Merge branches 'powercap' and 'pm-misc'

* powercap:
  powercap: intel_rapl: Use topology interface in rapl_init_domains()
  powercap: intel_rapl: Use topology interface in rapl_add_package()
  powercap/intel_rapl: add support for AlderLake Mobile
  powercap/drivers/dtpm: Fix size of object being allocated
  powercap/drivers/dtpm: Fix an IS_ERR() vs NULL check
  powercap/drivers/dtpm: Fix some missing unlock bugs
  powercap/drivers/dtpm: Fix a double shift bug
  powercap/drivers/dtpm: Fix __udivdi3 and __aeabi_uldivmod unresolved symbols
  powercap/drivers/dtpm: Add CPU energy model based support
  powercap/drivers/dtpm: Add API for dynamic thermal power management
  Documentation/powercap/dtpm: Add documentation for dtpm
  units: Add Watt units

* pm-misc:
  PM: Kconfig: remove unneeded "default n" options
  PM: EM: update Kconfig description and drop "default n" option

Documentation/power/index.rst

@@ -30,6 +30,7 @@ Power Management
     userland-swsusp
 
     powercap/powercap
+    powercap/dtpm
 
     regulator/consumer
     regulator/design

Documentation/power/powercap/dtpm.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+==========================================
+Dynamic Thermal Power Management framework
+==========================================
+
+On the embedded world, the complexity of the SoC leads to an
+increasing number of hotspots which need to be monitored and mitigated
+as a whole in order to prevent the temperature to go above the
+normative and legally stated 'skin temperature'.
+
+Another aspect is to sustain the performance for a given power budget,
+for example virtual reality where the user can feel dizziness if the
+performance is capped while a big CPU is processing something else. Or
+reduce the battery charging because the dissipated power is too high
+compared with the power consumed by other devices.
+
+The user space is the most adequate place to dynamically act on the
+different devices by limiting their power given an application
+profile: it has the knowledge of the platform.
+
+The Dynamic Thermal Power Management (DTPM) is a technique acting on
+the device power by limiting and/or balancing a power budget among
+different devices.
+
+The DTPM framework provides an unified interface to act on the
+device power.
+
+Overview
+========
+
+The DTPM framework relies on the powercap framework to create the
+powercap entries in the sysfs directory and implement the backend
+driver to do the connection with the power manageable device.
+
+The DTPM is a tree representation describing the power constraints
+shared between devices, not their physical positions.
+
+The nodes of the tree are a virtual description aggregating the power
+characteristics of the children nodes and their power limitations.
+
+The leaves of the tree are the real power manageable devices.
+
+For instance::
+
+  SoC
+   |
+   `-- pkg
+	|
+	|-- pd0 (cpu0-3)
+	|
+	`-- pd1 (cpu4-5)
+
+The pkg power will be the sum of pd0 and pd1 power numbers::
+
+  SoC (400mW - 3100mW)
+   |
+   `-- pkg (400mW - 3100mW)
+	|
+	|-- pd0 (100mW - 700mW)
+	|
+	`-- pd1 (300mW - 2400mW)
+
+When the nodes are inserted in the tree, their power characteristics are propagated to the parents::
+
+  SoC (600mW - 5900mW)
+   |
+   |-- pkg (400mW - 3100mW)
+   |    |
+   |    |-- pd0 (100mW - 700mW)
+   |    |
+   |    `-- pd1 (300mW - 2400mW)
+   |
+   `-- pd2 (200mW - 2800mW)
+
+Each node have a weight on a 2^10 basis reflecting the percentage of power consumption along the siblings::
+
+  SoC (w=1024)
+   |
+   |-- pkg (w=538)
+   |    |
+   |    |-- pd0 (w=231)
+   |    |
+   |    `-- pd1 (w=794)
+   |
+   `-- pd2 (w=486)
+
+   Note the sum of weights at the same level are equal to 1024.
+
+When a power limitation is applied to a node, then it is distributed along the children given their weights. For example, if we set a power limitation of 3200mW at the 'SoC' root node, the resulting tree will be::
+
+  SoC (w=1024) <--- power_limit = 3200mW
+   |
+   |-- pkg (w=538) --> power_limit = 1681mW
+   |    |
+   |    |-- pd0 (w=231) --> power_limit = 378mW
+   |    |
+   |    `-- pd1 (w=794) --> power_limit = 1303mW
+   |
+   `-- pd2 (w=486) --> power_limit = 1519mW
+
+
+Flat description
+----------------
+
+A root node is created and it is the parent of all the nodes. This
+description is the simplest one and it is supposed to give to user
+space a flat representation of all the devices supporting the power
+limitation without any power limitation distribution.
+
+Hierarchical description
+------------------------
+
+The different devices supporting the power limitation are represented
+hierarchically. There is one root node, all intermediate nodes are
+grouping the child nodes which can be intermediate nodes also or real
+devices.
+
+The intermediate nodes aggregate the power information and allows to
+set the power limit given the weight of the nodes.
+
+User space API
+==============
+
+As stated in the overview, the DTPM framework is built on top of the
+powercap framework. Thus the sysfs interface is the same, please refer
+to the powercap documentation for further details.
+
+ * power_uw: Instantaneous power consumption. If the node is an
+   intermediate node, then the power consumption will be the sum of all
+   children power consumption.
+
+ * max_power_range_uw: The power range resulting of the maximum power
+   minus the minimum power.
+
+ * name: The name of the node. This is implementation dependent. Even
+   if it is not recommended for the user space, several nodes can have
+   the same name.
+
+ * constraint_X_name: The name of the constraint.
+
+ * constraint_X_max_power_uw: The maximum power limit to be applicable
+   to the node.
+
+ * constraint_X_power_limit_uw: The power limit to be applied to the
+   node. If the value contained in constraint_X_max_power_uw is set,
+   the constraint will be removed.
+
+ * constraint_X_time_window_us: The meaning of this file will depend
+   on the constraint number.
+
+Constraints
+-----------
+
+ * Constraint 0: The power limitation is immediately applied, without
+   limitation in time.
+
+Kernel API
+==========
+
+Overview
+--------
+
+The DTPM framework has no power limiting backend support. It is
+generic and provides a set of API to let the different drivers to
+implement the backend part for the power limitation and create the
+power constraints tree.
+
+It is up to the platform to provide the initialization function to
+allocate and link the different nodes of the tree.
+
+A special macro has the role of declaring a node and the corresponding
+initialization function via a description structure. This one contains
+an optional parent field allowing to hook different devices to an
+already existing tree at boot time.
+
+For instance::
+
+	struct dtpm_descr my_descr = {
+		.name = "my_name",
+		.init = my_init_func,
+	};
+
+	DTPM_DECLARE(my_descr);
+
+The nodes of the DTPM tree are described with dtpm structure. The
+steps to add a new power limitable device is done in three steps:
+
+ * Allocate the dtpm node
+ * Set the power number of the dtpm node
+ * Register the dtpm node
+
+The registration of the dtpm node is done with the powercap
+ops. Basically, it must implements the callbacks to get and set the
+power and the limit.
+
+Alternatively, if the node to be inserted is an intermediate one, then
+a simple function to insert it as a future parent is available.
+
+If a device has its power characteristics changing, then the tree must
+be updated with the new power numbers and weights.
+
+Nomenclature
+------------
+
+ * dtpm_alloc() : Allocate and initialize a dtpm structure
+
+ * dtpm_register() : Add the dtpm node to the tree
+
+ * dtpm_unregister() : Remove the dtpm node from the tree
+
+ * dtpm_update_power() : Update the power characteristics of the dtpm node

