From 499b3a512e1493ebdd056c92c24ac06c1010de88 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 12 Feb 2019 12:36:46 +0530 Subject: [PATCH] cpufreq: Allow light-weight tear down and bring up of CPUs The cpufreq core doesn't remove the cpufreq policy anymore on CPU offline operation, rather that happens when the CPU device gets unregistered from the kernel. This allows faster recovery when the CPU comes back online. This is also very useful during system wide suspend/resume where we offline all non-boot CPUs during suspend and then bring them back on resume. This commit takes the same idea a step ahead to allow drivers to do light weight tear-down and bring-up during CPU offline and online operations. A new set of callbacks is introduced, online/offline(). online() gets called when the first CPU of an inactive policy is brought up and offline() gets called when all the CPUs of a policy are offlined. The existing init/exit() callback get called on policy creation/destruction. They also get called instead of online/offline() callbacks if the online/offline() callbacks aren't provided. This also moves around some code to get executed only for the new-policy case going forward. Signed-off-by: Viresh Kumar [pending patch for mainline] Signed-off-by: Marek Szyprowski Change-Id: I27bd475cac802ffae345308fc145490966eda456 --- drivers/cpufreq/cpufreq.c | 49 +++++++++++++++++++++++++++++++---------------- include/linux/cpufreq.h | 2 ++ 2 files changed, 35 insertions(+), 16 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 9375430..6f34365 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1198,24 +1198,35 @@ static int cpufreq_online(unsigned int cpu) return -ENOMEM; } - cpumask_copy(policy->cpus, cpumask_of(cpu)); + if (!new_policy && cpufreq_driver->online) { + ret = cpufreq_driver->online(policy); + if (ret) { + pr_debug("%s: %d: initialization failed\n", __func__, + __LINE__); + goto out_exit_policy; + } - /* call driver. From then on the cpufreq must be able - * to accept all calls to ->verify and ->setpolicy for this CPU - */ - ret = cpufreq_driver->init(policy); - if (ret) { - pr_debug("initialization failed\n"); - goto out_free_policy; - } + /* Recover policy->cpus using related_cpus */ + cpumask_copy(policy->cpus, policy->related_cpus); + } else { + cpumask_copy(policy->cpus, cpumask_of(cpu)); - down_write(&policy->rwsem); + /* + * Call driver. From then on the cpufreq must be able + * to accept all calls to ->verify and ->setpolicy for this CPU. + */ + ret = cpufreq_driver->init(policy); + if (ret) { + pr_debug("%s: %d: initialization failed\n", __func__, + __LINE__); + goto out_free_policy; + } - if (new_policy) { /* related_cpus should at least include policy->cpus. */ cpumask_copy(policy->related_cpus, policy->cpus); } + down_write(&policy->rwsem); /* * affected cpus must always be the one, which are online. We aren't * managing offline cpus here. @@ -1405,11 +1416,12 @@ static int cpufreq_offline(unsigned int cpu) cpufreq_exit_governor(policy); /* - * Perform the ->exit() even during light-weight tear-down, - * since this is a core component, and is essential for the - * subsequent light-weight ->init() to succeed. + * Perform the ->offline() during light-weight tear-down, as + * that allows fast recovery when the CPU comes back. */ - if (cpufreq_driver->exit) { + if (cpufreq_driver->offline) { + cpufreq_driver->offline(policy); + } else if (cpufreq_driver->exit) { cpufreq_driver->exit(policy); policy->freq_table = NULL; } @@ -1438,8 +1450,13 @@ static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) cpumask_clear_cpu(cpu, policy->real_cpus); remove_cpu_dev_symlink(policy, dev); - if (cpumask_empty(policy->real_cpus)) + if (cpumask_empty(policy->real_cpus)) { + /* We did light-weight exit earlier, do full tear down now */ + if (cpufreq_driver->offline) + cpufreq_driver->exit(policy); + cpufreq_policy_free(policy); + } } /** diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index cbf85c4..2682c20 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -330,6 +330,8 @@ struct cpufreq_driver { /* optional */ int (*bios_limit)(int cpu, unsigned int *limit); + int (*online)(struct cpufreq_policy *policy); + int (*offline)(struct cpufreq_policy *policy); int (*exit)(struct cpufreq_policy *policy); void (*stop_cpu)(struct cpufreq_policy *policy); int (*suspend)(struct cpufreq_policy *policy); -- 2.7.4