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=-2.3 required=3.0 tests=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 907BAC433DF for ; Thu, 21 May 2020 14:17:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EFBF20721 for ; Thu, 21 May 2020 14:17:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729658AbgEUORc (ORCPT ); Thu, 21 May 2020 10:17:32 -0400 Received: from lhrrgout.huawei.com ([185.176.76.210]:2239 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727909AbgEUORb (ORCPT ); Thu, 21 May 2020 10:17:31 -0400 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id B7AC5851A8F64C7CAB12; Thu, 21 May 2020 15:17:29 +0100 (IST) Received: from [127.0.0.1] (10.47.6.132) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Thu, 21 May 2020 15:17:28 +0100 Subject: Re: [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace To: Mark Rutland , Will Deacon CC: Rob Herring , Joakim Zhang , , , , , References: <20200512073115.14177-1-qiangqing.zhang@nxp.com> <20200512073115.14177-2-qiangqing.zhang@nxp.com> <20200519185125.GB453195@bogus> <20200520073304.GA23534@willie-the-truck> <20200521132641.GB47848@C02TD0UTHF1T.local> From: John Garry Message-ID: <04e6ed82-d33e-9153-eeab-29986ccf8e1e@huawei.com> Date: Thu, 21 May 2020 15:16:29 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20200521132641.GB47848@C02TD0UTHF1T.local> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.6.132] X-ClientProxiedBy: lhreml715-chm.china.huawei.com (10.201.108.66) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/05/2020 14:26, Mark Rutland wrote: > On Wed, May 20, 2020 at 08:33:04AM +0100, Will Deacon wrote: >> On Tue, May 19, 2020 at 12:51:25PM -0600, Rob Herring wrote: >>> On Tue, May 12, 2020 at 03:31:13PM +0800, Joakim Zhang wrote: >>>> +static ssize_t ddr_perf_identifier_show(struct device *dev, >>>> + struct device_attribute *attr, >>>> + char *page) >>>> +{ >>>> + struct ddr_pmu *pmu = dev_get_drvdata(dev); >>>> + >>>> + return sprintf(page, "%s\n", pmu->devtype_data->identifier); >>> >>> Why do we need yet another way to identify the SoC from userspace? >> >> I also really dislike this. What's the preferred way to identify the SoC >> from userspace? It's needed so that the perf userspace tool can describe >> perf events that are supported for the PMU, as this isn't probe-able >> directly from the hardware. We have the same issue with the SMMUv3 PMCG [1], >> and so we need to solve the problem for both DT and ACPI. > > Worth noting that while in this case it happens to identify the SoC, > in general you can have distinct instances of system IP in a single > system, so I do think that we need *something* instance-specific, even > if that's combined with SoC info. > Hi Mark, > Where IP gets reused across SoCs, it makes sense for that to not depend > on top-level SoC info. This would be quite an uncommon case. Generally most instances of a given PMU in a SoC would be identical implementations. And anyway, we should be able to solve that problem in perf tool, as long as the PMU device name is fixed. Like what we have for the SMMUv3 PMU, where the device name contains the device bus address, i.e don't use idr for perf drivers device naming.... Thanks, John 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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 5C5D3C433E0 for ; Thu, 21 May 2020 14:18:00 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 26EAD20721 for ; Thu, 21 May 2020 14:18:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="NxM9vKfn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 26EAD20721 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+infradead-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=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding: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=EWhsIHwTOdvI65sM6NtK+nAXjzAYfVFbV6Z98MLys9I=; b=NxM9vKfne083PaLQso8WpEhEX eUZX2fJbOd6q4Seh9CnFH838Y7Fe452w4bgZGzn1+9rGgzoH1e8m4cDA5KNIvJrbbsgcCl7y1UiLJ 9EQyvCMzPQBmoUtoQYG2EiexKmfh53uFz1u6JU+wB5WRBCtJx6CZffuBaWlPV+f8nkZyo2A+lEUcp RlucoKhvBqTRmZnupEJCm7OJsRfVwmj8rtxkWR53OX3eSnfsaX6Jrv0a5CuEr2BUPXxvdMQ3L74T2 EsBTKkCIip69svvB1qCCP6831DW/xLxOU5kKRhPgrq9WC1UQ/BgLMulZO5IqKQtmFDnjwfSrbIZNR 7MBxO9QDQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbm1G-0002Fp-V7; Thu, 21 May 2020 14:17:58 +0000 Received: from lhrrgout.huawei.com ([185.176.76.210] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbm0q-0001vP-EN for linux-arm-kernel@lists.infradead.org; Thu, 21 May 2020 14:17:36 +0000 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.108]) by Forcepoint Email with ESMTP id B7AC5851A8F64C7CAB12; Thu, 21 May 2020 15:17:29 +0100 (IST) Received: from [127.0.0.1] (10.47.6.132) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1913.5; Thu, 21 May 2020 15:17:28 +0100 Subject: Re: [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace To: Mark Rutland , Will Deacon References: <20200512073115.14177-1-qiangqing.zhang@nxp.com> <20200512073115.14177-2-qiangqing.zhang@nxp.com> <20200519185125.GB453195@bogus> <20200520073304.GA23534@willie-the-truck> <20200521132641.GB47848@C02TD0UTHF1T.local> From: John Garry Message-ID: <04e6ed82-d33e-9153-eeab-29986ccf8e1e@huawei.com> Date: Thu, 21 May 2020 15:16:29 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: <20200521132641.GB47848@C02TD0UTHF1T.local> Content-Language: en-US X-Originating-IP: [10.47.6.132] X-ClientProxiedBy: lhreml715-chm.china.huawei.com (10.201.108.66) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200521_071732_691865_5C4E6709 X-CRM114-Status: GOOD ( 15.53 ) 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: Rob Herring , devicetree@vger.kernel.org, Joakim Zhang , linux-kernel@vger.kernel.org, linux-imx@nxp.com, shawnguo@kernel.org, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 21/05/2020 14:26, Mark Rutland wrote: > On Wed, May 20, 2020 at 08:33:04AM +0100, Will Deacon wrote: >> On Tue, May 19, 2020 at 12:51:25PM -0600, Rob Herring wrote: >>> On Tue, May 12, 2020 at 03:31:13PM +0800, Joakim Zhang wrote: >>>> +static ssize_t ddr_perf_identifier_show(struct device *dev, >>>> + struct device_attribute *attr, >>>> + char *page) >>>> +{ >>>> + struct ddr_pmu *pmu = dev_get_drvdata(dev); >>>> + >>>> + return sprintf(page, "%s\n", pmu->devtype_data->identifier); >>> >>> Why do we need yet another way to identify the SoC from userspace? >> >> I also really dislike this. What's the preferred way to identify the SoC >> from userspace? It's needed so that the perf userspace tool can describe >> perf events that are supported for the PMU, as this isn't probe-able >> directly from the hardware. We have the same issue with the SMMUv3 PMCG [1], >> and so we need to solve the problem for both DT and ACPI. > > Worth noting that while in this case it happens to identify the SoC, > in general you can have distinct instances of system IP in a single > system, so I do think that we need *something* instance-specific, even > if that's combined with SoC info. > Hi Mark, > Where IP gets reused across SoCs, it makes sense for that to not depend > on top-level SoC info. This would be quite an uncommon case. Generally most instances of a given PMU in a SoC would be identical implementations. And anyway, we should be able to solve that problem in perf tool, as long as the PMU device name is fixed. Like what we have for the SMMUv3 PMU, where the device name contains the device bus address, i.e don't use idr for perf drivers device naming.... Thanks, John _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel