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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 3FD0FC433E0 for ; Sat, 30 Jan 2021 01:36:40 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 C231564DBD for ; Sat, 30 Jan 2021 01:36:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C231564DBD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com 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=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=c5J48Ljj93Eq+V5+kONCnK6KDf9Zczd87B5yGwRuIlY=; b=CXuOjyCCRorbT0amqzVW3gD4b /Zqb1/fACgsPmNxVQ5I03Jle4lFWRLM1oKuBnLUDgpeXaD5VQzzsueENv07MVIqsZ58HotHwPkKea lxavYOIWMD9JywoRMJmavmP9y5IsZkaFw+hv4+kXDXMOgiSs21P0u1OREujkn77/axOjuVTispOfk FTkZagWaDorsbrU8rKuMZajSW7ux+f9kYolgMfmEWslnB6VgIynDlInkWhbjS7GPWU63a5kPefj3b oRcLMY0zQe8yUzZflldBWk+Y3gFny3j6BJnmdM63A4K83I8GWcGOIz8p6qt/blLjw2sprdjvpLY4z FKNH1yU8g==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5fAQ-0003mX-TC; Sat, 30 Jan 2021 01:35:14 +0000 Received: from szxga07-in.huawei.com ([45.249.212.35]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l5fAN-0003m4-LM for linux-arm-kernel@lists.infradead.org; Sat, 30 Jan 2021 01:35:13 +0000 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga07-in.huawei.com (SkyGuard) with ESMTP id 4DSGvK0yY4z7d2C; Sat, 30 Jan 2021 09:33:49 +0800 (CST) Received: from [127.0.0.1] (10.174.176.220) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.498.0; Sat, 30 Jan 2021 09:34:56 +0800 Subject: Re: [PATCH v3 2/3] perf/smmuv3: Add a MODULE_SOFTDEP() to indicate dependency on SMMU To: Robin Murphy , John Garry , Will Deacon , Mark Rutland , "Joerg Roedel" , linux-arm-kernel , iommu , linux-kernel References: <20210127113258.1421-1-thunder.leizhen@huawei.com> <20210127113258.1421-3-thunder.leizhen@huawei.com> <67e0859b-2633-3516-527f-57557e210fa1@arm.com> <4b116f38-84da-9ef9-350c-8900944b0433@huawei.com> From: "Leizhen (ThunderTown)" Message-ID: Date: Sat, 30 Jan 2021 09:34:55 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.174.176.220] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210129_203512_016551_878DF38E X-CRM114-Status: GOOD ( 14.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jean-Philippe Brucker 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 2021/1/30 1:03, Robin Murphy wrote: > On 2021-01-29 15:34, John Garry wrote: >> On 29/01/2021 15:12, Robin Murphy wrote: >>> On 2021-01-27 11:32, Zhen Lei wrote: >>>> The MODULE_SOFTDEP() gives user space a hint of the loading sequence. And >>>> when command "modprobe arm_smmuv3_pmu" is executed, the arm_smmu_v3.ko is >>>> automatically loaded in advance. >>> >>> Why do we need this? If probe order doesn't matter when both drivers are built-in, why should module load order? >>> >>> TBH I'm not sure why we even have a Kconfig dependency on ARM_SMMU_V3, given that the drivers operate completely independently :/ >> >> Can that Kconfig dependency just be removed? I think that it was added under the idea that there is no point in having the SMMUv3 PMU driver without the SMMUv3 driver. > > A PMCG *might* be usable for simply counting transactions to measure device activity regardless of its associated SMMU being enabled. If that's the case, the SOFTDEP really shouldn't be added. I wasn't trying to make sure they were loaded in order, just to make sure that the SMMU was not forgotten to load. > Either way, it's not really Kconfig's job to decide what makes sense (beyond the top-level "can this driver *ever* be used on this platform" visibility choices). Imagine if we gave every PCI/USB/etc. device driver an explicit ?dependency on at least one host controller driver being enabled... > > Robin. > > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel