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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 4164DC433E0 for ; Wed, 20 May 2020 07:33:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D688207D3 for ; Wed, 20 May 2020 07:33:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589959993; bh=wubkXTV9YfNSZFkVpKAM6nS+N7G81auN5xKELhErTmY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=gfw3+rDlpH+JJNrZJFdQzB2mKdrAbI+Eobwj1yZCIm7JgI7OfKXSI+k16oK4WpRA5 sTUvKKGvtLEf5WZXLPRmkYECjmEJ778zHBCNftYYgOjPVd6mA2qm2A11L+HMTNHwdl tXIFa+KOaRt3+CiKNvXkn2ZPzTuYVfu7cSzs+fK4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726752AbgETHdL (ORCPT ); Wed, 20 May 2020 03:33:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:58988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726309AbgETHdK (ORCPT ); Wed, 20 May 2020 03:33:10 -0400 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 26ABF205CB; Wed, 20 May 2020 07:33:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589959989; bh=wubkXTV9YfNSZFkVpKAM6nS+N7G81auN5xKELhErTmY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=yc/605SUMUJFs9TJLBPK2N5ck7U+Xa/E8+UxOiI7rgE3jsziwIwsk2ilHury9s9E2 pTi8zsr9ZsOdemB7gI4Lu3oSp6U9/zDqz0PuAkVPzm4Smr6sumxAV0qmwbH5wb3vON SxPzkYN+kKYXfWbahrcv+B36uCRmn6Sj+4UJgtoU= Date: Wed, 20 May 2020 08:33:04 +0100 From: Will Deacon To: Rob Herring Cc: Joakim Zhang , john.garry@huawei.com, mark.rutland@arm.com, shawnguo@kernel.org, linux-imx@nxp.com, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace Message-ID: <20200520073304.GA23534@willie-the-truck> References: <20200512073115.14177-1-qiangqing.zhang@nxp.com> <20200512073115.14177-2-qiangqing.zhang@nxp.com> <20200519185125.GB453195@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200519185125.GB453195@bogus> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Will [1] https://lore.kernel.org/r/1587120634-19666-1-git-send-email-john.garry@huawei.com