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=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 F34EEC433ED for ; Wed, 7 Apr 2021 14:28:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D61D661260 for ; Wed, 7 Apr 2021 14:28:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352898AbhDGO2p (ORCPT ); Wed, 7 Apr 2021 10:28:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229449AbhDGO2m (ORCPT ); Wed, 7 Apr 2021 10:28:42 -0400 Received: from mail-ot1-x32d.google.com (mail-ot1-x32d.google.com [IPv6:2607:f8b0:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FCBEC061756; Wed, 7 Apr 2021 07:28:32 -0700 (PDT) Received: by mail-ot1-x32d.google.com with SMTP id g8-20020a9d6c480000b02901b65ca2432cso18245169otq.3; Wed, 07 Apr 2021 07:28:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:reply-to:references :mime-version:content-disposition:in-reply-to; bh=jOETYTM8063hIe+H5kFUr3hMwnez+idh/fGpidnkrFU=; b=LareH35xQvx6q7WindtheaqOLJg6+SkWSAntFgw7HjS3Tk4qDPoemJ1YOk85nmgPvg 9mZw56tpm53uQl29e+NuknOwYdP0xUGUxUvEzj64/Y7PD4nxPHMwswMAL8E4iHbcAhMx h0MdSnsyeyH4HD8RzChFdMtN/SVH7ahCvfGaZEIguKsC0HUgs97KIN7GkKUfnrLM2q+p MiRkxAMy9OTppt3tkoTAy1Zc4dPeODYOUi9GXRMbSxlEeRbbwdMytDy+G8hVjD1aj6yC LVzR9U89e8uevanQxmVqNCGOgMvZJvLBAuD6ahPOCf7aN31WHqeQdfIWyETLDQl2tc04 +zlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :reply-to:references:mime-version:content-disposition:in-reply-to; bh=jOETYTM8063hIe+H5kFUr3hMwnez+idh/fGpidnkrFU=; b=O+sUwYEZLXGk49XvVpKky91ioIhwz2qmw7xSIcuyDmrianZedtloujq91tX7IKOabl I54ipugZrY5xl1HCaTUFz6c9MHo42qOyvOoey3+O6unZoiVv5S0/CsxHj3u2DMwGHsdf 5gNF3l4N6B+qj+rKgW7uAmY8b7lAThGr6jrWD1Vpc4JCKzNri+Wh9pThJ2wf7sO9b6Dq Wtq6mmUn6Hf292eK8Gny9XNgLfUZG14Sbot0jQ3+I79Ufkbgvc0B2WmkpRbiVOlTQtRq SPfNcNZv3qMFwY4MPHLfe5bK+aXzmZRS/gOwL7FwCLH7b+JqFSp0EvdBDXuzKZ4yUPRY hlng== X-Gm-Message-State: AOAM532sewWqvpfSCiC4FZuswdJc4+55524+tS5YatmwCyXtKg8OmaFo mwZE6em8CGWGgphSSNNw+1GSd70SfsCr X-Google-Smtp-Source: ABdhPJxYDEUlP0EObBbm9VfamGrvC+u2TKkp/NeoRSzuuBtqMWkEEaA6ECIMT4B8dpnH6MIjEYoYqQ== X-Received: by 2002:a9d:37b4:: with SMTP id x49mr3212457otb.237.1617805711619; Wed, 07 Apr 2021 07:28:31 -0700 (PDT) Received: from serve.minyard.net (serve.minyard.net. [2001:470:b8f6:1b::1]) by smtp.gmail.com with ESMTPSA id h24sm5501853otg.20.2021.04.07.07.28.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Apr 2021 07:28:30 -0700 (PDT) Sender: Corey Minyard Received: from minyard.net (unknown [IPv6:2001:470:b8f6:1b:f036:ecd9:2bd0:ef09]) by serve.minyard.net (Postfix) with ESMTPSA id 89595180570; Wed, 7 Apr 2021 14:28:29 +0000 (UTC) Date: Wed, 7 Apr 2021 09:28:28 -0500 From: Corey Minyard To: Quan Nguyen Cc: Rob Herring , Joel Stanley , Andrew Jeffery , Wolfram Sang , Philipp Zabel , openipmi-developer@lists.sourceforge.net, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, Open Source Submission , Phong Vo , "Thang Q . Nguyen" Subject: Re: [PATCH v2 0/3] Add Aspeed SSIF BMC driver Message-ID: <20210407142828.GE7166@minyard.net> Reply-To: minyard@acm.org References: <20210330141029.20412-1-quan@os.amperecomputing.com> <20210402142124.GV507977@minyard.net> <0e7fceff-4a01-5cb0-72eb-8b47d598f1c3@os.amperecomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0e7fceff-4a01-5cb0-72eb-8b47d598f1c3@os.amperecomputing.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 07, 2021 at 08:09:50PM +0700, Quan Nguyen wrote: > Hi Corey, > > Thank you for reviewing > I'll put my respond inline below. > > -Quan > > On 02/04/2021 21:21, Corey Minyard wrote: > > On Tue, Mar 30, 2021 at 09:10:26PM +0700, Quan Nguyen wrote: > > > This series add support for the Aspeed specific SSIF BMC driver which > > > is to perform in-band IPMI communication with the host in management > > > (BMC) side. > > > > I don't have any specific feedback for this, but I'm wondering if it's > > really necessary. > > > > Why can't the BMC just open the I2C device and use it? Is there any > > functionality that this provides that cannot be accomplished from > > userland access to the I2C device? I don't see any. > > > > If it tied into some existing framework to give abstract access to a BMC > > slave side interface, I'd be ok with this. But I don't see that. > > > > The SSIF at the BMC side acts as an I2C slave and we think that the kernel > driver is unavoidable to handle the I2c slave events > (https://www.kernel.org/doc/html/latest/i2c/slave-interface.html) > > And to make it works with existing OpenBMC IPMI stack, a userspace part, > ssifbridge, is needed (https://github.com/openbmc/ssifbridge). This > ssifbridge is to connect this driver with the OpenBMC IPMI stack so the IPMI > stack can communicate via SSIF channel in similar way that was implemented > with BT and KCS (ie: btbridge/kcsbridge and its corespondent kernel drivers > (https://github.com/openbmc/btbridge and > https://github.com/openbmc/kcsbridge)) Dang, I don't know why there's not a generic userland interface for the slave. And I've made this mistake before :(. Anyway, you are right, you need a driver. I'll review. -corey > > > Unless there is a big need to have this in the kernel, I'm against > > including this and would suggest you do all this work in userland. > > Perhaps write a library. Sorry, but I'm trying to do my part to reduce > > unnecessary things in the kernel. > > > > Thanks, > > > > -corey > > 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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS 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 37155C433B4 for ; Wed, 7 Apr 2021 14:29:02 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 729F2611C1 for ; Wed, 7 Apr 2021 14:29:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 729F2611C1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=acm.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4FFmwq62HKz3bvX for ; Thu, 8 Apr 2021 00:28:59 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=LareH35x; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gmail.com (client-ip=2607:f8b0:4864:20::335; helo=mail-ot1-x335.google.com; envelope-from=tcminyard@gmail.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20161025 header.b=LareH35x; dkim-atps=neutral Received: from mail-ot1-x335.google.com (mail-ot1-x335.google.com [IPv6:2607:f8b0:4864:20::335]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4FFmwM5nKmz2yYn; Thu, 8 Apr 2021 00:28:34 +1000 (AEST) Received: by mail-ot1-x335.google.com with SMTP id w31-20020a9d36220000b02901f2cbfc9743so18216465otb.7; Wed, 07 Apr 2021 07:28:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:reply-to:references :mime-version:content-disposition:in-reply-to; bh=jOETYTM8063hIe+H5kFUr3hMwnez+idh/fGpidnkrFU=; b=LareH35xQvx6q7WindtheaqOLJg6+SkWSAntFgw7HjS3Tk4qDPoemJ1YOk85nmgPvg 9mZw56tpm53uQl29e+NuknOwYdP0xUGUxUvEzj64/Y7PD4nxPHMwswMAL8E4iHbcAhMx h0MdSnsyeyH4HD8RzChFdMtN/SVH7ahCvfGaZEIguKsC0HUgs97KIN7GkKUfnrLM2q+p MiRkxAMy9OTppt3tkoTAy1Zc4dPeODYOUi9GXRMbSxlEeRbbwdMytDy+G8hVjD1aj6yC LVzR9U89e8uevanQxmVqNCGOgMvZJvLBAuD6ahPOCf7aN31WHqeQdfIWyETLDQl2tc04 +zlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :reply-to:references:mime-version:content-disposition:in-reply-to; bh=jOETYTM8063hIe+H5kFUr3hMwnez+idh/fGpidnkrFU=; b=Y+W2gyXYc/tbt1bUxaK/jI4wAoymqCAkBo50W4UZpDER1aHPv++gv2GgM/LNWNiXXX /v+sdxix9A5afyds5sj7jfDXTpMyGLKyvFxcNNd1HyVvWjURtEhFZLeRySsg5X+bBuRo ruBrhZn6otfpzO66BMXCNebhYFXhBPbhA59YC0KRFI6fiVIL/UZZCQ1nuqmqt47qSpq9 9w2cs35SNzQNsuZIQfz6KSo5EO+quSghAQVE6h4Ktzfg+EZ6NerrJJBjAjKZy7+DgY+9 6uaQRuFSjOItFyx2q9lfuGuEJmlagLjbD5P1cXF2g+wvtaIpLdRyGDeCH7CbWkPQcBr3 sJCA== X-Gm-Message-State: AOAM530ICa1Mt1Gpk6aoMpmPLmxt2DzEJNf32ILxf0/U+q5m80634Oic Q3vDeIyvvapGKjBnL8azBA== X-Google-Smtp-Source: ABdhPJxYDEUlP0EObBbm9VfamGrvC+u2TKkp/NeoRSzuuBtqMWkEEaA6ECIMT4B8dpnH6MIjEYoYqQ== X-Received: by 2002:a9d:37b4:: with SMTP id x49mr3212457otb.237.1617805711619; Wed, 07 Apr 2021 07:28:31 -0700 (PDT) Received: from serve.minyard.net (serve.minyard.net. [2001:470:b8f6:1b::1]) by smtp.gmail.com with ESMTPSA id h24sm5501853otg.20.2021.04.07.07.28.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Apr 2021 07:28:30 -0700 (PDT) Received: from minyard.net (unknown [IPv6:2001:470:b8f6:1b:f036:ecd9:2bd0:ef09]) by serve.minyard.net (Postfix) with ESMTPSA id 89595180570; Wed, 7 Apr 2021 14:28:29 +0000 (UTC) Date: Wed, 7 Apr 2021 09:28:28 -0500 From: Corey Minyard To: Quan Nguyen Subject: Re: [PATCH v2 0/3] Add Aspeed SSIF BMC driver Message-ID: <20210407142828.GE7166@minyard.net> References: <20210330141029.20412-1-quan@os.amperecomputing.com> <20210402142124.GV507977@minyard.net> <0e7fceff-4a01-5cb0-72eb-8b47d598f1c3@os.amperecomputing.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0e7fceff-4a01-5cb0-72eb-8b47d598f1c3@os.amperecomputing.com> X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: minyard@acm.org Cc: devicetree@vger.kernel.org, linux-aspeed@lists.ozlabs.org, Andrew Jeffery , openbmc@lists.ozlabs.org, "Thang Q . Nguyen" , linux-kernel@vger.kernel.org, Phong Vo , Wolfram Sang , Rob Herring , Philipp Zabel , openipmi-developer@lists.sourceforge.net, Open Source Submission , linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org Errors-To: openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org Sender: "openbmc" On Wed, Apr 07, 2021 at 08:09:50PM +0700, Quan Nguyen wrote: > Hi Corey, > > Thank you for reviewing > I'll put my respond inline below. > > -Quan > > On 02/04/2021 21:21, Corey Minyard wrote: > > On Tue, Mar 30, 2021 at 09:10:26PM +0700, Quan Nguyen wrote: > > > This series add support for the Aspeed specific SSIF BMC driver which > > > is to perform in-band IPMI communication with the host in management > > > (BMC) side. > > > > I don't have any specific feedback for this, but I'm wondering if it's > > really necessary. > > > > Why can't the BMC just open the I2C device and use it? Is there any > > functionality that this provides that cannot be accomplished from > > userland access to the I2C device? I don't see any. > > > > If it tied into some existing framework to give abstract access to a BMC > > slave side interface, I'd be ok with this. But I don't see that. > > > > The SSIF at the BMC side acts as an I2C slave and we think that the kernel > driver is unavoidable to handle the I2c slave events > (https://www.kernel.org/doc/html/latest/i2c/slave-interface.html) > > And to make it works with existing OpenBMC IPMI stack, a userspace part, > ssifbridge, is needed (https://github.com/openbmc/ssifbridge). This > ssifbridge is to connect this driver with the OpenBMC IPMI stack so the IPMI > stack can communicate via SSIF channel in similar way that was implemented > with BT and KCS (ie: btbridge/kcsbridge and its corespondent kernel drivers > (https://github.com/openbmc/btbridge and > https://github.com/openbmc/kcsbridge)) Dang, I don't know why there's not a generic userland interface for the slave. And I've made this mistake before :(. Anyway, you are right, you need a driver. I'll review. -corey > > > Unless there is a big need to have this in the kernel, I'm against > > including this and would suggest you do all this work in userland. > > Perhaps write a library. Sorry, but I'm trying to do my part to reduce > > unnecessary things in the kernel. > > > > Thanks, > > > > -corey > > 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=-8.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 F3E09C433B4 for ; Wed, 7 Apr 2021 14:31:18 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9AC9160FE9 for ; Wed, 7 Apr 2021 14:31:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9AC9160FE9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=acm.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:Reply-To:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:Cc:To:From:Date:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=LOcfBt0r3lc7+DLvs6VJo97GCtIFBGtE40jCRV44sJ8=; b=GavS/REQ+JVUP2xBgkSmWAFWd kzX0rgcFZo0wqBlOa+9kECu68gqAQqwNpCrUZu5a+GGrutBcV7eSuZbgTxgI+itpM0JM69rk8LVqS RB4J5TTiQovjcwD9nGauleodJS0rjqIZSLEULzSYD84TEQtyPbZdyJmDMDeBGd/Qg6hp0HTYUkCk1 cCxfaT7G/PEjC417RJW75nOZKJq4I/mRgoDL0Hr31PtcoW57i9hg8doQCmT14oXflqLb+/E6HAgJS bHPU04GdS1EpTFCPZi1vebTTUA95gO0UIGRE8yxDkeBcStm6UZRKhBWDKQoRrQB++Cgq/5HSMC1jF tGzgt1THw==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lU9Ae-0058uR-JH; Wed, 07 Apr 2021 14:28:40 +0000 Received: from mail-ot1-x32b.google.com ([2607:f8b0:4864:20::32b]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lU9AX-0058s9-I4 for linux-arm-kernel@lists.infradead.org; Wed, 07 Apr 2021 14:28:36 +0000 Received: by mail-ot1-x32b.google.com with SMTP id c24-20020a9d6c980000b02902662e210895so17735311otr.9 for ; Wed, 07 Apr 2021 07:28:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:reply-to:references :mime-version:content-disposition:in-reply-to; bh=jOETYTM8063hIe+H5kFUr3hMwnez+idh/fGpidnkrFU=; b=LareH35xQvx6q7WindtheaqOLJg6+SkWSAntFgw7HjS3Tk4qDPoemJ1YOk85nmgPvg 9mZw56tpm53uQl29e+NuknOwYdP0xUGUxUvEzj64/Y7PD4nxPHMwswMAL8E4iHbcAhMx h0MdSnsyeyH4HD8RzChFdMtN/SVH7ahCvfGaZEIguKsC0HUgs97KIN7GkKUfnrLM2q+p MiRkxAMy9OTppt3tkoTAy1Zc4dPeODYOUi9GXRMbSxlEeRbbwdMytDy+G8hVjD1aj6yC LVzR9U89e8uevanQxmVqNCGOgMvZJvLBAuD6ahPOCf7aN31WHqeQdfIWyETLDQl2tc04 +zlg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :reply-to:references:mime-version:content-disposition:in-reply-to; bh=jOETYTM8063hIe+H5kFUr3hMwnez+idh/fGpidnkrFU=; b=A7mYmhPSm7MIF53JHM1gbRRYa+kTTKImnh6PyFpsB7ObCNzTb37kroBLu6SBRKpYv+ SihFaXG2CFPjjaiI+6X/XCUO2u5YE8t1RYgIMS2dajV6S/aC/vx/JEm3q55Z/X7XP4w7 RBUWMuGnhYMFtmpZP7Imntp54XCK6nVPaHrmfa4CQhV+guEHRTZ+3zPBneZuNT8t0BzK njK89pFQ25Lt/kZJnPfgb5GHCa2kHXe3F4JFmGMpae8ETXupSiyVlYVYw9KAJmAIrytV Y6RAK+OwUfKKAL9S+IymcP7RpB3f/khxFBt0W9bPQkqxn53LiPUgr4QElCSQ4BGLGNYW Z9rw== X-Gm-Message-State: AOAM533IgGMRZ2J4TQoVXBF0/EEBbGzkXm9rjqvQoVK5Qd7iK+GLWmVk SUGXFoUvNEVV2QZSGVV9kw== X-Google-Smtp-Source: ABdhPJxYDEUlP0EObBbm9VfamGrvC+u2TKkp/NeoRSzuuBtqMWkEEaA6ECIMT4B8dpnH6MIjEYoYqQ== X-Received: by 2002:a9d:37b4:: with SMTP id x49mr3212457otb.237.1617805711619; Wed, 07 Apr 2021 07:28:31 -0700 (PDT) Received: from serve.minyard.net (serve.minyard.net. [2001:470:b8f6:1b::1]) by smtp.gmail.com with ESMTPSA id h24sm5501853otg.20.2021.04.07.07.28.