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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 C4BC4C11F66 for ; Tue, 29 Jun 2021 10:56:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA12F61DC2 for ; Tue, 29 Jun 2021 10:56:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233356AbhF2K7V (ORCPT ); Tue, 29 Jun 2021 06:59:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233346AbhF2K7U (ORCPT ); Tue, 29 Jun 2021 06:59:20 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DABB2C061574 for ; Tue, 29 Jun 2021 03:56:52 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id j24so2841142pfi.12 for ; Tue, 29 Jun 2021 03:56:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Jc3NxCk+KDZnIQDnHNRavHi5mkTsU8gdZSOVUuYmb/Q=; b=QS9szzKZkwbuUl6cKd5ztj/xB9uMz9A1jTb+bhp/iKdt6UXXCDtfbkgpYSl9Ld+viw 6wm5vnieXa0uuthxGAsd2dKH5l1eiA5nEb/Q01RIm+4sRZOun/GGl0IoKejxx6PU/Cxi KwW+NE7q5y9MFmWzZwJ/lOLR6FezFPiwFKp36Ggo57oNbkpfTdkz/yl0ZVaty0BvAd0Q tkint4nL99vAdnuiwBtQONS1EyfJelM8ZYkTwrROgl/HDIykl+FUEmL3aXcw5DRa/mvE VkMMefHA41nC0ZWHpWASXk0mnM1R+U1S1zX3LjB0QOklwhgqe/MbW7AabHCf9G6KZz9/ kW2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Jc3NxCk+KDZnIQDnHNRavHi5mkTsU8gdZSOVUuYmb/Q=; b=kZeu+VESdLOuRXuIJbkiuXNjDPUSXOEOOw0iZz2Qn6J82sRLgbyw87zcNxBgnzRvS7 Ci7IaRZq9V4idUVjjkKOiiEmH0oS5H4pLMd4qs6nRAWpDDMZ/ZmBDVtFCg1RAbfy6SIG X6ILmzLic/5JjmW9mG6dOcatsX1vdwzX1FEbFxZ69wgWl5fEP0whiR2A+7JgupeyOOGq G3DH/3qgk9vahxwoMYHPD88cAT6zuxux2i24yYMz4hkkZrP+vBNeuIMXpyvHA4AjP8yY PCdVG/RECjB7ZkD0p1Z3Gs1rtvqDb+rwMgesmggtGahB2CnX3krNLpSCofW9PtQg1RMG WOlQ== X-Gm-Message-State: AOAM530/dUv4KcBiVMBRSj6EImWkC9auxHTFrpQoPUeY5eZ03mrzpE9g 7f/gfITriIBWze4CEpOzbZIpHg== X-Google-Smtp-Source: ABdhPJztQOYmtid8VFswfwsuX0Ti0CJClj3s+tJOjyJNAmsG+72+n65kqxZFjJN+ujUm53A0wuaxzw== X-Received: by 2002:a63:5616:: with SMTP id k22mr27766655pgb.41.1624964212463; Tue, 29 Jun 2021 03:56:52 -0700 (PDT) Received: from localhost ([136.185.134.182]) by smtp.gmail.com with ESMTPSA id w123sm17955912pff.186.2021.06.29.03.56.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Jun 2021 03:56:51 -0700 (PDT) Date: Tue, 29 Jun 2021 16:26:49 +0530 From: Viresh Kumar To: Wolfram Sang , Jie Deng , linux-i2c@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, andriy.shevchenko@linux.intel.com, conghui.chen@intel.com, arnd@arndb.de, kblaiech@mellanox.com, jarkko.nikula@linux.intel.com, Sergey.Semin@baikalelectronics.ru, rppt@kernel.org, loic.poulain@linaro.org, tali.perry1@gmail.com, u.kleine-koenig@pengutronix.de, bjorn.andersson@linaro.org, yu1.wang@intel.com, shuo.a.liu@intel.com, stefanha@redhat.com, pbonzini@redhat.com Subject: Re: [PATCH v10] i2c: virtio: add a virtio i2c frontend driver Message-ID: <20210629105649.nt63mxtiy6u7de3g@vireshk-i7> References: <226a8d5663b7bb6f5d06ede7701eedb18d1bafa1.1616493817.git.jie.deng@intel.com> <20210629101627.kwc2rszborc3kvjs@vireshk-i7> <20210629103014.nlk3mpetydc4mi6l@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716-391-311a52 Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 29-06-21, 12:43, Wolfram Sang wrote: > > > From the spec: > > > > The case when ``length of \field{write_buf}''=0, and at the same time, > > ``length of \field{read_buf}''=0 doesn't make any sense. > > > > I mentioned this in my first reply and to my understanding I did not get > > a reply that this has changed meanwhile. > > > > Also, this code as mentioned before: > > > + if (!msgs[i].len) > > + break; > > I hope this can extended in the future to allow zero-length messages. If > this is impossible we need to set an adapter quirk instead. Ahh, yeah I saw these messages but I wasn't able to relate them to the I2C_FUNC_SMBUS_QUICK thing. My bad. Looked at Spec, Linux driver and my backends, I don't there is anything that breaks if we allow this. So the best thing (looking ahead) is if Jie sends a patch for spec to be modified like this. The case when ``length of \field{write_buf}''=0, and at the same time, ``length of \field{read_buf}''=0 is called not-a-read-write request and result for such a request is I2C device specific. -- viresh