On Friday, November 22, 2013 04:59:48 PM Viresh Kumar wrote:
This patch adds cpufreq callbacks to dpm_{suspend|resume}_noirq() for handling suspend/resume of cpufreq governors. This is required for early suspend and late resume of governors.
There are multiple problems that are fixed by this patch:
- Nishanth Menon (TI) found an interesting problem on his platform, OMAP. His board wasn't working well with suspend/resume as calls for removing non-boot CPUs was turning out into a call to drivers ->target() which then tries to play with regulators. But regulators and their I2C bus were already suspended and this resulted in a failure. This is why we need a PM notifier here.
- Lan Tianyu (Intel) & Jinhyuk Choi (Broadcom) found another issue where tunables configuration for clusters/sockets with non-boot CPUs was getting lost after suspend/resume, as we were notifying governors with CPUFREQ_GOV_POLICY_EXIT on removal of the last cpu for that policy and so deallocating memory for tunables.
Reported-by: Lan Tianyu tianyu.lan@intel.com Reported-by: Nishanth Menon nm@ti.com Reported-by: Jinhyuk Choi jinchoi@broadcom.com Signed-off-by: Viresh Kumar viresh.kumar@linaro.org
drivers/base/power/main.c | 3 +++ drivers/cpufreq/cpufreq.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/cpufreq.h | 3 +++ 3 files changed, 68 insertions(+)
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index c12e9b9..0fbe792 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -29,6 +29,7 @@ #include <linux/async.h> #include <linux/suspend.h> #include <trace/events/power.h> +#include <linux/cpufreq.h> #include <linux/cpuidle.h> #include <linux/timer.h> @@ -540,6 +541,7 @@ static void dpm_resume_noirq(pm_message_t state) dpm_show_time(starttime, state, "noirq"); resume_device_irqs(); cpuidle_resume();
- cpufreq_resume();
} /** @@ -955,6 +957,7 @@ static int dpm_suspend_noirq(pm_message_t state) ktime_t starttime = ktime_get(); int error = 0;
- cpufreq_suspend(); cpuidle_pause(); suspend_device_irqs(); mutex_lock(&dpm_list_mtx);
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 02d534d..540bd87 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -26,6 +26,7 @@ #include <linux/module.h> #include <linux/mutex.h> #include <linux/slab.h> +#include <linux/suspend.h> #include <linux/syscore_ops.h> #include <linux/tick.h> #include <trace/events/power.h> @@ -47,6 +48,9 @@ static LIST_HEAD(cpufreq_policy_list); static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor); #endif +/* Flag to suspend/resume CPUFreq governors */ +static bool cpufreq_suspended;
static inline bool has_target(void) { return cpufreq_driver->target_index || cpufreq_driver->target; @@ -1462,6 +1466,54 @@ static struct subsys_interface cpufreq_interface = { .remove_dev = cpufreq_remove_dev, }; +/*
- Callbacks for suspending/resuming governors as some platforms can't change
- frequency after this point in suspend cycle. Because some of the devices
- (like: i2c, regulators, etc) they use for changing frequency are suspended
- quickly after this point.
- */
+void cpufreq_suspend(void) +{
- struct cpufreq_policy *policy;
- unsigned long flags;
- if (!has_target())
return;- pr_debug("%s: Suspending Governors\n", __func__);
- list_for_each_entry(policy, &cpufreq_policy_list, policy_list)
if (__cpufreq_governor(policy, CPUFREQ_GOV_STOP))pr_err("%s: Failed to stop governor for policy: %p\n",__func__, policy);- write_lock_irqsave(&cpufreq_driver_lock, flags);
- cpufreq_suspended = true;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
The locking here is pointless. It doesn't prevent any race conditions from happening.
+}
+void cpufreq_resume(void) +{
- struct cpufreq_policy *policy;
- unsigned long flags;
- if (!has_target())
return;- pr_debug("%s: Resuming Governors\n", __func__);
- write_lock_irqsave(&cpufreq_driver_lock, flags);
- cpufreq_suspended = false;
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
Same here.
- list_for_each_entry(policy, &cpufreq_policy_list, policy_list)
if (__cpufreq_governor(policy, CPUFREQ_GOV_START) ||__cpufreq_governor(policy,CPUFREQ_GOV_LIMITS))pr_err("%s: Failed to start governor for policy: %p\n",__func__, policy);+}
/**
- cpufreq_bp_suspend - Prepare the boot CPU for system suspend.
@@ -1752,6 +1804,8 @@ EXPORT_SYMBOL_GPL(cpufreq_driver_target); static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event) {
- unsigned long flags;
- bool is_suspended; int ret;
/* Only must be defined when default governor is known to have latency @@ -1764,6 +1818,14 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, struct cpufreq_governor *gov = NULL; #endif
- /* Don't start any governor operations if we are entering suspend */
- read_lock_irqsave(&cpufreq_driver_lock, flags);
- is_suspended = cpufreq_suspended;
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
And same here.
- if (is_suspended)
And you can check cpufreq_suspended directly here.
return 0;- if (policy->governor->max_transition_latency && policy->cpuinfo.transition_latency > policy->governor->max_transition_latency) {
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index dc196bb..6d93f91 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -255,6 +255,9 @@ struct cpufreq_driver { int cpufreq_register_driver(struct cpufreq_driver *driver_data); int cpufreq_unregister_driver(struct cpufreq_driver *driver_data); +void cpufreq_suspend(void); +void cpufreq_resume(void);
const char *cpufreq_get_current_driver(void); static inline void cpufreq_verify_within_limits(struct cpufreq_policy *policy,
Thanks!