From 13ebeef6a1b9c4e5c9789f835cc4ec34873f0bb1 Mon Sep 17 00:00:00 2001 From: Huisong Li Date: Tue, 23 Dec 2025 18:09:09 +0800 Subject: ACPI: processor: idle: Optimize ACPI idle driver registration Currently, the ACPI idle driver is registered from within a CPU hotplug callback. Although this didn't cause any functional issues, this is questionable and confusing. And it is better to register the cpuidle driver when all of the CPUs have been brought up. So add a new function to initialize acpi_idle_driver based on the power management information of an available CPU and register cpuidle driver in acpi_processor_driver_init(). This commit has four changes under the commit 7a8c994cbb2d (ACPI: processor: idle: Optimize ACPI idle driver registration): 1) move acpi_processor_register_idle_driver() ahead of the driver_register(). 2) add acpi_processor_cstate_first_run_checks() before calling acpi_processor_get_power_info(). 3) squash the commit 9d68320b2bca (ACPI: processor: idle: Fix function defined but not used warning) into this change. 4) use for_each_possible_cpu(cpu) to scan all possible cpus. Signed-off-by: Huisong Li Tested-by: Borislav Petkov (AMD) [ rjw: New comment edits, changelog tweak ] Link: https://patch.msgid.link/20251223100914.2407069-2-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki --- include/acpi/processor.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/acpi/processor.h b/include/acpi/processor.h index d0eccbd920e5..ff864c1cee3a 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -423,6 +423,8 @@ int acpi_processor_power_init(struct acpi_processor *pr); int acpi_processor_power_exit(struct acpi_processor *pr); int acpi_processor_power_state_has_changed(struct acpi_processor *pr); int acpi_processor_hotplug(struct acpi_processor *pr); +void acpi_processor_register_idle_driver(void); +void acpi_processor_unregister_idle_driver(void); #else static inline int acpi_processor_power_init(struct acpi_processor *pr) { -- cgit v1.2.3 From 8ada9e11b3fc5d9e21c3a45c6c136944f7b28a14 Mon Sep 17 00:00:00 2001 From: Huisong Li Date: Tue, 23 Dec 2025 18:09:10 +0800 Subject: ACPI: processor: Remove unused empty stubs of some functions Empty stubs are defined in processor.h for some functions provided by the ACPI processor idle driver, but those functions are only used in the main ACPI processor driver which requires the ACPI processor idle driver to be present (selecting CONFIG_ACPI_PROCESSOR causes CONFIG_ACPI_PROCESSOR_IDLE to be selected too automatically). This means that the empty stubs in question are not really necessary and if both CONFIG_ACPI_PROCESSOR and CONFIG_ACPI_PROCESSOR_IDLE are unset, the compiler complains that they are defined, but not used. Drop them to get rid of the compiler warning. Signed-off-by: Huisong Li Tested-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251223100914.2407069-3-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki --- include/acpi/processor.h | 20 -------------------- 1 file changed, 20 deletions(-) (limited to 'include') diff --git a/include/acpi/processor.h b/include/acpi/processor.h index ff864c1cee3a..2976a6d0c54f 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -425,26 +425,6 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr); int acpi_processor_hotplug(struct acpi_processor *pr); void acpi_processor_register_idle_driver(void); void acpi_processor_unregister_idle_driver(void); -#else -static inline int acpi_processor_power_init(struct acpi_processor *pr) -{ - return -ENODEV; -} - -static inline int acpi_processor_power_exit(struct acpi_processor *pr) -{ - return -ENODEV; -} - -static inline int acpi_processor_power_state_has_changed(struct acpi_processor *pr) -{ - return -ENODEV; -} - -static inline int acpi_processor_hotplug(struct acpi_processor *pr) -{ - return -ENODEV; -} #endif /* CONFIG_ACPI_PROCESSOR_IDLE */ /* in