3G7H23sSiJtGYlT/LYU34a lptTGGXXFGernbwdG8NfjSL5B+klBHZ52nazg/nHZMh7Ipx5wrXih6IworH6FB/8A/ 4bFjzlY5UXJ7LevC9lv4NWR+i3MMWDyYCowoN0EI= From: Greg Kroah-Hartman To: Mychaela Falconia Cc: Johan Hovold , Jiri Slaby , "Mychaela N . Falconia" , linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/7] tty: add flag to suppress ready signalling on open Message-ID: References: <20201202113942.27024-1-johan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 09, 2020 at 02:49:45PM -0800, Mychaela Falconia wrote: > Greg K-H wrote: > > > I think we need more review for the rest of the series. This does > > change the way serial ports work in a non-traditional way (i.e. using > > sysfs instead of terminal settings). > > But the problem is that the current status quo is fundamentally broken > for those hardware devices in which DTR and/or RTS have been repurposed > for something other than modem and flow control. Right now whenever a > "cold" (never previously opened) serial port is opened for the first > time, that open action immediately and unstoppably asserts both DTR > and RTS hardware outputs, without giving userspace any opportunity to > say "no, please don't do it". Yes, this behaviour is codified in a > bunch of standards that ultimately trace back to 1970s Original UNIX, > but just because it is a standard does not make it right - this > Unix/POSIX/Linux "standard" serial port behaviour is a bug, not a > feature. Thanks for the long response, but I think you have to realize that creating a new api for something that has been "how things work" since the 1970's should not be taken lightly. No matter if it was a bug or not, changing user-visable behavior is not a trivial thing. What we come up with here has to stand the test of time of being able to be supported properly for the next 40+ years. thanks, greg k-h