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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A552EC6FA8B for ; Tue, 20 Sep 2022 12:10:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229822AbiITMKk (ORCPT ); Tue, 20 Sep 2022 08:10:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230020AbiITMKi (ORCPT ); Tue, 20 Sep 2022 08:10:38 -0400 Received: from bmailout3.hostsharing.net (bmailout3.hostsharing.net [IPv6:2a01:4f8:150:2161:1:b009:f23e:0]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 506A527CFD for ; Tue, 20 Sep 2022 05:10:35 -0700 (PDT) Received: from h08.hostsharing.net (h08.hostsharing.net [IPv6:2a01:37:1000::53df:5f1c:0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "*.hostsharing.net", Issuer "RapidSSL TLS DV RSA Mixed SHA256 2020 CA-1" (verified OK)) by bmailout3.hostsharing.net (Postfix) with ESMTPS id 9295F100DE9D0; Tue, 20 Sep 2022 14:10:33 +0200 (CEST) Received: by h08.hostsharing.net (Postfix, from userid 100393) id 6CE8B1B54E; Tue, 20 Sep 2022 14:10:33 +0200 (CEST) Date: Tue, 20 Sep 2022 14:10:33 +0200 From: Lukas Wunner To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= Cc: linux-serial , Greg KH , Jiri Slaby , Andy Shevchenko , Vicente Bergas , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Johan Hovold , heiko@sntech.de, giulio.benetti@micronovasrl.com, Heikki Krogerus , Raymond Tan Subject: Re: [PATCH v4 04/13] serial: 8250_dwlib: RS485 HW half & full duplex support Message-ID: <20220920121033.GA12065@wunner.de> References: <20220425143410.12703-1-ilpo.jarvinen@linux.intel.com> <20220425143410.12703-5-ilpo.jarvinen@linux.intel.com> <20220920113704.GA12014@wunner.de> <64fb5487-76c6-f6ed-d110-c98bde2f7917@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <64fb5487-76c6-f6ed-d110-c98bde2f7917@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Tue, Sep 20, 2022 at 03:01:52PM +0300, Ilpo Järvinen wrote: > I don't think you can just move from one to another like that because DE > and RTS are not the same signal on these UARTs. So it's not going to be > compatible w/o additional effort anyway. > > Initially, I tried to add a flag for selecting between the HW one and > emulation but got overruled (you were among the opposing people ;-)). > ...IIRC, I tried to explain back then that those signals are not the > same with this HW. Right, I remember that discussion. :) I guess we can always retrofit that selection option if anyone needs it. Generally if hardware RS485 support is available, one doesn't want to use software emulation. stm32-usart.c originally only had hardware-driven Driver Enable and software emulation was added afterwards because the RTS pin is sometimes pinmuxed to some other function. But such use cases are probably rare. Thanks, Lukas