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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 559B1C43387 for ; Sun, 16 Dec 2018 22:01:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E4DB2084A for ; Sun, 16 Dec 2018 22:01:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730970AbeLPWB1 (ORCPT ); Sun, 16 Dec 2018 17:01:27 -0500 Received: from mail-out.m-online.net ([212.18.0.10]:38436 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730860AbeLPWB1 (ORCPT ); Sun, 16 Dec 2018 17:01:27 -0500 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 43Hysw06Nhz1r0Gm; Sun, 16 Dec 2018 23:01:24 +0100 (CET) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 43Hysv6bn9z1qsZC; Sun, 16 Dec 2018 23:01:23 +0100 (CET) X-Virus-Scanned: amavisd-new at mnet-online.de Received: from mail.mnet-online.de ([192.168.8.182]) by localhost (dynscan1.mail.m-online.net [192.168.6.70]) (amavisd-new, port 10024) with ESMTP id CFL1_clki3N4; Sun, 16 Dec 2018 23:01:22 +0100 (CET) X-Auth-Info: 7/tF+Q5YzpxPXbvQsValM1HSKK9qBtjYYVo4W7puvpw= Received: from [IPv6:::1] (unknown [195.140.253.167]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.mnet-online.de (Postfix) with ESMTPSA; Sun, 16 Dec 2018 23:01:22 +0100 (CET) Subject: Re: [PATCH] Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again" To: Paul Burton Cc: "linux-serial@vger.kernel.org" , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" , Paul Burton , Daniel Jedrychowski , "linux-mips@vger.kernel.org" , stable References: <20181213174834.kxdy6fphaeoivqgh@pburton-laptop> <20181216200833.27928-1-paul.burton@mips.com> <93a3c76b-f4ba-57ae-9d80-6e945b4f3181@denx.de> <20181216213901.hpll7wqzhqvfgkfy@pburton-laptop> From: Marek Vasut Message-ID: <28a1d4ae-493d-8bbc-46f7-ad41ca04d782@denx.de> Date: Sun, 16 Dec 2018 23:01:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20181216213901.hpll7wqzhqvfgkfy@pburton-laptop> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 12/16/2018 10:39 PM, Paul Burton wrote: > Hi Marek, Hi, > On Sun, Dec 16, 2018 at 10:08:48PM +0100, Marek Vasut wrote: >>> I did suggest an alternative approach which would rename >>> serial8250_clear_fifos() and split it into 2 variants - one that >>> disables FIFOs & one that does not, then use the latter in >>> __do_stop_tx_rs485(): >>> >>> https://lore.kernel.org/lkml/20181213014805.77u5dzydo23cm6fq@pburton-laptop/ >>> >>> However I have no access to the OMAP3 hardware that Marek's patch was >>> attempting to fix & have heard nothing back with regards to him testing >>> that approach, so here's a simple revert that fixes the Ingenic JZ4780. >>> >>> I've marked for stable back to v4.10 presuming that this is how far the >>> broken patch may be backported, given that this is where commit >>> 2bed8a8e7072 ("Clearing FIFOs in RS485 emulation mode causes subsequent >>> transmits to break") that it tried to fix was introduced. >> >> OK, I tested this on AM335x / OMAP3 and the system is again broken, so >> that's a NAK. > > To be clear - what did you test? This revert or the patch linked to > above? > > This revert would of course reintroduce your RS485 issue because it just > undoes your change. The revert. Which of the two patches do you need me to test. > Either way, commit f6aa5beb45be ("serial: 8250: Fix clearing FIFOs in > RS485 mode again") breaks systems that worked before it so at this late > stage in the 4.20 cycle a revert would make sense to me. If that breaks > RS85 on OMAP3 then my question would be how much can anyone really care > if nobody noticed since v4.10? And why should that lead to you breaking > the JZ4780 which has been discovered before a stable kernel release > includes the breakage? There's always a .y release where this can be properly investigated and solved, instead of breaking one platform or the other. Then again, see the patch from Ezequiel that was just posted, I think it might be a far better solution. -- Best regards, Marek Vasut