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 2F8D7C4361B for ; Wed, 9 Dec 2020 14:30:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE88722AAE for ; Wed, 9 Dec 2020 14:30:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732121AbgLIOaL (ORCPT ); Wed, 9 Dec 2020 09:30:11 -0500 Received: from mail.kernel.org ([198.145.29.99]:38238 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732852AbgLIO35 (ORCPT ); Wed, 9 Dec 2020 09:29:57 -0500 Date: Wed, 9 Dec 2020 15:30:33 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1607524157; bh=tGb2bsihTlzyOAC5cT78Tgjia37FE/zrr0cFrYwkh+A=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=RFTxMXqtvwtq2lG6Y9UwA7UCRNt/AA7XzOy6nK/WxCqIj+JEUlQ76Ee1KcosDHtCN IUtXCFkQL2MKqiWgc+WCXFPS9brJeRzrrp8/VuHLDXm9nGTm4LtoO84gkGkvWBE0j6 t32Dsd4eZrxthi9J3pmx8oPhf4mRr3+3OaYgLKLE= From: Greg Kroah-Hartman To: Johan Hovold Cc: 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: <20201202113942.27024-1-johan@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 02, 2020 at 12:39:35PM +0100, Johan Hovold wrote: > This series adds a new NORDY port flag to suppress raising the > modem-control lines on open to signal DTE readiness. > > This can be used to implement a NORDY termios control flag to complement > HUPCL, which controls lowering of the modem-control lines on final > close. > > Initially drivers can export the flag through sysfs, which also allows > control over the lines on first open. Such an interface is implemented > for serial core and USB serial. > > The motivation for this is to allow for applications where the DTR and > RTS lines are used for non-standard purposes (e.g. generating power-on > and reset pulses) to open the port without undesirable side effects. > > The final patches enables this flag by default for such a USB serial > device. > > Other examples include HAM-radio devices where DTR and RTS is used for > push-to-talk and continuous-wave control and various Arduino boards > which are reset on open unless a jumper is physically removed. > > Greg, are you ok we me taking this through my tree? I'm planning on some > follow ups to the ftdi driver and the tty/serial changes are fairly > self-contained. > > Also let me know if you prefer to hold this off for 5.12. The change is > minimal, self-contained and low-risk, but it is a new interface and late > in the release cycle as Andy pointed out. I took the first 2 patches now, that was easy :) 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). So I want to get a bunch of people to agree that this is ok to do things this way now before taking this new user-visible api. thanks, greg k-h