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=-8.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 407D0C433E2 for ; Thu, 17 Sep 2020 15:05:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8759206D4 for ; Thu, 17 Sep 2020 15:05:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="J9O1vvrV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727922AbgIQPFe (ORCPT ); Thu, 17 Sep 2020 11:05:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726980AbgIQPD2 (ORCPT ); Thu, 17 Sep 2020 11:03:28 -0400 Received: from mail-lf1-x144.google.com (mail-lf1-x144.google.com [IPv6:2a00:1450:4864:20::144]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 27AB0C06174A; Thu, 17 Sep 2020 08:03:08 -0700 (PDT) Received: by mail-lf1-x144.google.com with SMTP id w11so2557179lfn.2; Thu, 17 Sep 2020 08:03:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=2to3njOhdgwuq2I1e40+Byq+xuhBorXNqPr31tThoUc=; b=J9O1vvrVbuKnfKsqZIgRgTDLgrPDmqrKWY+i7RAW6XcFsqSBX0b2+XLOWXun5fMkTA 04H/gk6m1F+bLw3GztpOgaDKJhC7orQ971r+DD2MIWiBZ+5B3y/Vv7470b5QV/6BR0Ah khpzgNubtj12Bv5iVi5TqwMPfJVYUpi+HtpG5mREM+JA2CRziqCjzvIE8H0NaHHLyDeM UJoKvhtZ2IxV4NLnl28VnyXsZscVAPx4aoC3XSznGtnkg0k/nx1aYYKirLdkG1wkir9f Otvd7Q83VSis0Jyye0720IYiLqbznCIxAsz/G25Ky2LwBTyXK1ptIF//S6NG7YEIekE3 KCaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=2to3njOhdgwuq2I1e40+Byq+xuhBorXNqPr31tThoUc=; b=W+u/J6VunLIH4w8pYWvrpg4eIzynrO6anXm6jrQHtJMM1oj+QRQJ8GWRgSYSL+Vl2o iLOF1eOS0qw2bQVKzMDJiYhqU/KfcpZC5qqysZ/cGaVj8WOmSn2Bo0YV7eG86DcwzrYd j6BmTrWMUaDZHlgq4YLD66e0DSez7fGzVnW1SPdIXxcl60cOD6qTP/6tgM3H4rJmIHcx XmJUACqwPodlYfgUaUlvsBqn2RAaCmuY+eJUmBYpgV8luBBj+kQdvcrZr+Ns7rsuXumR NLkKY2+YrgBHX2gtQ6EGOi/LRFajsLbDtSTcQkZxYXM7+EeKiMlQNPTBf6tTRPfeTbVL 2gRQ== X-Gm-Message-State: AOAM533GmIlnBRc4H+53WsChePA7rhvMa0V298aEJq+WYDlqRijj28mv 34kVOSvwzjqOK6Sb7y8LhEaaDXmxBxM= X-Google-Smtp-Source: ABdhPJydlsr2iB7rq7ppcGxNzHIn7O29QeEihjdv8v2bssXmptvp8ORFcdItk4FAToY1McQWvXvmog== X-Received: by 2002:a19:606:: with SMTP id 6mr8640701lfg.407.1600354986387; Thu, 17 Sep 2020 08:03:06 -0700 (PDT) Received: from [192.168.2.145] (109-252-170-211.dynamic.spd-mgts.ru. [109.252.170.211]) by smtp.googlemail.com with ESMTPSA id b27sm5313220lfq.133.2020.09.17.08.03.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Sep 2020 08:03:05 -0700 (PDT) Subject: Re: [PATCH v7 21/34] i2c: tegra: Don't fall back to PIO mode if DMA configuration fails To: Thierry Reding Cc: Jonathan Hunter , Laxman Dewangan , Wolfram Sang , =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= , Andy Shevchenko , linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200908224006.25636-1-digetx@gmail.com> <20200908224006.25636-22-digetx@gmail.com> <20200917114716.GZ3515672@ulmo> From: Dmitry Osipenko Message-ID: Date: Thu, 17 Sep 2020 18:03:04 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200917114716.GZ3515672@ulmo> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 17.09.2020 14:47, Thierry Reding пишет: > On Wed, Sep 09, 2020 at 01:39:53AM +0300, Dmitry Osipenko wrote: >> The DMA code path has been tested well enough and the DMA configuration >> performed by tegra_i2c_config_fifo_trig() shouldn't ever fail in practice. >> Hence let's remove the obscure transfer-mode switching in order to have a >> cleaner and simpler code. Now I2C transfer will be failed if DMA >> configuration fails. >> >> Signed-off-by: Dmitry Osipenko >> --- >> drivers/i2c/busses/i2c-tegra.c | 18 ++++++++++-------- >> 1 file changed, 10 insertions(+), 8 deletions(-) > > I'm not sure that's a good idea. It's always possible that the DMA setup > is going to break because of something that's not related to the I2C > driver itself. Having the system completely break instead of falling > back to PIO mode seems like it would only complicate troubleshooting any > such issues. That code has zero test coverage because this problem never happens in practice, hence it should be better to have it removed. We may consider re-adding it back if there will be a real-world incident, okay?