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,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 E93AFC433E0 for ; Thu, 21 May 2020 14:01:28 +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 AB9D820748 for ; Thu, 21 May 2020 14:01:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="tKdiljQO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB9D820748 Authentication-Results: mail.kernel.org; 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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 1jbllI-0007fp-AH; Thu, 21 May 2020 14:01:28 +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 1jbllF-0007f5-7P for linux-arm-kernel@lists.infradead.org; Thu, 21 May 2020 14:01:26 +0000 Received: from lhreml724-chm.china.huawei.com (unknown [172.18.7.107]) by Forcepoint Email with ESMTP id 3CC2F38420F11539B82D; Thu, 21 May 2020 15:01:14 +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 15:01:13 +0100 Subject: Re: [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace To: Will Deacon , Rob Herring References: <20200512073115.14177-1-qiangqing.zhang@nxp.com> <20200512073115.14177-2-qiangqing.zhang@nxp.com> <20200519185125.GB453195@bogus> <20200520073304.GA23534@willie-the-truck> <20200521130415.GB5949@willie-the-truck> From: John Garry Message-ID: Date: Thu, 21 May 2020 15:00:13 +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: <20200521130415.GB5949@willie-the-truck> 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_070125_411774_4B1E18EC X-CRM114-Status: GOOD ( 14.52 ) 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: Mark Rutland , devicetree@vger.kernel.org, Joakim Zhang , "linux-kernel@vger.kernel.org" , NXP Linux Team , Shawn Guo , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 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 14:04, Will Deacon wrote: > On Wed, May 20, 2020 at 09:23:41AM -0600, Rob Herring wrote: >> On Wed, May 20, 2020 at 1:33 AM 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? >> >> /proc/cpuinfo? ;) > > The *SoC*! > >> For an non-firmware specific case, I'd say soc_device should be. I'd >> guess ACPI systems don't use it and for them it's dmidecode typically. >> The other problem I have with soc_device is it is optional. > Hi Will, > John -- what do you think about using soc_device to expose this information, > with ACPI systems using DMI data instead? Generally I don't think that DMI is reliable, and I saw this as the least preferred choice. I'm looking at the sysfs DMI info for my dev board, and I don't even see anything like a SoC identifier. As for the event_source device sysfs identifier file, it would not always contain effectively the same as the SoC ID. Certain PMUs which I'm interested in plan to have probe-able identification info available in future. Thanks, John _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel