From patchwork Tue Jun 23 14:21:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quentin Perret X-Patchwork-Id: 211761 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=-17.6 required=3.0 tests=DKIMWL_WL_MED, 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, USER_IN_DEF_DKIM_WL 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 6358AC433E0 for ; Tue, 23 Jun 2020 14:21:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3B9202072E for ; Tue, 23 Jun 2020 14:21:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="L+PgZpf1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732738AbgFWOVs (ORCPT ); Tue, 23 Jun 2020 10:21:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53322 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732769AbgFWOVq (ORCPT ); Tue, 23 Jun 2020 10:21:46 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 32D8FC061573 for ; Tue, 23 Jun 2020 07:21:45 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id b135so24206180yba.11 for ; Tue, 23 Jun 2020 07:21:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=3FVZM6YK4WuItfsUzRuxaLQpo5idX99+ykpcHtbDxao=; b=L+PgZpf1ipA1/ahUV409sUxMwe9aXxIjms47WLR6AQumOcds1mlpb4KHQjOh8mUJos ZKooyOz/cW31DiK0jFqsCvhBDbK+LojeLU3VpOWEiavltM4rgbl5NtOQfDibxiUb4bLK 4cu7P+h9YaxCtzDv/VSqgajZUcfnZX9KGphTkGSNAHsfwG40AtJ+uPy5Q4A5pZX1VkQv HkSEHOt21LFJRvA0k6k8RJs/SRMLYTpA+k3+vtbJ/I5AM/Tzs6lU3XHFxhLqsIJoOZ2L jyAwAuUNB1/nKjmUCnnvuJQfWJYAz86jtWt4Pmm/pbjnGeSnnqmuqvXuCPWs3SkxsM7Q 6UHA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=3FVZM6YK4WuItfsUzRuxaLQpo5idX99+ykpcHtbDxao=; b=aE3LtQmLZG+1WOHKjlWE/Rx5bYnG7waPisKLIhDbtBEqCfSnLlWjeu7oDXYhjW5Uyy xpEJOO5S0n27iWm678jbnEugyLKa+71Y54NMcFpTOaWDxa1gseE+M8BnywDcgWcALv7l 3BdlxiuvxyDeQZM4ib2ee3KVps+PfD2EHZB1HmVG96e35qCAhJ2Yzh/L2Z3IYQT8uACj IigGZ0NmyqYfAjUKVWRUiCo8jfGYoBdaaZcjz8DiwCNxl/2sbz1ZfDKO9BYWoZ0XT03Y cbFjfDSP//RfMkkzMoX5Pe3ISI0MTPhtZHaNQTkktUAQ/UV0PFBBrAJ6APqWY777F608 YyJw== X-Gm-Message-State: AOAM531ZetZ7Zbbwy4u/4/LUBHT13vuotgW5qdkG0KmcHQfOAcnlLVNP FMfvvBxigDi4w++dfEbr8cMzsI+JGs0Y X-Google-Smtp-Source: ABdhPJwxz7yaVNFBCa7KewRziQgnrBazx0rNXq0015FvhEtCqD12iPNPYMWA9BTVzY0JbqD3X0mIRc8+ZLeM X-Received: by 2002:a25:54e:: with SMTP id 75mr35259783ybf.222.1592922104320; Tue, 23 Jun 2020 07:21:44 -0700 (PDT) Date: Tue, 23 Jun 2020 15:21:38 +0100 In-Reply-To: <20200623142138.209513-1-qperret@google.com> Message-Id: <20200623142138.209513-3-qperret@google.com> Mime-Version: 1.0 References: <20200623142138.209513-1-qperret@google.com> X-Mailer: git-send-email 2.27.0.111.gc72c7da667-goog Subject: [PATCH v2 2/2] cpufreq: Specify default governor on command line From: Quentin Perret To: rjw@rjwysocki.net, rafael@kernel.org, viresh.kumar@linaro.org Cc: arnd@arndb.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, kernel-team@android.com, qperret@google.com, tkjos@google.com, adharmap@codeaurora.org Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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 --- .../admin-guide/kernel-parameters.txt | 5 ++++ Documentation/admin-guide/pm/cpufreq.rst | 6 ++--- drivers/cpufreq/cpufreq.c | 23 +++++++++++++++---- 3 files changed, 26 insertions(+), 8 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index fb95fad81c79..5fd3c9f187eb 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 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 0128de3603df..4b1a5c0173cf 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -50,6 +50,9 @@ static LIST_HEAD(cpufreq_governor_list); #define for_each_governor(__governor) \ list_for_each_entry(__governor, &cpufreq_governor_list, governor_list) +static char cpufreq_param_governor[CPUFREQ_NAME_LEN]; +static struct cpufreq_governor *default_governor; + /** * The "cpufreq driver" - the arch- or hardware-dependent low * level driver of CPUFreq support, and its spinlock. This lock @@ -1055,7 +1058,6 @@ __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; @@ -1065,8 +1067,8 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy) if (gov) { pr_debug("Restoring governor %s for cpu %d\n", policy->governor->name, policy->cpu); - } else if (def_gov) { - gov = def_gov; + } else if (default_governor) { + gov = default_governor; } else { return -ENODATA; } @@ -1074,8 +1076,8 @@ static int cpufreq_init_policy(struct cpufreq_policy *policy) /* 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 if (default_governor) { + pol = cpufreq_parse_policy(default_governor->name); /* * In case the default governor is neiter "performance" * nor "powersave", fall back to the initial policy @@ -2320,6 +2322,9 @@ int cpufreq_register_governor(struct cpufreq_governor *governor) list_add(&governor->governor_list, &cpufreq_governor_list); } + if (!strncasecmp(cpufreq_param_governor, governor->name, CPUFREQ_NAME_LEN)) + default_governor = governor; + mutex_unlock(&cpufreq_governor_mutex); return err; } @@ -2348,6 +2353,8 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor) mutex_lock(&cpufreq_governor_mutex); list_del(&governor->governor_list); + if (governor == default_governor) + default_governor = cpufreq_default_governor(); mutex_unlock(&cpufreq_governor_mutex); } EXPORT_SYMBOL_GPL(cpufreq_unregister_governor); @@ -2789,7 +2796,13 @@ static int __init cpufreq_core_init(void) cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj); BUG_ON(!cpufreq_global_kobject); + mutex_lock(&cpufreq_governor_mutex); + if (!default_governor) + default_governor = cpufreq_default_governor(); + mutex_unlock(&cpufreq_governor_mutex); + return 0; } module_param(off, int, 0444); +module_param_string(default_governor, cpufreq_param_governor, CPUFREQ_NAME_LEN, 0444); core_initcall(cpufreq_core_init);