From patchwork Mon Jun 15 16:55:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Quentin Perret X-Patchwork-Id: 11605443 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 43E3914E3 for ; Mon, 15 Jun 2020 16:56:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2592920836 for ; Mon, 15 Jun 2020 16:56:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="cuJ222JF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731015AbgFOQ4E (ORCPT ); Mon, 15 Jun 2020 12:56:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729628AbgFOQ4D (ORCPT ); Mon, 15 Jun 2020 12:56:03 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 63FBDC05BD43 for ; Mon, 15 Jun 2020 09:56:02 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id t18so14720076qke.8 for ; Mon, 15 Jun 2020 09:56:02 -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=rmttyKz0sTdI4/Wk+GTFfxu2WU1sGb9iqnCsy3KIwVE=; b=cuJ222JFgG6Wav6PHDylftDoc7puvRPmG+8eTu72bSGUEDOtWWfL4+qfs6opmi6DwM k4fhKoIQPuntLywxeo0hKhCsK4qsCMCRBF9tXG4SMjRayA2OsSVe2gtEohxjRthTVwsg 2PRIQ+MXqxwI7h7FPzvHSRwfcVFwqQIfAQ6fhzP6emUXWKLfQCdRtQUVR1SixDh2VnUZ kbeu7Uwf9js422PujgnJcqmE/g3U4No3d/Pk+2Y9V8Z8/6B/5B+0a93k9ivzVPoe67O9 rYMK+R/DUuGXU5RI1/kRC4kPtS7CMq8C5b+vJH5vEJ0fR1ZG7DUOx3RL1ptqOLpng+bP nBzg== 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=rmttyKz0sTdI4/Wk+GTFfxu2WU1sGb9iqnCsy3KIwVE=; b=W0E1P8slLWf63/t5zzhONS0821ouugJ7XwnMKIBLg3G1RXKlRRqSwOGLv3/U7DDXn5 65f9RRFPJph2JK7qAXPRDpsgu5buDjoClfmNYnp+f05OJ/9E/l8vxFA8dztFJxJawPGK Xh/mXhtIyzPj3nTvqJFjHhwjfWvtg0iB32Pdq85YDsQM8YyQm/WCqqh0FCCCAYsuWG9P AnjrF8afBwGp7vBON7e+5VSAnMFoLsRsGXB/qmee2oEiuyrlpg7GCjGV1mPFM0R0jxZK 67aEOPJZf2AON6qU2zhG39iMeBpKRcf1rhRh2qRakUGNGOuJHXhluraHEePyHmtkBb2u nVNw== X-Gm-Message-State: AOAM5338kF65FItmG97pU57HG+Uh1wU2Zf6KntNj0hORSQNVeyZVu0Nq iuQ3uQ92EQe1CEozaT92h5nF4BPxnXgQ X-Google-Smtp-Source: ABdhPJxu0sj2E89tKcmQTaKcRjumvWg2bCjfwFUYPI2vq1B6zd2GBouCZQ6YlWOEiSqJmqO1hAUpGCE4vThl X-Received: by 2002:ad4:43c8:: with SMTP id o8mr26494403qvs.235.1592240161344; Mon, 15 Jun 2020 09:56:01 -0700 (PDT) Date: Mon, 15 Jun 2020 17:55:54 +0100 In-Reply-To: <20200615165554.228063-1-qperret@google.com> Message-Id: <20200615165554.228063-3-qperret@google.com> Mime-Version: 1.0 References: <20200615165554.228063-1-qperret@google.com> X-Mailer: git-send-email 2.27.0.290.gba653c62da-goog Subject: [PATCH 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 | 34 ++++++++++++++++--- 3 files changed, 37 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..0f05caedc320 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 @@ -2196,6 +2198,24 @@ __weak struct cpufreq_governor *cpufreq_fallback_governor(void) return NULL; } +static void cpufreq_get_default_governor(void) +{ + default_governor = cpufreq_parse_governor(cpufreq_param_governor); + if (!default_governor) { + if (*cpufreq_param_governor) + pr_warn("Failed to find %s\n", cpufreq_param_governor); + default_governor = cpufreq_default_governor(); + } +} + +static void cpufreq_put_default_governor(void) +{ + if (!default_governor) + return; + module_put(default_governor->owner); + default_governor = NULL; +} + static int cpufreq_init_governor(struct cpufreq_policy *policy) { int ret; @@ -2701,6 +2721,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (driver_data->setpolicy) driver_data->flags |= CPUFREQ_CONST_LOOPS; + else + cpufreq_get_default_governor(); if (cpufreq_boost_supported()) { ret = create_boost_sysfs_file(); @@ -2769,6 +2791,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver) subsys_interface_unregister(&cpufreq_interface); remove_boost_sysfs_file(); cpuhp_remove_state_nocalls_cpuslocked(hp_online); + cpufreq_put_default_governor(); write_lock_irqsave(&cpufreq_driver_lock, flags); @@ -2792,4 +2815,5 @@ static int __init cpufreq_core_init(void) return 0; } module_param(off, int, 0444); +module_param_string(default_governor, cpufreq_param_governor, CPUFREQ_NAME_LEN, 0444); core_initcall(cpufreq_core_init);