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,URIBL_BLOCKED autolearn=unavailable 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 65F8FC43444 for ; Mon, 17 Dec 2018 15:43:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3EF872133F for ; Mon, 17 Dec 2018 15:43:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387560AbeLQPnN (ORCPT ); Mon, 17 Dec 2018 10:43:13 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:56636 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727564AbeLQPnN (ORCPT ); Mon, 17 Dec 2018 10:43:13 -0500 Received: from frontend01.mail.m-online.net (unknown [192.168.8.182]) by mail-out.m-online.net (Postfix) with ESMTP id 43JQR0671kz1r02K; Mon, 17 Dec 2018 16:43:08 +0100 (CET) Received: from localhost (dynscan1.mnet-online.de [192.168.6.70]) by mail.m-online.net (Postfix) with ESMTP id 43JQR046XTz1qvRX; Mon, 17 Dec 2018 16:43:08 +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 69dz0lGJFhtE; Mon, 17 Dec 2018 16:43:07 +0100 (CET) X-Auth-Info: uCA/xwTQNCN29wazrd7eps4Mp/jltM6c4caImNMwyI4= 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; Mon, 17 Dec 2018 16:43:07 +0100 (CET) Subject: Re: [PATCH] Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again" To: Greg Kroah-Hartman , Paul Burton Cc: Ezequiel Garcia , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Paul Burton , Daniel Jedrychowski , "linux-mips@vger.kernel.org" , stable , Ezequiel Garcia References: <20181213174834.kxdy6fphaeoivqgh@pburton-laptop> <20181216200833.27928-1-paul.burton@mips.com> <20181216213133.kwe24pif3v4wcgwp@pburton-laptop> <949fdd3d-535e-d235-f406-d5bde4658c5e@denx.de> <20181216222411.5jkexuaqxpfudj7b@pburton-laptop> <20181216223510.hxsdotf332ousinh@pburton-laptop> <20181217151851.GA21564@kroah.com> From: Marek Vasut Message-ID: <52a4b322-5710-1ac0-fa3e-11ed6ef2236d@denx.de> Date: Mon, 17 Dec 2018 16:43:06 +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: <20181217151851.GA21564@kroah.com> 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 12/17/2018 04:18 PM, Greg Kroah-Hartman wrote: > On Sun, Dec 16, 2018 at 10:35:12PM +0000, Paul Burton wrote: >> Hi Ezequiel, >> >> On Sun, Dec 16, 2018 at 07:28:22PM -0300, Ezequiel Garcia wrote: >>> On Sun, 16 Dec 2018 at 19:24, Paul Burton wrote: >>>> This helps, but it only addresses one part of one of the 4 reasons I >>>> listed as motivation for my revert. For example serial8250_do_shutdown() >>>> also clearly intends to disable the FIFOs. >>>> >>> >>> OK. So, let's fix that :-) >> >> I already did, or at least tried to, on Thursday [1]. >> >>> By all means, it would be really nice to push forward and fix the garbage >>> issue on JZ4780, as well as the transmission issue on AM335x. >>> >>> AM335x is a wildly popular platform, and it's not funny to break it. >> >> Well, clearly not if it was broken in v4.10 & only just fixed..? And >> from Marek's commit message the patch in v4.10 doesn't break the whole >> system just RS485. >> >>> So, let's please stop discussing which board we'll break and just fix both. >> >> I completely agree that would be ideal and I wrote a patch hoping to do >> that on Thursday, but didn't get any response on testing. It's late in >> the cycle hence a revert made sense. Simple as that. > > A revert makes sense now, I'll go queue this up, thanks. I don't like this for multiple reasons. 1) There is a better patch posted which doesn't break the AM335x and clearly identifies and fixes the problem on the JZ4780 / CI20 2) The JZ4780 8250 core is not a standard 8250 core, since it has extra bits in the FCR register (like the UME bit, which disables the whole UART block), so the revert IMO would break that core too, it just hides the breakage. I'm still trying to understand the implications of that in detail, but the discussion wasn't quite constructive. I'd much rather see Ezequiel's patch applied, since that's far less destructive approach to fixing the problem than the revert. -- Best regards, Marek Vasut