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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 D3787C33CA2 for ; Fri, 10 Jan 2020 12:28:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B085E2077C for ; Fri, 10 Jan 2020 12:28:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728160AbgAJM2u (ORCPT ); Fri, 10 Jan 2020 07:28:50 -0500 Received: from foss.arm.com ([217.140.110.172]:43930 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728029AbgAJM2t (ORCPT ); Fri, 10 Jan 2020 07:28:49 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A5DC71063; Fri, 10 Jan 2020 04:28:48 -0800 (PST) Received: from [192.168.1.123] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 41AA83F534; Fri, 10 Jan 2020 04:28:47 -0800 (PST) Subject: Re: [PATCH v1] arch_topology: Adjust initial CPU capacities with current freq To: Dietmar Eggemann , Sudeep Holla , Jeffy Chen Cc: linux-kernel@vger.kernel.org, Brian Norris , Marc Zyngier , Douglas Anderson , Heiko Stuebner , Greg Kroah-Hartman , "Rafael J. Wysocki" References: <20200109075214.31943-1-jeffy.chen@rock-chips.com> <20200110113711.GB39451@bogus> <5475692c-e72b-74c1-bd6e-95278703249b@arm.com> From: Robin Murphy Message-ID: <15ab46e5-a2b4-eb96-1217-2b2ef8827f64@arm.com> Date: Fri, 10 Jan 2020 12:28:46 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <5475692c-e72b-74c1-bd6e-95278703249b@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-01-10 12:01 pm, Dietmar Eggemann wrote: > On 10/01/2020 12:37, Sudeep Holla wrote: >> On Thu, Jan 09, 2020 at 03:52:14PM +0800, Jeffy Chen wrote: >>> The CPU freqs are not supposed to change before cpufreq policies >>> properly registered, meaning that they should be used to calculate the >>> initial CPU capacities. >>> >>> Doing this helps choosing the best CPU during early boot, especially >>> for the initramfs decompressing. >>> >>> Signed-off-by: Jeffy Chen >> >> [...] >> >>> @@ -146,10 +153,15 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu) >>> return false; >>> } >>> } >>> - capacity_scale = max(cpu_capacity, capacity_scale); >>> raw_capacity[cpu] = cpu_capacity; >>> pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n", >>> cpu_node, raw_capacity[cpu]); >>> + >>> + cpu_clk = of_clk_get(cpu_node, 0); >>> + if (!PTR_ERR_OR_ZERO(cpu_clk)) >>> + per_cpu(max_freq, cpu) = clk_get_rate(cpu_clk) / 1000; >>> + >>> + clk_put(cpu_clk); >> >> I don't like to assume DVFS to be supplied only using 'clk'. So NACK! >> We have other non-clk mechanism for CPU DVFS and this needs to simply >> use cpufreq APIs to get frequency value if required. > > To support this, it's failing on my Arm64 Juno board. > > ... > [ 0.084858] CPU1 cpu_clk=-517 > [ 0.087961] CPU2 cpu_clk=-517 > [ 0.091005] CPU0 cpu_clk=-517 > [ 0.094121] CPU3 cpu_clk=-517 > [ 0.097248] CPU4 cpu_clk=-517 > [ 0.100415] CPU5 cpu_clk=-517 > ... > > Since you're on a big.LITTLE platform, did you specify > 'capacity-dmips-mhz' for CPUs to be able to distinguish big and little > CPUs before CPUfreq kicks in? Indeed, and that's the "problem" - the capacities are there, but with the broken firmware the kernel starts with the little (boot) cluster clocked at either 400 or 200MHz, but the big cluster at just 12MHz. At that speed, a full distro config can take about 3 minutes to get to the point of loading cpufreq as a module, and I've seen at least one distro reverting 97df3aa76b4a to 'fix' the symptom :( Robin. > > $ grep capacity-dmips-mhz ./arch/arm64/boot/dts/arm/juno.dts > capacity-dmips-mhz = <1024>; > capacity-dmips-mhz = <1024>; > capacity-dmips-mhz = <578>; > capacity-dmips-mhz = <578>; > capacity-dmips-mhz = <578>; > capacity-dmips-mhz = <578>; >