From 059835bbfa282918a1e8e5e2d9628aa600093052 Mon Sep 17 00:00:00 2001 From: Zuo An Date: Fri, 24 Oct 2025 05:46:47 +0000 Subject: [PATCH 1/7] tools/power/cpupower: Support building libcpupower statically The cpupower Makefile built and installed libcpupower as a shared library (libcpupower.so) without passing `STATIC=true`, but did not build a static version of the library even with `STATIC=true`. (Only the programs were static). Thus, out-of-tree programs using libcpupower were unable to link statically against the library without having access to intermediate object files produced during the build. This fixes that situation by ensuring that libcpupower.a is built and installed when `STATIC=true` is specified. Link: https://lore.kernel.org/r/x7geegquiks3zndiavw2arihdc2rk7e2dx3lk7yxkewqii6zpg@tzjijqxyzwmu Signed-off-by: Zuo An Signed-off-by: Shuah Khan --- tools/power/cpupower/Makefile | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/tools/power/cpupower/Makefile b/tools/power/cpupower/Makefile index c43db1c41205..a1df9196dc45 100644 --- a/tools/power/cpupower/Makefile +++ b/tools/power/cpupower/Makefile @@ -37,9 +37,7 @@ NLS ?= true # cpufreq-bench benchmarking tool CPUFREQ_BENCH ?= true -# Do not build libraries, but build the code in statically -# Libraries are still built, otherwise the Makefile code would -# be rather ugly. +# Build the code, including libraries, statically. export STATIC ?= false # Prefix to the directories we're installing to @@ -207,14 +205,25 @@ $(OUTPUT)lib/%.o: $(LIB_SRC) $(LIB_HEADERS) $(ECHO) " CC " $@ $(QUIET) $(CC) $(CFLAGS) -fPIC -o $@ -c lib/$*.c -$(OUTPUT)libcpupower.so.$(LIB_VER): $(LIB_OBJS) +ifeq ($(strip $(STATIC)),true) +LIBCPUPOWER := libcpupower.a +else +LIBCPUPOWER := libcpupower.so.$(LIB_VER) +endif + +$(OUTPUT)$(LIBCPUPOWER): $(LIB_OBJS) +ifeq ($(strip $(STATIC)),true) + $(ECHO) " AR " $@ + $(QUIET) $(AR) rcs $@ $(LIB_OBJS) +else $(ECHO) " LD " $@ $(QUIET) $(CC) -shared $(CFLAGS) $(LDFLAGS) -o $@ \ -Wl,-soname,libcpupower.so.$(LIB_MAJ) $(LIB_OBJS) @ln -sf $(@F) $(OUTPUT)libcpupower.so @ln -sf $(@F) $(OUTPUT)libcpupower.so.$(LIB_MAJ) +endif -libcpupower: $(OUTPUT)libcpupower.so.$(LIB_VER) +libcpupower: $(OUTPUT)$(LIBCPUPOWER) # Let all .o files depend on its .c file and all headers # Might be worth to put this into utils/Makefile at some point of time @@ -224,7 +233,7 @@ $(OUTPUT)%.o: %.c $(ECHO) " CC " $@ $(QUIET) $(CC) $(CFLAGS) -I./lib -I ./utils -o $@ -c $*.c -$(OUTPUT)cpupower: $(UTIL_OBJS) $(OUTPUT)libcpupower.so.$(LIB_VER) +$(OUTPUT)cpupower: $(UTIL_OBJS) $(OUTPUT)$(LIBCPUPOWER) $(ECHO) " CC " $@ ifeq ($(strip $(STATIC)),true) $(QUIET) $(CC) $(CFLAGS) $(LDFLAGS) $(UTIL_OBJS) -lrt -lpci -L$(OUTPUT) -o $@ @@ -269,7 +278,7 @@ update-po: $(OUTPUT)po/$(PACKAGE).pot done; endif -compile-bench: $(OUTPUT)libcpupower.so.$(LIB_VER) +compile-bench: $(OUTPUT)$(LIBCPUPOWER) @V=$(V) confdir=$(confdir) $(MAKE) -C bench O=$(OUTPUT) # we compile into subdirectories. if the target directory is not the @@ -287,6 +296,7 @@ clean: -find $(OUTPUT) \( -not -type d \) -and \( -name '*~' -o -name '*.[oas]' \) -type f -print \ | xargs rm -f -rm -f $(OUTPUT)cpupower + -rm -f $(OUTPUT)libcpupower.a -rm -f $(OUTPUT)libcpupower.so* -rm -rf $(OUTPUT)po/*.gmo -rm -rf $(OUTPUT)po/*.pot @@ -295,7 +305,11 @@ clean: install-lib: libcpupower $(INSTALL) -d $(DESTDIR)${libdir} +ifeq ($(strip $(STATIC)),true) + $(CP) $(OUTPUT)libcpupower.a $(DESTDIR)${libdir}/ +else $(CP) $(OUTPUT)libcpupower.so* $(DESTDIR)${libdir}/ +endif $(INSTALL) -d $(DESTDIR)${includedir} $(INSTALL_DATA) lib/cpufreq.h $(DESTDIR)${includedir}/cpufreq.h $(INSTALL_DATA) lib/cpuidle.h $(DESTDIR)${includedir}/cpuidle.h @@ -336,11 +350,7 @@ install-bench: compile-bench @#DESTDIR must be set from outside to survive @sbindir=$(sbindir) bindir=$(bindir) docdir=$(docdir) confdir=$(confdir) $(MAKE) -C bench O=$(OUTPUT) install -ifeq ($(strip $(STATIC)),true) -install: all install-tools install-man $(INSTALL_NLS) $(INSTALL_BENCH) -else install: all install-lib install-tools install-man $(INSTALL_NLS) $(INSTALL_BENCH) -endif uninstall: - rm -f $(DESTDIR)${libdir}/libcpupower.* From a4e6512a79d8486dccf3e8b066e5d6bd5ff95446 Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:42 +0100 Subject: [PATCH 2/7] PM: QoS: Introduce a CPU system wakeup QoS limit Some platforms supports multiple low power states for CPUs that can be used when entering system-wide suspend. Currently we are always selecting the deepest possible state for the CPUs, which can break the system wakeup latency constraint that may be required for a use case. Let's take the first step towards addressing this problem, by introducing an interface for user space, that allows us to specify the CPU system wakeup QoS limit. Subsequent changes will start taking into account the new QoS limit. Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-2-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- include/linux/pm_qos.h | 9 ++++ kernel/power/Kconfig | 11 +++++ kernel/power/qos.c | 106 +++++++++++++++++++++++++++++++++++++++++ 3 files changed, 126 insertions(+) diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h index 4a69d4af3ff8..6cea4455f867 100644 --- a/include/linux/pm_qos.h +++ b/include/linux/pm_qos.h @@ -162,6 +162,15 @@ static inline void cpu_latency_qos_update_request(struct pm_qos_request *req, static inline void cpu_latency_qos_remove_request(struct pm_qos_request *req) {} #endif +#ifdef CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP +s32 cpu_wakeup_latency_qos_limit(void); +#else +static inline s32 cpu_wakeup_latency_qos_limit(void) +{ + return PM_QOS_RESUME_LATENCY_NO_CONSTRAINT; +} +#endif + #ifdef CONFIG_PM enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask); enum pm_qos_flags_status dev_pm_qos_flags(struct device *dev, s32 mask); diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index 54a623680019..05337f437cca 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -202,6 +202,17 @@ config PM_WAKELOCKS_GC depends on PM_WAKELOCKS default y +config PM_QOS_CPU_SYSTEM_WAKEUP + bool "User space interface for CPU system wakeup QoS" + depends on CPU_IDLE + help + Enable this to allow user space via the cpu_wakeup_latency file to + specify a CPU system wakeup latency limit. + + This may be particularly useful for platforms supporting multiple low + power states for CPUs during system-wide suspend and s2idle in + particular. + config PM bool "Device power management core functionality" help diff --git a/kernel/power/qos.c b/kernel/power/qos.c index 4244b069442e..f7d8064e9adc 100644 --- a/kernel/power/qos.c +++ b/kernel/power/qos.c @@ -415,6 +415,105 @@ static struct miscdevice cpu_latency_qos_miscdev = { .fops = &cpu_latency_qos_fops, }; +#ifdef CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP +/* The CPU system wakeup latency QoS. */ +static struct pm_qos_constraints cpu_wakeup_latency_constraints = { + .list = PLIST_HEAD_INIT(cpu_wakeup_latency_constraints.list), + .target_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT, + .default_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT, + .no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT, + .type = PM_QOS_MIN, +}; + +/** + * cpu_wakeup_latency_qos_limit - Current CPU system wakeup latency QoS limit. + * + * Returns the current CPU system wakeup latency QoS limit that may have been + * requested by user space. + */ +s32 cpu_wakeup_latency_qos_limit(void) +{ + return pm_qos_read_value(&cpu_wakeup_latency_constraints); +} + +static int cpu_wakeup_latency_qos_open(struct inode *inode, struct file *filp) +{ + struct pm_qos_request *req; + + req = kzalloc(sizeof(*req), GFP_KERNEL); + if (!req) + return -ENOMEM; + + req->qos = &cpu_wakeup_latency_constraints; + pm_qos_update_target(req->qos, &req->node, PM_QOS_ADD_REQ, + PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); + filp->private_data = req; + + return 0; +} + +static int cpu_wakeup_latency_qos_release(struct inode *inode, + struct file *filp) +{ + struct pm_qos_request *req = filp->private_data; + + filp->private_data = NULL; + pm_qos_update_target(req->qos, &req->node, PM_QOS_REMOVE_REQ, + PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); + kfree(req); + + return 0; +} + +static ssize_t cpu_wakeup_latency_qos_read(struct file *filp, char __user *buf, + size_t count, loff_t *f_pos) +{ + s32 value = pm_qos_read_value(&cpu_wakeup_latency_constraints); + + return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32)); +} + +static ssize_t cpu_wakeup_latency_qos_write(struct file *filp, + const char __user *buf, + size_t count, loff_t *f_pos) +{ + struct pm_qos_request *req = filp->private_data; + s32 value; + + if (count == sizeof(s32)) { + if (copy_from_user(&value, buf, sizeof(s32))) + return -EFAULT; + } else { + int ret; + + ret = kstrtos32_from_user(buf, count, 16, &value); + if (ret) + return ret; + } + + if (value < 0) + return -EINVAL; + + pm_qos_update_target(req->qos, &req->node, PM_QOS_UPDATE_REQ, value); + + return count; +} + +static const struct file_operations cpu_wakeup_latency_qos_fops = { + .open = cpu_wakeup_latency_qos_open, + .release = cpu_wakeup_latency_qos_release, + .read = cpu_wakeup_latency_qos_read, + .write = cpu_wakeup_latency_qos_write, + .llseek = noop_llseek, +}; + +static struct miscdevice cpu_wakeup_latency_qos_miscdev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "cpu_wakeup_latency", + .fops = &cpu_wakeup_latency_qos_fops, +}; +#endif /* CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP */ + static int __init cpu_latency_qos_init(void) { int ret; @@ -424,6 +523,13 @@ static int __init cpu_latency_qos_init(void) pr_err("%s: %s setup failed\n", __func__, cpu_latency_qos_miscdev.name); +#ifdef CONFIG_PM_QOS_CPU_SYSTEM_WAKEUP + ret = misc_register(&cpu_wakeup_latency_qos_miscdev); + if (ret < 0) + pr_err("%s: %s setup failed\n", __func__, + cpu_wakeup_latency_qos_miscdev.name); +#endif + return ret; } late_initcall(cpu_latency_qos_init); From 8e7de6dc420979f4e4443807b71dcc8b72d8c4a9 Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:43 +0100 Subject: [PATCH 3/7] pmdomain: Respect the CPU system wakeup QoS limit for s2idle A CPU system wakeup QoS limit may have been requested by user space. To avoid breaking this constraint when entering a low power state during s2idle through genpd, let's extend the corresponding genpd governor for CPUs. More precisely, during s2idle let the genpd governor select a suitable domain idle state, by taking into account the QoS limit. Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-3-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- drivers/pmdomain/core.c | 10 ++++++++-- drivers/pmdomain/governor.c | 27 +++++++++++++++++++++++++++ include/linux/pm_domain.h | 1 + 3 files changed, 36 insertions(+), 2 deletions(-) diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c index 61c2277c9ce3..4fd546ef0448 100644 --- a/drivers/pmdomain/core.c +++ b/drivers/pmdomain/core.c @@ -1425,8 +1425,14 @@ static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock, return; } - /* Choose the deepest state when suspending */ - genpd->state_idx = genpd->state_count - 1; + if (genpd->gov && genpd->gov->system_power_down_ok) { + if (!genpd->gov->system_power_down_ok(&genpd->domain)) + return; + } else { + /* Default to the deepest state. */ + genpd->state_idx = genpd->state_count - 1; + } + if (_genpd_power_off(genpd, false)) { genpd->states[genpd->state_idx].rejected++; return; diff --git a/drivers/pmdomain/governor.c b/drivers/pmdomain/governor.c index 39359811a930..bd1b9d66d4a5 100644 --- a/drivers/pmdomain/governor.c +++ b/drivers/pmdomain/governor.c @@ -415,9 +415,36 @@ static bool cpu_power_down_ok(struct dev_pm_domain *pd) return false; } +static bool cpu_system_power_down_ok(struct dev_pm_domain *pd) +{ + s64 constraint_ns = cpu_wakeup_latency_qos_limit() * NSEC_PER_USEC; + struct generic_pm_domain *genpd = pd_to_genpd(pd); + int state_idx = genpd->state_count - 1; + + if (!(genpd->flags & GENPD_FLAG_CPU_DOMAIN)) { + genpd->state_idx = state_idx; + return true; + } + + /* Find the deepest state for the latency constraint. */ + while (state_idx >= 0) { + s64 latency_ns = genpd->states[state_idx].power_off_latency_ns + + genpd->states[state_idx].power_on_latency_ns; + + if (latency_ns <= constraint_ns) { + genpd->state_idx = state_idx; + return true; + } + state_idx--; + } + + return false; +} + struct dev_power_governor pm_domain_cpu_gov = { .suspend_ok = default_suspend_ok, .power_down_ok = cpu_power_down_ok, + .system_power_down_ok = cpu_system_power_down_ok, }; #endif diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h index f67a2cb7d781..93ba0143ca47 100644 --- a/include/linux/pm_domain.h +++ b/include/linux/pm_domain.h @@ -153,6 +153,7 @@ enum genpd_sync_state { }; struct dev_power_governor { + bool (*system_power_down_ok)(struct dev_pm_domain *domain); bool (*power_down_ok)(struct dev_pm_domain *domain); bool (*suspend_ok)(struct device *dev); }; From e2e4695f015eacbe11178540524438f631ba9413 Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:44 +0100 Subject: [PATCH 4/7] pmdomain: Respect the CPU system wakeup QoS limit for cpuidle The CPU system wakeup QoS limit must be respected for the regular cpuidle state selection. Therefore, let's extend the genpd governor for CPUs to take the constraint into account when it selects a domain idle state for the corresponding PM domain. Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-4-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- drivers/pmdomain/governor.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/pmdomain/governor.c b/drivers/pmdomain/governor.c index bd1b9d66d4a5..05e68680f34b 100644 --- a/drivers/pmdomain/governor.c +++ b/drivers/pmdomain/governor.c @@ -351,7 +351,7 @@ static bool cpu_power_down_ok(struct dev_pm_domain *pd) ktime_t domain_wakeup, next_hrtimer; ktime_t now = ktime_get(); struct device *cpu_dev; - s64 cpu_constraint, global_constraint; + s64 cpu_constraint, global_constraint, wakeup_constraint; s64 idle_duration_ns; int cpu, i; @@ -362,7 +362,11 @@ static bool cpu_power_down_ok(struct dev_pm_domain *pd) if (!(genpd->flags & GENPD_FLAG_CPU_DOMAIN)) return true; + wakeup_constraint = cpu_wakeup_latency_qos_limit(); global_constraint = cpu_latency_qos_limit(); + if (global_constraint > wakeup_constraint) + global_constraint = wakeup_constraint; + /* * Find the next wakeup for any of the online CPUs within the PM domain * and its subdomains. Note, we only need the genpd->cpus, as it already From 99b42445f4a4aaff75eca24dfc9e6e376292dd48 Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:45 +0100 Subject: [PATCH 5/7] sched: idle: Respect the CPU system wakeup QoS limit for s2idle A CPU system wakeup QoS limit may have been requested by user space. To avoid breaking this constraint when entering a low power state during s2idle, let's start to take into account the QoS limit. Acked-by: Peter Zijlstra (Intel) Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-5-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/cpuidle.c | 12 +++++++----- include/linux/cpuidle.h | 6 ++++-- kernel/sched/idle.c | 12 +++++++----- 3 files changed, 18 insertions(+), 12 deletions(-) diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 56132e843c99..c7876e9e024f 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -184,20 +184,22 @@ static noinstr void enter_s2idle_proper(struct cpuidle_driver *drv, * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle. * @drv: cpuidle driver for the given CPU. * @dev: cpuidle device for the given CPU. + * @latency_limit_ns: Idle state exit latency limit * * If there are states with the ->enter_s2idle callback, find the deepest of * them and enter it with frozen tick. */ -int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev) +int cpuidle_enter_s2idle(struct cpuidle_driver *drv, struct cpuidle_device *dev, + u64 latency_limit_ns) { int index; /* - * Find the deepest state with ->enter_s2idle present, which guarantees - * that interrupts won't be enabled when it exits and allows the tick to - * be frozen safely. + * Find the deepest state with ->enter_s2idle present that meets the + * specified latency limit, which guarantees that interrupts won't be + * enabled when it exits and allows the tick to be frozen safely. */ - index = find_deepest_state(drv, dev, U64_MAX, 0, true); + index = find_deepest_state(drv, dev, latency_limit_ns, 0, true); if (index > 0) { enter_s2idle_proper(drv, dev, index); local_irq_enable(); diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index a9ee4fe55dcf..4073690504a7 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -248,7 +248,8 @@ extern int cpuidle_find_deepest_state(struct cpuidle_driver *drv, struct cpuidle_device *dev, u64 latency_limit_ns); extern int cpuidle_enter_s2idle(struct cpuidle_driver *drv, - struct cpuidle_device *dev); + struct cpuidle_device *dev, + u64 latency_limit_ns); extern void cpuidle_use_deepest_state(u64 latency_limit_ns); #else static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv, @@ -256,7 +257,8 @@ static inline int cpuidle_find_deepest_state(struct cpuidle_driver *drv, u64 latency_limit_ns) {return -ENODEV; } static inline int cpuidle_enter_s2idle(struct cpuidle_driver *drv, - struct cpuidle_device *dev) + struct cpuidle_device *dev, + u64 latency_limit_ns) {return -ENODEV; } static inline void cpuidle_use_deepest_state(u64 latency_limit_ns) { diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index c39b089d4f09..c1c3d0166610 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -131,12 +131,13 @@ void __cpuidle default_idle_call(void) } static int call_cpuidle_s2idle(struct cpuidle_driver *drv, - struct cpuidle_device *dev) + struct cpuidle_device *dev, + u64 max_latency_ns) { if (current_clr_polling_and_test()) return -EBUSY; - return cpuidle_enter_s2idle(drv, dev); + return cpuidle_enter_s2idle(drv, dev, max_latency_ns); } static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev, @@ -205,12 +206,13 @@ static void cpuidle_idle_call(void) u64 max_latency_ns; if (idle_should_enter_s2idle()) { + max_latency_ns = cpu_wakeup_latency_qos_limit() * + NSEC_PER_USEC; - entered_state = call_cpuidle_s2idle(drv, dev); + entered_state = call_cpuidle_s2idle(drv, dev, + max_latency_ns); if (entered_state > 0) goto exit_idle; - - max_latency_ns = U64_MAX; } else { max_latency_ns = dev->forced_idle_latency_limit_ns; } From 2b8d594742398cdbf40012c0b3c8b71ca160e22d Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:46 +0100 Subject: [PATCH 6/7] cpuidle: Respect the CPU system wakeup QoS limit for cpuidle The CPU system wakeup QoS limit must be respected for the regular cpuidle state selection. Therefore, let's extend the common governor helper cpuidle_governor_latency_req(), to take the constraint into account. Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-6-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- drivers/cpuidle/governor.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/cpuidle/governor.c b/drivers/cpuidle/governor.c index 0d0f9751ff8f..5d0e7f78c6c5 100644 --- a/drivers/cpuidle/governor.c +++ b/drivers/cpuidle/governor.c @@ -111,6 +111,10 @@ s64 cpuidle_governor_latency_req(unsigned int cpu) struct device *device = get_cpu_device(cpu); int device_req = dev_pm_qos_raw_resume_latency(device); int global_req = cpu_latency_qos_limit(); + int global_wake_req = cpu_wakeup_latency_qos_limit(); + + if (global_req > global_wake_req) + global_req = global_wake_req; if (device_req > global_req) device_req = global_req; From c19dfb267c28032293515a635eaefbf9194629ac Mon Sep 17 00:00:00 2001 From: Ulf Hansson Date: Tue, 25 Nov 2025 12:26:47 +0100 Subject: [PATCH 7/7] Documentation: power/cpuidle: Document the CPU system wakeup latency QoS Let's document how the new CPU system wakeup latency QoS limit can be used from user space, along with how the constraint is taken into account for s2idle and cpuidle. Reviewed-by: Dhruva Gole Reviewed-by: Kevin Hilman (TI) Tested-by: Kevin Hilman (TI) Signed-off-by: Ulf Hansson Link: https://patch.msgid.link/20251125112650.329269-7-ulf.hansson@linaro.org Signed-off-by: Rafael J. Wysocki --- Documentation/admin-guide/pm/cpuidle.rst | 9 +++++++++ Documentation/power/pm_qos_interface.rst | 9 +++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/pm/cpuidle.rst b/Documentation/admin-guide/pm/cpuidle.rst index 0c090b076224..be4c1120e3f0 100644 --- a/Documentation/admin-guide/pm/cpuidle.rst +++ b/Documentation/admin-guide/pm/cpuidle.rst @@ -580,6 +580,15 @@ the given CPU as the upper limit for the exit latency of the idle states that they are allowed to select for that CPU. They should never select any idle states with exit latency beyond that limit. +While the above CPU QoS constraints apply to CPU idle time management, user +space may also request a CPU system wakeup latency QoS limit, via the +`cpu_wakeup_latency` file. This QoS constraint is respected when selecting a +suitable idle state for the CPUs, while entering the system-wide suspend-to-idle +sleep state, but also to the regular CPU idle time management. + +Note that, the management of the `cpu_wakeup_latency` file works according to +the 'cpu_dma_latency' file from user space point of view. Moreover, the unit +is also microseconds. Idle States Control Via Kernel Command Line =========================================== diff --git a/Documentation/power/pm_qos_interface.rst b/Documentation/power/pm_qos_interface.rst index 5019c79c7710..4c008e2202f0 100644 --- a/Documentation/power/pm_qos_interface.rst +++ b/Documentation/power/pm_qos_interface.rst @@ -55,7 +55,8 @@ int cpu_latency_qos_request_active(handle): From user space: -The infrastructure exposes one device node, /dev/cpu_dma_latency, for the CPU +The infrastructure exposes two separate device nodes, /dev/cpu_dma_latency for +the CPU latency QoS and /dev/cpu_wakeup_latency for the CPU system wakeup latency QoS. Only processes can register a PM QoS request. To provide for automatic @@ -63,15 +64,15 @@ cleanup of a process, the interface requires the process to register its parameter requests as follows. To register the default PM QoS target for the CPU latency QoS, the process must -open /dev/cpu_dma_latency. +open /dev/cpu_dma_latency. To register a CPU system wakeup QoS limit, the +process must open /dev/cpu_wakeup_latency. As long as the device node is held open that process has a registered request on the parameter. To change the requested target value, the process needs to write an s32 value to the open device node. Alternatively, it can write a hex string for the value -using the 10 char long format e.g. "0x12345678". This translates to a -cpu_latency_qos_update_request() call. +using the 10 char long format e.g. "0x12345678". To remove the user mode request for a target value simply close the device node.