processor_thermal.c */ -- cgit v1.2.3 From 31612f3642b1ec813c9c5915b4704e669630db28 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Tue, 23 Dec 2025 18:09:12 +0800 Subject: ACPI: processor: idle: Redefine two functions as void Notice that acpi_processor_power_init() and acpi_processor_power_exit() don't need to return any values because their callers don't check them anyway, so redefine those functions as void. While at it, rearrange the code in acpi_processor_power_init() to reduce the indentation level, get rid of a redundant local variable in that function, and rephrase a code comment in it. No intentional functional impact. Signed-off-by: Rafael J. Wysocki Reviewed-by: Mario Limonciello (AMD) Tested-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251223100914.2407069-5-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki --- drivers/acpi/processor_idle.c | 41 +++++++++++++++++++---------------------- include/acpi/processor.h | 4 ++-- 2 files changed, 21 insertions(+), 24 deletions(-) (limited to 'include') diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 0816356edb32..8704bc7ad91d 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -1391,47 +1391,45 @@ void acpi_processor_unregister_idle_driver(void) cpuidle_unregister_driver(&acpi_idle_driver); } -int acpi_processor_power_init(struct acpi_processor *pr) +void acpi_processor_power_init(struct acpi_processor *pr) { - int retval; struct cpuidle_device *dev; if (disabled_by_idle_boot_param()) - return 0; + return; acpi_processor_cstate_first_run_checks(); if (!acpi_processor_get_power_info(pr)) pr->flags.power_setup_done = 1; - if (pr->flags.power) { - dev = kzalloc(sizeof(*dev), GFP_KERNEL); - if (!dev) - return -ENOMEM; - per_cpu(acpi_cpuidle_device, pr->id) = dev; + if (!pr->flags.power) + return; - acpi_processor_setup_cpuidle_dev(pr, dev); + dev = kzalloc(sizeof(*dev), GFP_KERNEL); + if (!dev) + return; - /* Register per-cpu cpuidle_device. Cpuidle driver - * must already be registered before registering device - */ - retval = cpuidle_register_device(dev); - if (retval) { + per_cpu(acpi_cpuidle_device, pr->id) = dev; - per_cpu(acpi_cpuidle_device, pr->id) = NULL; - kfree(dev); - return retval; - } + acpi_processor_setup_cpuidle_dev(pr, dev); + + /* + * Register a cpuidle device for this CPU. The cpuidle driver using + * this device is expected to be registered. + */ + if (cpuidle_register_device(dev)) { + per_cpu(acpi_cpuidle_device, pr->id) = NULL; + kfree(dev); } - return 0; } -int acpi_processor_power_exit(struct acpi_processor *pr) +void acpi_processor_power_exit(struct acpi_processor *pr) { struct cpuidle_device *dev = per_cpu(acpi_cpuidle_device, pr->id); if (disabled_by_idle_boot_param()) - return 0; + return; if (pr->flags.power) { cpuidle_unregister_device(dev); @@ -1439,7 +1437,6 @@ int acpi_processor_power_exit(struct acpi_processor *pr) } pr->flags.power_setup_done = 0; - return 0; } MODULE_IMPORT_NS("ACPI_PROCESSOR_IDLE"); diff --git a/include/acpi/processor.h b/include/acpi/processor.h index 2976a6d0c54f..0200aef6e754 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -419,8 +419,8 @@ static inline void acpi_processor_throttling_init(void) {} /* in processor_idle.c */ extern struct cpuidle_driver acpi_idle_driver; #ifdef CONFIG_ACPI_PROCESSOR_IDLE -int acpi_processor_power_init(struct acpi_processor *pr); -int acpi_processor_power_exit(struct acpi_processor *pr); +void acpi_processor_power_init(struct acpi_processor *pr); +void acpi_processor_power_exit(struct acpi_processor *pr); int acpi_processor_power_state_has_changed(struct acpi_processor *pr); int acpi_processor_hotplug(struct acpi_processor *pr); void acpi_processor_register_idle_driver(void); -- cgit v1.2.3 From d8e43c89cf08ffea4825a24fb8dfd8bde4de9bb1 Mon Sep 17 00:00:00 2001 From: Huisong Li Date: Tue, 23 Dec 2025 18:09:13 +0800 Subject: ACPI: processor: idle: Rearrange declarations in header file Group all of the declarations of functions that belong to the ACPI processor idle driver together in one place in processor.h. While at it, drop the unnecessary extern modifier from the declaraions of two functions. Signed-off-by: Huisong Li Tested-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251223100914.2407069-6-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki --- include/acpi/processor.h | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'include') diff --git a/include/acpi/processor.h b/include/acpi/processor.h index 0200aef6e754..24fdaa3c2899 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -425,6 +425,8 @@ int acpi_processor_power_state_has_changed(struct acpi_processor *pr); int acpi_processor_hotplug(struct acpi_processor *pr); void acpi_processor_register_idle_driver(void); void acpi_processor_unregister_idle_driver(void); +int acpi_processor_ffh_lpi_probe(unsigned int cpu); +int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi); #endif /* CONFIG_ACPI_PROCESSOR_IDLE */ /* in processor_thermal.c */ @@ -447,11 +449,6 @@ static inline void acpi_thermal_cpufreq_exit(struct cpufreq_policy *policy) } #endif /* CONFIG_CPU_FREQ */ -#ifdef CONFIG_ACPI_PROCESSOR_IDLE -extern int acpi_processor_ffh_lpi_probe(unsigned int cpu); -extern int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi); -#endif - void acpi_processor_init_invariance_cppc(void); #endif -- cgit v1.2.3 From 24b09e849139f92bce0bb966f21409c95c60564a Mon Sep 17 00:00:00 2001 From: Huisong Li Date: Tue, 23 Dec 2025 18:09:14 +0800 Subject: ACPI: processor: Do not expose global variable acpi_idle_driver Move the cpuidle driver check from __acpi_processor_start() to acpi_processor_power_init() which allows variable acpi_idle_driver to become static. No intentional functional impact. Signed-off-by: Huisong Li Tested-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20251223100914.2407069-7-lihuisong@huawei.com Signed-off-by: Rafael J. Wysocki --- drivers/acpi/processor_driver.c | 3 +-- drivers/acpi/processor_idle.c | 9 ++++++++- include/acpi/processor.h | 1 - 3 files changed, 9 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c index f5b4f6a29143..882709796b4f 100644 --- a/drivers/acpi/processor_driver.c +++ b/drivers/acpi/processor_driver.c @@ -166,8 +166,7 @@ static int __acpi_processor_start(struct acpi_device *device) if (result && !IS_ENABLED(CONFIG_ACPI_CPU_FREQ_PSS)) dev_dbg(&device->dev, "CPPC data invalid or not present\n"); - if (cpuidle_get_driver() == &acpi_idle_driver) - acpi_processor_power_init(pr); + acpi_processor_power_init(pr); acpi_pss_perf_init(pr); diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 8704bc7ad91d..4ba45440d4c4 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -51,7 +51,7 @@ module_param(latency_factor, uint, 0644); static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device); -struct cpuidle_driver acpi_idle_driver = { +static struct cpuidle_driver acpi_idle_driver = { .name = "acpi_idle", .owner = THIS_MODULE, }; @@ -1395,6 +1395,13 @@ void acpi_processor_power_init(struct acpi_processor *pr) { struct cpuidle_device *dev; + /* + * The code below only works if the current cpuidle driver is the ACPI + * idle driver. + */ + if (cpuidle_get_driver() != &acpi_idle_driver) + return; + if (disabled_by_idle_boot_param()) return; diff --git a/include/acpi/processor.h b/include/acpi/processor.h index 24fdaa3c2899..7146a8e9e9c2 100644 --- a/include/acpi/processor.h +++ b/include/acpi/processor.h @@ -417,7 +417,6 @@ static inline void acpi_processor_throttling_init(void) {} #endif /* CONFIG_ACPI_CPU_FREQ_PSS */ /* in processor_idle.c */ -extern struct cpuidle_driver acpi_idle_driver; #ifdef CONFIG_ACPI_PROCESSOR_IDLE void acpi_processor_power_init(struct acpi_processor *pr); void acpi_processor_power_exit(struct acpi_processor *pr); -- cgit v1.2.3