From 67e3242ee28052daa90e1fa193efc601939fde58 Mon Sep 17 00:00:00 2001 From: Lina Iyer Date: Wed, 20 Jan 2021 08:50:41 -0700 Subject: PM: domains: inform PM domain of a device's next wakeup Some devices may have a predictable interrupt pattern while executing usecases. An example would be the VSYNC interrupt associated with display devices. A 60 Hz display could cause a interrupt every 16 ms. If the device were in a PM domain, the domain would need to be powered up for device to resume and handle the interrupt. Entering a domain idle state saves power, only if the residency of the idle state is met. Without knowing the idle duration of the domain, the governor would just choose the deepest idle state that matches the QoS requirements. The domain might be powered off just as the device is expecting to wake up. If devices could inform PM frameworks of their next event, the parent PM domain's idle duration can be determined. So let's add the dev_pm_genpd_set_next_wakeup() API for the device to inform PM domains of the impending wakeup. This information will be the domain governor to determine the best idle state given the wakeup. Signed-off-by: Lina Iyer Reviewed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki --- include/linux/pm_domain.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index 2ca919ae8d36..735583c0bc6d 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h @@ -9,6 +9,7 @@ #define _LINUX_PM_DOMAIN_H #include +#include #include #include #include @@ -191,6 +192,7 @@ struct generic_pm_domain_data { struct notifier_block *power_nb; int cpu; unsigned int performance_state; + ktime_t next_wakeup; void *data; }; @@ -217,6 +219,7 @@ int pm_genpd_remove(struct generic_pm_domain *genpd); int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state); int dev_pm_genpd_add_notifier(struct device *dev, struct notifier_block *nb); int dev_pm_genpd_remove_notifier(struct device *dev); +void dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next); extern struct dev_power_governor simple_qos_governor; extern struct dev_power_governor pm_domain_always_on_gov; @@ -275,6 +278,9 @@ static inline int dev_pm_genpd_remove_notifier(struct device *dev) return -EOPNOTSUPP; } +static inline void dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next) +{ } + #define simple_qos_governor (*(struct dev_power_governor *)(NULL)) #define pm_domain_always_on_gov (*(struct dev_power_governor *)(NULL)) #endif -- cgit v1.2.3 From c79aa080fb0f60a0e24c87014dc9c2f373e1379b Mon Sep 17 00:00:00 2001 From: Lina Iyer Date: Wed, 20 Jan 2021 08:50:42 -0700 Subject: PM: domains: use device's next wakeup to determine domain idle state Currently, a PM domain's idle state is determined based on whether the QoS requirements are met. However, even entering an idle state may waste power if the minimum residency requirements aren't fulfilled. CPU PM domains use the next timer wakeup for the CPUs in the domain to determine the sleep duration of the domain. This is compared with the idle state residencies to determine the optimal idle state. For other PM domains, determining the sleep length is not that straight forward. But if the device's next_event is available, we can use that to determine the sleep duration of the PM domain. Let's update the domain governor logic to check for idle state residency based on the next wakeup of devices as well as QoS constraints. But since, not all domains may contain devices capable of specifying the next wakeup, let's enable this additional check only if specified by the domain's flags when initializing the domain. Signed-off-by: Lina Iyer Reviewed-by: Ulf Hansson Signed-off-by: Rafael J. Wysocki --- include/linux/pm_domain.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index 735583c0bc6d..dfcfbcecc34b 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h @@ -56,6 +56,10 @@ * * GENPD_FLAG_RPM_ALWAYS_ON: Instructs genpd to always keep the PM domain * powered on except for system suspend. + * + * GENPD_FLAG_MIN_RESIDENCY: Enable the genpd governor to consider its + * components' next wakeup when determining the + * optimal idle state. */ #define GENPD_FLAG_PM_CLK (1U << 0) #define GENPD_FLAG_IRQ_SAFE (1U << 1) @@ -63,6 +67,7 @@ #define GENPD_FLAG_ACTIVE_WAKEUP (1U << 3) #define GENPD_FLAG_CPU_DOMAIN (1U << 4) #define GENPD_FLAG_RPM_ALWAYS_ON (1U << 5) +#define GENPD_FLAG_MIN_RESIDENCY (1U << 6) enum gpd_status { GENPD_STATE_ON = 0, /* PM domain is on */ @@ -130,6 +135,7 @@ struct generic_pm_domain { unsigned int state); struct gpd_dev_ops dev_ops; s64 max_off_time_ns; /* Maximum allowed "suspended" time. */ + ktime_t next_wakeup; /* Maintained by the domain governor */ bool max_off_time_changed; bool cached_power_down_ok; bool cached_power_down_state_idx; -- cgit v1.2.3 From 0bfa0820c274b019583b3454c6c889c99c24558d Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Mon, 25 Jan 2021 14:29:18 -0500 Subject: PM: clk: make PM clock layer compatible with clocks that must sleep The clock API splits its interface into sleepable ant atomic contexts: - clk_prepare/clk_unprepare for stuff that might sleep - clk_enable_clk_disable for anything that may be done in atomic context The code handling runtime PM for clocks only calls clk_disable() on suspend requests, and clk_enable on resume requests. This means that runtime PM with clock providers that only have the prepare/unprepare methods implemented is basically useless. Many clock implementations can't accommodate atomic contexts. This is often the case when communication with the clock happens through another subsystem like I2C or SCMI. Let's make the clock PM code useful with such clocks by safely invoking clk_prepare/clk_unprepare upon resume/suspend requests. Of course, when such clocks are registered with the PM layer then pm_runtime_irq_safe() can't be used, and neither pm_runtime_suspend() nor pm_runtime_resume() may be invoked in atomic context. For clocks that do implement the enable and disable methods then everything just works as before. A note on sparse: According to https://lwn.net/Articles/109066/ there are things that sparse can't cope with. In particular, pm_clk_op_lock() and pm_clk_op_unlock() may or may not lock/unlock psd->lock depending on some runtime condition. To work around that we tell it the lock is always untaken for the purpose of static analisys. Thanks to Naresh Kamboju for reporting issues with the initial patch. Signed-off-by: Nicolas Pitre Tested-by: Naresh Kamboju Signed-off-by: Rafael J. Wysocki --- include/linux/clk.h | 24 +++++++++++++++++++++++- include/linux/pm.h | 2 ++ 2 files changed, 25 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/clk.h b/include/linux/clk.h index 31ff1bf1b79f..a4a86aa8b11a 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -238,6 +238,7 @@ static inline bool clk_is_match(const struct clk *p, const struct clk *q) #endif +#ifdef CONFIG_HAVE_CLK_PREPARE /** * clk_prepare - prepare a clock source * @clk: clock source @@ -246,10 +247,26 @@ static inline bool clk_is_match(const struct clk *p, const struct clk *q) * * Must not be called from within atomic context. */ -#ifdef CONFIG_HAVE_CLK_PREPARE int clk_prepare(struct clk *clk); int __must_check clk_bulk_prepare(int num_clks, const struct clk_bulk_data *clks); + +/** + * clk_is_enabled_when_prepared - indicate if preparing a clock also enables it. + * @clk: clock source + * + * Returns true if clk_prepare() implicitly enables the clock, effectively + * making clk_enable()/clk_disable() no-ops, false otherwise. + * + * This is of interest mainly to the power management code where actually + * disabling the clock also requires unpreparing it to have any material + * effect. + * + * Regardless of the value returned here, the caller must always invoke + * clk_enable() or clk_prepare_enable() and counterparts for usage counts + * to be right. + */ +bool clk_is_enabled_when_prepared(struct clk *clk); #else static inline int clk_prepare(struct clk *clk) { @@ -263,6 +280,11 @@ clk_bulk_prepare(int num_clks, const struct clk_bulk_data *clks) might_sleep(); return 0; } + +static inline bool clk_is_enabled_when_prepared(struct clk *clk) +{ + return false; +} #endif /** diff --git a/include/linux/pm.h b/include/linux/pm.h index 47aca6bac1d6..482313a8ccfc 100644 --- a/include/linux/pm.h +++ b/include/linux/pm.h @@ -537,6 +537,8 @@ struct pm_subsys_data { spinlock_t lock; unsigned int refcount; #ifdef CONFIG_PM_CLK + unsigned int clock_op_might_sleep; + struct mutex clock_mutex; struct list_head clock_list; #endif #ifdef CONFIG_PM_GENERIC_DOMAINS -- cgit v1.2.3