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Apr 2021 07:28:30 -0700 (PDT) Received: from minyard.net (unknown [IPv6:2001:470:b8f6:1b:f036:ecd9:2bd0:ef09]) by serve.minyard.net (Postfix) with ESMTPSA id 89595180570; Wed, 7 Apr 2021 14:28:29 +0000 (UTC) Date: Wed, 7 Apr 2021 09:28:28 -0500 From: Corey Minyard To: Quan Nguyen Cc: Rob Herring , Joel Stanley , Andrew Jeffery , Wolfram Sang , Philipp Zabel , openipmi-developer@lists.sourceforge.net, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, Open Source Submission , Phong Vo , "Thang Q . Nguyen" Subject: Re: [PATCH v2 0/3] Add Aspeed SSIF BMC driver Message-ID: <20210407142828.GE7166@minyard.net> References: <20210330141029.20412-1-quan@os.amperecomputing.com> <20210402142124.GV507977@minyard.net> <0e7fceff-4a01-5cb0-72eb-8b47d598f1c3@os.amperecomputing.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <0e7fceff-4a01-5cb0-72eb-8b47d598f1c3@os.amperecomputing.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210407_152833_858464_EC9EC372 X-CRM114-Status: GOOD ( 32.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: minyard@acm.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Apr 07, 2021 at 08:09:50PM +0700, Quan Nguyen wrote: > Hi Corey, > > Thank you for reviewing > I'll put my respond inline below. > > -Quan > > On 02/04/2021 21:21, Corey Minyard wrote: > > On Tue, Mar 30, 2021 at 09:10:26PM +0700, Quan Nguyen wrote: > > > This series add support for the Aspeed specific SSIF BMC driver which > > > is to perform in-band IPMI communication with the host in management > > > (BMC) side. > > > > I don't have any specific feedback for this, but I'm wondering if it's > > really necessary. > > > > Why can't the BMC just open the I2C device and use it? Is there any > > functionality that this provides that cannot be accomplished from > > userland access to the I2C device? I don't see any. > > > > If it tied into some existing framework to give abstract access to a BMC > > slave side interface, I'd be ok with this. But I don't see that. > > > > The SSIF at the BMC side acts as an I2C slave and we think that the kernel > driver is unavoidable to handle the I2c slave events > (https://www.kernel.org/doc/html/latest/i2c/slave-interface.html) > > And to make it works with existing OpenBMC IPMI stack, a userspace part, > ssifbridge, is needed (https://github.com/openbmc/ssifbridge). This > ssifbridge is to connect this driver with the OpenBMC IPMI stack so the IPMI > stack can communicate via SSIF channel in similar way that was implemented > with BT and KCS (ie: btbridge/kcsbridge and its corespondent kernel drivers > (https://github.com/openbmc/btbridge and > https://github.com/openbmc/kcsbridge)) Dang, I don't know why there's not a generic userland interface for the slave. And I've made this mistake before :(. Anyway, you are right, you need a driver. I'll review. -corey > > > Unless there is a big need to have this in the kernel, I'm against > > including this and would suggest you do all this work in userland. > > Perhaps write a library. Sorry, but I'm trying to do my part to reduce > > unnecessary things in the kernel. > > > > Thanks, > > > > -corey > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel