Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758726AbcCDDhv (ORCPT ); Thu, 3 Mar 2016 22:37:51 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:49757 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755120AbcCDDfB (ORCPT ); Thu, 3 Mar 2016 22:35:01 -0500 From: "Rafael J. Wysocki" To: Linux PM list Cc: Juri Lelli , Steve Muckle , ACPI Devel Maling List , Linux Kernel Mailing List , Peter Zijlstra , Srinivas Pandruvada , Viresh Kumar , Vincent Guittot , Michael Turquette , Ingo Molnar Subject: [PATCH v2 6/10] cpufreq: Support for fast frequency switching Date: Fri, 04 Mar 2016 04:07:04 +0100 Message-ID: <15684081.T4iOMUSHCY@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/4.5.0-rc1+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <2409306.qzzMXcm4dm@vostro.rjw.lan> References: <2495375.dFbdlAZmA6@vostro.rjw.lan> <2409306.qzzMXcm4dm@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6656 Lines: 178 From: Rafael J. Wysocki Modify the ACPI cpufreq driver to provide a method for switching CPU frequencies from interrupt context and update the cpufreq core to support that method if available. Introduce a new cpufreq driver callback, ->fast_switch, to be invoked for frequency switching from interrupt context via a new helper function, cpufreq_driver_fast_switch(). Add a new policy flag, fast_switch_possible, to be set if fast frequency switching can be used for the given policy. Implement the ->fast_switch callback in the ACPI cpufreq driver and make it set fast_switch_possible during policy initialization as appropriate. Signed-off-by: Rafael J. Wysocki --- Changes from the previous version: - Drop a bogus check from cpufreq_driver_fast_switch(). --- drivers/cpufreq/acpi-cpufreq.c | 53 +++++++++++++++++++++++++++++++++++++++++ drivers/cpufreq/cpufreq.c | 30 +++++++++++++++++++++++ include/linux/cpufreq.h | 6 ++++ 3 files changed, 89 insertions(+) Index: linux-pm/drivers/cpufreq/acpi-cpufreq.c =================================================================== --- linux-pm.orig/drivers/cpufreq/acpi-cpufreq.c +++ linux-pm/drivers/cpufreq/acpi-cpufreq.c @@ -458,6 +458,55 @@ static int acpi_cpufreq_target(struct cp return result; } +unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + struct acpi_cpufreq_data *data = policy->driver_data; + struct acpi_processor_performance *perf; + struct cpufreq_frequency_table *entry, *found; + unsigned int next_perf_state, next_freq, freq; + + /* + * Find the closest frequency above target_freq or equal to it. + * + * The table is sorted in the reverse order with respect to the + * frequency and all of the entries are valid (see the initialization). + */ + entry = data->freq_table; + do { + entry++; + freq = entry->frequency; + } while (freq >= target_freq && freq != CPUFREQ_TABLE_END); + found = entry - 1; + /* + * Use the one found or the previous one, depending on the relation. + * CPUFREQ_RELATION_H is not taken into account here, but it is not + * expected to be passed to this function anyway. + */ + next_freq = found->frequency; + if (freq == CPUFREQ_TABLE_END || relation != CPUFREQ_RELATION_C || + target_freq - freq >= next_freq - target_freq) { + next_perf_state = found->driver_data; + } else { + next_freq = freq; + next_perf_state = entry->driver_data; + } + + perf = to_perf_data(data); + if (perf->state == next_perf_state) { + if (unlikely(data->resume)) + data->resume = 0; + else + return next_freq; + } + + data->cpu_freq_write(&perf->control_register, + perf->states[next_perf_state].control); + perf->state = next_perf_state; + return next_freq; +} + static unsigned long acpi_cpufreq_guess_freq(struct acpi_cpufreq_data *data, unsigned int cpu) { @@ -740,6 +789,9 @@ static int acpi_cpufreq_cpu_init(struct goto err_unreg; } + policy->fast_switch_possible = !acpi_pstate_strict && + !(policy_is_shared(policy) && policy->shared_type != CPUFREQ_SHARED_TYPE_ANY); + data->freq_table = kzalloc(sizeof(*data->freq_table) * (perf->state_count+1), GFP_KERNEL); if (!data->freq_table) { @@ -874,6 +926,7 @@ static struct freq_attr *acpi_cpufreq_at static struct cpufreq_driver acpi_cpufreq_driver = { .verify = cpufreq_generic_frequency_table_verify, .target_index = acpi_cpufreq_target, + .fast_switch = acpi_cpufreq_fast_switch, .bios_limit = acpi_processor_get_bios_limit, .init = acpi_cpufreq_cpu_init, .exit = acpi_cpufreq_cpu_exit, Index: linux-pm/drivers/cpufreq/cpufreq.c =================================================================== --- linux-pm.orig/drivers/cpufreq/cpufreq.c +++ linux-pm/drivers/cpufreq/cpufreq.c @@ -1719,6 +1719,36 @@ EXPORT_SYMBOL(cpufreq_unregister_notifie * GOVERNORS * *********************************************************************/ +/** + * cpufreq_driver_fast_switch - Carry out a fast CPU frequency switch. + * @policy: cpufreq policy to switch the frequency for. + * @target_freq: New frequency to set (may be approximate). + * @relation: Relation to use for frequency selection. + * + * Carry out a fast frequency switch from interrupt context. + * + * This function must not be called if policy->fast_switch_possible is unset. + * + * Governors calling this function must guarantee that it will never be invoked + * twice in parallel for the same policy and that it will never be called in + * parallel with either ->target() or ->target_index() for the same policy. + * + * If CPUFREQ_ENTRY_INVALID is returned by the driver's ->fast_switch() + * callback, the hardware configuration must be preserved. + */ +void cpufreq_driver_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq, unsigned int relation) +{ + unsigned int freq; + + freq = cpufreq_driver->fast_switch(policy, target_freq, relation); + if (freq != CPUFREQ_ENTRY_INVALID) { + policy->cur = freq; + trace_cpu_frequency(freq, smp_processor_id()); + } +} +EXPORT_SYMBOL_GPL(cpufreq_driver_fast_switch); + /* Must set freqs->new to intermediate frequency */ static int __target_intermediate(struct cpufreq_policy *policy, struct cpufreq_freqs *freqs, int index) Index: linux-pm/include/linux/cpufreq.h =================================================================== --- linux-pm.orig/include/linux/cpufreq.h +++ linux-pm/include/linux/cpufreq.h @@ -81,6 +81,7 @@ struct cpufreq_policy { struct cpufreq_governor *governor; /* see below */ void *governor_data; char last_governor[CPUFREQ_NAME_LEN]; /* last governor used */ + bool fast_switch_possible; struct work_struct update; /* if update_policy() needs to be * called, but you're in IRQ context */ @@ -236,6 +237,9 @@ struct cpufreq_driver { unsigned int relation); /* Deprecated */ int (*target_index)(struct cpufreq_policy *policy, unsigned int index); + unsigned int (*fast_switch)(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation); /* * Only for drivers with target_index() and CPUFREQ_ASYNC_NOTIFICATION * unset. @@ -450,6 +454,8 @@ struct cpufreq_governor { }; /* Pass a target to the cpufreq driver */ +void cpufreq_driver_fast_switch(struct cpufreq_policy *policy, + unsigned int target_freq, unsigned int relation); int cpufreq_driver_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation);