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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 3BE26C433E9 for ; Fri, 12 Mar 2021 07:52:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED0D864F83 for ; Fri, 12 Mar 2021 07:52:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231659AbhCLHv3 (ORCPT ); Fri, 12 Mar 2021 02:51:29 -0500 Received: from mga07.intel.com ([134.134.136.100]:30252 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231551AbhCLHvT (ORCPT ); Fri, 12 Mar 2021 02:51:19 -0500 IronPort-SDR: RJ+gevUbVBQQi2NuBlk7pahUqeCwd4vs5v9KLZAUVAmuf0ZTvNaBjWBpRQNiaGQ3vjwbg0o6Ll Nse8T/wtD2fQ== X-IronPort-AV: E=McAfee;i="6000,8403,9920"; a="252816244" X-IronPort-AV: E=Sophos;i="5.81,242,1610438400"; d="scan'208";a="252816244" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Mar 2021 23:51:18 -0800 IronPort-SDR: QgIHLYUoIhc3VMN/Gf7KW8hgMzXD4k1qeOW56J2W/90ORAv0QR5iBzoGT0zfO082kgxu+Y3aR1 uR/ssjQm7IiA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,242,1610438400"; d="scan'208";a="377633179" Received: from unknown (HELO [10.239.154.55]) ([10.239.154.55]) by fmsmga007.fm.intel.com with ESMTP; 11 Mar 2021 23:51:13 -0800 Subject: Re: [PATCH v7] i2c: virtio: add a virtio i2c frontend driver To: Viresh Kumar Cc: linux-i2c@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, mst@redhat.com, wsa@kernel.org, jasowang@redhat.com, wsa+renesas@sang-engineering.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 References: <20210312061012.slmfnhxe6y5kgrnv@vireshk-i7> From: Jie Deng Message-ID: Date: Fri, 12 Mar 2021 15:51:13 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210312061012.slmfnhxe6y5kgrnv@vireshk-i7> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 2021/3/12 14:10, Viresh Kumar wrote: > I saw your email about wrong version being sent, I already wrote some > reviews. Sending them anyway for FWIW :) > > On 12-03-21, 21:33, Jie Deng wrote: >> +struct virtio_i2c { >> + struct virtio_device *vdev; >> + struct completion completion; >> + struct i2c_adapter adap; >> + struct mutex lock; > As I said in the previous version (Yes, we were both waiting for > Wolfram to answer that), this lock shouldn't be required at all. > > And since none of us have a use-case at hand where we will have a > problem without this lock, we should really skip it. We can always > come back and add it if we find an issue somewhere. Until then, better > to keep it simple. The problem is you can't guarantee that adap->algo->master_xfer is only called from i2c_transfer. Any function who holds the adapter can call adap->algo->master_xfer directly. I prefer to avoid potential issues rather than find a issue then fix. > >> + >> +static struct i2c_adapter virtio_adapter = { >> + .owner = THIS_MODULE, >> + .name = "Virtio I2C Adapter", >> + .class = I2C_CLASS_DEPRECATED, > What happened to this discussion ? > > https://lore.kernel.org/lkml/20210305072903.wtw645rukmqr5hx5@vireshk-i7/ My understanding is that new driver sets this to warn users that the adapter doesn't support classes anymore. I'm not sure if Wolfram can explain it more clear for you. > >> + .algo = &virtio_algorithm, >> + >> + return ret; >> + >> + vi->adap = virtio_adapter; > This is strange, why are you allocating memory for adapter twice ? > Once for virtio_adapter and once for vi->adap ? Either fill the fields > directly for v->adap here and remove virtio_adapter or make vi->adap a > pointer. Will make vi->adap a pointer. Thanks.