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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 76389C433EF for ; Sat, 25 Jun 2022 09:55:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:Message-ID: In-Reply-To:Subject:cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zgfoXISkibS9zcFaRIMDDjWi4M9ANKad/dZiWy9QJp4=; b=zPHQPTWUOvbqG4 n5rKdp6LJiC6oR8XVdgIZzAn2RITdpHSLEND5Odjy4VCWMp8ByQCDBHgp4q8xXPyGnpWjMvz3mljQ rMbuRvZDdx7dTWbYE8YaRThx0EECRH1wa7kBFhgJl3WBNn8b953YUE/KqhJkCrBtN4F49uizyQNqI zJWyDkNcFWhzfUcRmH0P4mIucJIiKq7cX8RVgsy+iXAWnYJ1QxRE13UphcRcoOJQSJwSK5O8SAtgY ZHD5Mp+peKGZpFF3iTj7Y0wU9+Yu0SRuZPl57XFbddy3BkIowsxJYsq/B/8/sv6587kakOThSnm28 +0sMFkOLWSBXeiK3Nzdw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o52V9-005Pzj-KW; Sat, 25 Jun 2022 09:54:51 +0000 Received: from mga07.intel.com ([134.134.136.100]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o52V6-005Pwt-LV for linux-arm-kernel@lists.infradead.org; Sat, 25 Jun 2022 09:54:50 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1656150888; x=1687686888; h=date:from:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=VKuQVwQN3wupa/wWGwfy2HpIYFCAp6PhOr5/aA9piQw=; b=kl810WVx+F8hVU6fc3oN3kMuiL02rFQRjXvUTcmo7Nw65TbSLhGw9Tgf 56t7B4nlettzO13hOKp99ek/mXXgmVCv7khXuUg9WBfEp0UCpQEAyikhP ZJH4rFxTVD2Wrcp/M1WpeKQK8wF3v3wdKzDxXUXJe02scVrdsftS0Ncei 6HzLMqzAue3JsyCZdIPmzWy9cLEbNbiV5p96i33kgSIOF0qydOaPGwrhF VBJEaqJJsprYbkOKXKDeh3tckwbZFFWKX+9vus+wPWJaRuy9mRUWO7xdR jqQYtWx/j45xt9rtQmOulGvvbNifbfj5tP/iZ799DnoiJN3RfBCAzj1Hq A==; X-IronPort-AV: E=McAfee;i="6400,9594,10388"; a="345173872" X-IronPort-AV: E=Sophos;i="5.92,222,1650956400"; d="scan'208";a="345173872" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2022 02:54:45 -0700 X-IronPort-AV: E=Sophos;i="5.92,222,1650956400"; d="scan'208";a="645644075" Received: from selvaku-mobl.ger.corp.intel.com ([10.252.60.244]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jun 2022 02:54:42 -0700 Date: Sat, 25 Jun 2022 12:54:39 +0300 (EEST) From: =?ISO-8859-15?Q?Ilpo_J=E4rvinen?= To: Lino Sanfilippo cc: Andy Shevchenko , Greg Kroah-Hartman , Jiri Slaby , robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, vz@mleia.com, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-serial , LKML , lukas@wunner.de, p.rosenberger@kunbus.com, Lino Sanfilippo Subject: Re: [PATCH 5/8] dt_bindings: rs485: Correct delay values In-Reply-To: <6c50fdca-aac4-aaf5-ad34-18a60fcc0aa0@gmx.de> Message-ID: References: <20220622154659.8710-1-LinoSanfilippo@gmx.de> <20220622154659.8710-6-LinoSanfilippo@gmx.de> <6c50fdca-aac4-aaf5-ad34-18a60fcc0aa0@gmx.de> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220625_025448_803154_3CF0E7BD X-CRM114-Status: GOOD ( 20.90 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, 23 Jun 2022, Lino Sanfilippo wrote: > On 23.06.22 at 18:29, Andy Shevchenko wrote: > > On Wed, Jun 22, 2022 at 05:46:56PM +0200, Lino Sanfilippo wrote: > >> From: Lino Sanfilippo > >> > >> The maximum allowed delay for RTS before and RTS after send is 100 ms. > >> Adjust the documentation accordingly. > > > > > > Is it only documentation issue? If the code allows this to be set higher > > than 100, we may not change the documentation since this an ABI (from > > firmware <--> kernel perspective) we need to support old variants. > > > > Well currently the documentation claims that a maximum of 1000 msecs is allowed but > nothing actually checks the values read from device tree/ACPI and so it is possible > to set much higher values (note that the UART drivers dont check the delays read from > DT/ACPI either, the only exception I found is max310x which clamps it to 15 ms). > > We already have a maximum of 100 ms defined for RTS delays set via TIOCSRS485. To be > consistent with TIOCSRS485 the same limit is used for DT/ACPI values in this patch. > > I am aware that this changes the firmware/kernel ABI. But we had a similar situation when > the sanity checks for TIOCSRS485 were introduced > (see https://lore.kernel.org/all/20220410104642.32195-2-LinoSanfilippo@gmx.de/) > since before we did not have those limits for all drivers (some drivers clamped the > values itself but many did not care). > Furthermore 100 ms is already a very high value for RTS delays (which are usually rather > in usecs range). So IMHO the risk is very low to break anything when values are clamped > that are higher than that. Did you see this development direction (from Lukas): https://lore.kernel.org/linux-serial/20220309125908.GA9283@wunner.de/ ? Effectively, he wants to making a compat threshold at 1msec and beyond that the input value would be interpreted as nsecs. -- i. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel