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=-10.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 12A35C433E0 for ; Mon, 29 Jun 2020 20:45:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD75720672 for ; Mon, 29 Jun 2020 20:45:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="jD0KhJNT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387956AbgF2UpY (ORCPT ); Mon, 29 Jun 2020 16:45:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731575AbgF2TN6 (ORCPT ); Mon, 29 Jun 2020 15:13:58 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E5CDC0147FF for ; Mon, 29 Jun 2020 01:25:18 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id u9so3205574pls.13 for ; Mon, 29 Jun 2020 01:25:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=i9Nqhif6ApfXooGjeibxstbXojwGjO9SaXuxe+uQjDQ=; b=jD0KhJNTqUUeR6j8mvpYmsiEJ6YBf4Q+GOdLtNpRkaBosp2KwiuK9yUwZ8EHRsFuai KYlaB4Q7zIBzB2CxHTakt+snj6JFm0zvArqsimL3CTVwFzg9kFc/0uJX+4EJSMKl78Bc YCiIqNCe1diXqPg7c6Mx/WhrlkN/DkzOY8IABTkcpPU92AXSVbkPxz+vgwWZCUWrwHAy HHm4m+xOl4bLGpYOv4MdVIYM7y+wGaHXjZXNn0ntnKRUnenNT2W/SkCtEoTHirw+Bicz 6AptWVdJlrnSBh25JHVXnbv+eT7UEvVvS4o5HLKaQ0MHyTc5UnqrtFjtTGM2izAw55it Xx3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=i9Nqhif6ApfXooGjeibxstbXojwGjO9SaXuxe+uQjDQ=; b=Jy0ayK36ypKeuNpgrgf6gzzKB/olcPzudgXXibayQfkLsqjwRmKKl0A746C1CHfoWL E5OAZ5TZv66v7az1KmJ705SfkuuFLecYWhwFnMrKjgb4DOxELxGOKQW1NXNjKzdObD5p MnC67bGzLLuq8FVcZiYpe9Wxi6QQ4PaV0Lf6V5nlMBO3iCPqvAjBn07oN1J5Q9W+SoYc GC6spvpowaTq1nYXEFCRh76NSO9IYmR4If6CjiCIPQHK08G1B6BUsrtAM7BuyIfW9NW7 z1n7UdovTSFSZoYScjKICcmEE5RZQ6saXOU94kDlRWJ029woGWWFWHYGYDUn/xZpGjwn PnHw== X-Gm-Message-State: AOAM5333Gj66jddTDuiJ81IMkzIi6kfOQJ5RnJAzABDQfvQh6FHWAEoA qs33v1bbfvXaaqlnWxG2ZnqzaQ== X-Google-Smtp-Source: ABdhPJySmY+y/vwIX7ZPHKRcm025SbC8nwl+OHt6zHB9pB5+zOoWeprGva6CTquPpjzuELrjdUDBrw== X-Received: by 2002:a17:90b:1492:: with SMTP id js18mr8390978pjb.42.1593419118010; Mon, 29 Jun 2020 01:25:18 -0700 (PDT) Received: from localhost ([122.172.127.76]) by smtp.gmail.com with ESMTPSA id 8sm19048210pja.0.2020.06.29.01.25.17 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 29 Jun 2020 01:25:17 -0700 (PDT) From: Viresh Kumar To: Rafael Wysocki , Jonathan Corbet , Viresh Kumar Cc: linux-pm@vger.kernel.org, Vincent Guittot , kernel-team@android.com, tkjos@google.com, adharmap@codeaurora.org, Quentin Perret , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V4 3/3] cpufreq: Specify default governor on command line Date: Mon, 29 Jun 2020 13:55:00 +0530 Message-Id: <96b6e6ca02b664194ff3e57e1ec768fbc597bf38.1593418662.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.25.0.rc1.19.g042ed3e048af In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org From: Quentin Perret Currently, the only way to specify the default CPUfreq governor is via Kconfig options, which suits users who can build the kernel themselves perfectly. However, for those who use a distro-like kernel (such as Android, with the Generic Kernel Image project), the only way to use a different default is to boot to userspace, and to then switch using the sysfs interface. Being able to specify the default governor on the command line, like is the case for cpuidle, would enable those users to specify their governor of choice earlier on, and to simplify slighlty the userspace boot procedure. To support this use-case, add a kernel command line parameter enabling to specify a default governor for CPUfreq, which takes precedence over the builtin default. This implementation has one notable limitation: the default governor must be registered before the driver. This is solved for builtin governors and drivers using appropriate *_initcall() functions. And in the modular case, this must be reflected as a constraint on the module loading order. Signed-off-by: Quentin Perret [ Viresh: Converted 'default_governor' to a string and parsing it only at initcall level, and several updates to cpufreq_init_policy(). ] Signed-off-by: Viresh Kumar --- .../admin-guide/kernel-parameters.txt | 5 +++ Documentation/admin-guide/pm/cpufreq.rst | 6 ++-- drivers/cpufreq/cpufreq.c | 31 +++++++++++++------ 3 files changed, 30 insertions(+), 12 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb95fad81c79..8deb5a89328a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -703,6 +703,11 @@ cpufreq.off=1 [CPU_FREQ] disable the cpufreq sub-system + cpufreq.default_governor= + [CPU_FREQ] Name of the default cpufreq governor or + policy to use. This governor must be registered in the + kernel before the cpufreq driver probes. + cpu_init_udelay=N [X86] Delay for N microsec between assert and de-assert of APIC INIT to start processors. This delay occurs diff --git a/Documentation/admin-guide/pm/cpufreq.rst b/Documentation/admin-guide/pm/cpufreq.rst index 0c74a7784964..368e612145d2 100644 --- a/Documentation/admin-guide/pm/cpufreq.rst +++ b/Documentation/admin-guide/pm/cpufreq.rst @@ -147,9 +147,9 @@ CPUs in it. The next major initialization step for a new policy object is to attach a scaling governor to it (to begin with, that is the default scaling governor -determined by the kernel configuration, but it may be changed later -via ``sysfs``). First, a pointer to the new policy object is passed to the -governor's ``->init()`` callback which is expected to initialize all of the +determined by the kernel command line or configuration, but it may be changed +later via ``sysfs``). First, a pointer to the new policy object is passed to +the governor's ``->init()`` callback which is expected to initialize all of the data structures necessary to handle the given policy and, possibly, to add a governor ``sysfs`` interface to it. Next, the governor is started by invoking its ``->start()`` callback. diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index e9e8200a0211..ad94b1d47ddb 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -50,6 +50,8 @@ static LIST_HEAD(cpufreq_governor_list); #define for_each_governor(__governor) \ list_for_each_entry(__governor, &cpufreq_governor_list, governor_list) +static char default_governor[CPUFREQ_NAME_LEN]; + /** * The "cpufreq driver" - the arch- or hardware-dependent low * level driver of CPUFreq support, and its spinlock. This lock @@ -1061,7 +1063,6 @@ __weak struct cpufreq_governor *cpufreq_default_governor(void) static int cpufreq_init_policy(struct cpufreq_policy *policy) { - struct cpufreq_governor *def_gov = cpufreq_default_governor(); struct cpufreq_governor *gov = NULL; unsigned int pol = CPUFREQ_POLICY_UNKNOWN; int ret; @@ -1071,21 +1072,27 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy) gov = get_governor(policy->last_governor); if (gov) { pr_debug("Restoring governor %s for cpu %d\n", - policy->governor->name, policy->cpu); - } else if (def_gov) { - gov = def_gov; - __module_get(gov->owner); + gov->name, policy->cpu); } else { - return -ENODATA; + gov = get_governor(default_governor); + } + + if (!gov) { + gov = cpufreq_default_governor(); + if (!gov) + return -ENODATA; + __module_get(gov->owner); } + } else { + /* Use the default policy if there is no last_policy. */ if (policy->last_policy) { pol = policy->last_policy; - } else if (def_gov) { - pol = cpufreq_parse_policy(def_gov->name); + } else { + pol = cpufreq_parse_policy(default_governor); /* - * In case the default governor is neiter "performance" + * In case the default governor is neither "performance" * nor "powersave", fall back to the initial policy * value set by the driver. */ @@ -2795,13 +2802,19 @@ EXPORT_SYMBOL_GPL(cpufreq_unregister_driver); static int __init cpufreq_core_init(void) { + struct cpufreq_governor *gov = cpufreq_default_governor(); + if (cpufreq_disabled()) return -ENODEV; cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj); BUG_ON(!cpufreq_global_kobject); + if (!strlen(default_governor)) + strncpy(default_governor, gov->name, CPUFREQ_NAME_LEN); + return 0; } module_param(off, int, 0444); +module_param_string(default_governor, default_governor, CPUFREQ_NAME_LEN, 0444); core_initcall(cpufreq_core_init); -- 2.25.0.rc1.19.g042ed3e048af