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=-8.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 66FB7C433E2 for ; Fri, 4 Sep 2020 03:39:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 345FD206EF for ; Fri, 4 Sep 2020 03:39:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="V67Xi82e" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729582AbgIDDjI (ORCPT ); Thu, 3 Sep 2020 23:39:08 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:45823 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729554AbgIDDjG (ORCPT ); Thu, 3 Sep 2020 23:39:06 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1599190744; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=EyAiC4eZwNkau3Y8SAq/5Z+4k7VTrQOqY9EtVuiJLAo=; b=V67Xi82e9Qwve0TwFj6v1onSQLStwniYDG+qUpcI3SVo9FIXUHyawSYEQfKVhJ+Cqg2s9h l3uKV7VQS78kMmG+iML/GVH/urpSQ6Qqx4QOs9Ju/KMw3Fv70VFKKxfjV37cGeV1Wwc60X BX1VoFmG6UIc2+li/Nf+dtS1N4v0xzU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-448-O7FrjF36NT6sUEUv99XNOw-1; Thu, 03 Sep 2020 23:39:00 -0400 X-MC-Unique: O7FrjF36NT6sUEUv99XNOw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A117B807344; Fri, 4 Sep 2020 03:38:57 +0000 (UTC) Received: from [10.72.13.157] (ovpn-13-157.pek2.redhat.com [10.72.13.157]) by smtp.corp.redhat.com (Postfix) with ESMTP id 14FFC7EEBB; Fri, 4 Sep 2020 03:38:46 +0000 (UTC) Subject: Re: [PATCH] i2c: virtio: add a virtio i2c frontend driver To: Jie Deng , linux-i2c@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Cc: mst@redhat.com, wsa+renesas@sang-engineering.com, wsa@kernel.org, andriy.shevchenko@linux.intel.com, jarkko.nikula@linux.intel.com, jdelvare@suse.de, Sergey.Semin@baikalelectronics.ru, krzk@kernel.org, rppt@kernel.org, loic.poulain@linaro.org, tali.perry1@gmail.com, bjorn.andersson@linaro.org, shuo.a.liu@intel.com, conghui.chen@intel.com, yu1.wang@intel.com References: <0efc2605c8c06b4b1bf68cbad5536c4a900dc019.1599110284.git.jie.deng@intel.com> <6517879c-15d4-6265-761c-626cba9c95d6@intel.com> From: Jason Wang Message-ID: <009d829d-907d-8884-ca71-00f78e9d6e2b@redhat.com> Date: Fri, 4 Sep 2020 11:38:45 +0800 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: <6517879c-15d4-6265-761c-626cba9c95d6@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On 2020/9/3 下午3:19, Jie Deng wrote: > > On 2020/9/3 14:12, Jason Wang wrote: >> >> On 2020/9/3 下午1:34, Jie Deng wrote: >>> Add an I2C bus driver for virtio para-virtualization. >>> >>> The controller can be emulated by the backend driver in >>> any device model software by following the virtio protocol. >>> >>> This driver communicates with the backend driver through a >>> virtio I2C message structure which includes following parts: >>> >>> - Header: i2c_msg addr, flags, len. >>> - Data buffer: the pointer to the i2c msg data. >>> - Status: the processing result from the backend. >>> >>> People may implement different backend drivers to emulate >>> different controllers according to their needs. A backend >>> example can be found in the device model of the open source >>> project ACRN. For more information, please refer to >>> https://projectacrn.org. >> >> >> May I know the reason why don't you use i2c or virtio directly? >> > We don't want to add virtio drivers for every I2C devices in the guests. > This bus driver is designed to provide a way to flexibly expose the > physical > I2C slave devices to the guest without adding or changing the drivers > of the > I2C slave devices in the guest OS. Ok, if I understand this correctly, this is virtio transport of i2c message (similar to virtio-scsi). > > >> >>> >>> The virtio device ID 34 is used for this I2C adpter since IDs >>> before 34 have been reserved by other virtio devices. >> >> >> Is there a link to the spec patch? >> >> Thanks >> > I haven't submitted the patch to reserve the ID in spec yet. > I write the ID here because I want to see your opinions first. It would be helpful to send a spec draft for early review. Thanks > > Thanks > >