drivers/powercap/Kconfig

@@ -43,4 +43,17 @@ config IDLE_INJECT
 	  CPUs for power capping. Idle period can be injected
 	  synchronously on a set of specified CPUs or alternatively
 	  on a per CPU basis.
+
+config DTPM
+	bool "Power capping for Dynamic Thermal Power Management"
+	help
+	  This enables support for the power capping for the dynamic
+	  thermal power management userspace engine.
+
+config DTPM_CPU
+	bool "Add CPU power capping based on the energy model"
+	depends on DTPM && ENERGY_MODEL
+	help
+	  This enables support for CPU power limitation based on
+	  energy model.
 endif

drivers/powercap/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_DTPM) += dtpm.o
+obj-$(CONFIG_DTPM_CPU) += dtpm_cpu.o
 obj-$(CONFIG_POWERCAP)	+= powercap_sys.o
 obj-$(CONFIG_INTEL_RAPL_CORE) += intel_rapl_common.o
 obj-$(CONFIG_INTEL_RAPL) += intel_rapl_msr.o

drivers/powercap/dtpm_cpu.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Linaro Limited
+ *
+ * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ * The DTPM CPU is based on the energy model. It hooks the CPU in the
+ * DTPM tree which in turns update the power number by propagating the
+ * power number from the CPU energy model information to the parents.
+ *
+ * The association between the power and the performance state, allows
+ * to set the power of the CPU at the OPP granularity.
+ *
+ * The CPU hotplug is supported and the power numbers will be updated
+ * if a CPU is hot plugged / unplugged.
+ */
+#include <linux/cpumask.h>
+#include <linux/cpufreq.h>
+#include <linux/cpuhotplug.h>
+#include <linux/dtpm.h>
+#include <linux/energy_model.h>
+#include <linux/pm_qos.h>
+#include <linux/slab.h>
+#include <linux/units.h>
+
+static struct dtpm *__parent;
+
+static DEFINE_PER_CPU(struct dtpm *, dtpm_per_cpu);
+
+struct dtpm_cpu {
+	struct freq_qos_request qos_req;
+	int cpu;
+};
+
+/*
+ * When a new CPU is inserted at hotplug or boot time, add the power
+ * contribution and update the dtpm tree.
+ */
+static int power_add(struct dtpm *dtpm, struct em_perf_domain *em)
+{
+	u64 power_min, power_max;
+
+	power_min = em->table[0].power;
+	power_min *= MICROWATT_PER_MILLIWATT;
+	power_min += dtpm->power_min;
+
+	power_max = em->table[em->nr_perf_states - 1].power;
+	power_max *= MICROWATT_PER_MILLIWATT;
+	power_max += dtpm->power_max;
+
+	return dtpm_update_power(dtpm, power_min, power_max);
+}
+
+/*
+ * When a CPU is unplugged, remove its power contribution from the
+ * dtpm tree.
+ */
+static int power_sub(struct dtpm *dtpm, struct em_perf_domain *em)
+{
+	u64 power_min, power_max;
+
+	power_min = em->table[0].power;
+	power_min *= MICROWATT_PER_MILLIWATT;
+	power_min = dtpm->power_min - power_min;
+
+	power_max = em->table[em->nr_perf_states - 1].power;
+	power_max *= MICROWATT_PER_MILLIWATT;
+	power_max = dtpm->power_max - power_max;
+
+	return dtpm_update_power(dtpm, power_min, power_max);
+}
+
+static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
+{
+	struct dtpm_cpu *dtpm_cpu = dtpm->private;
+	struct em_perf_domain *pd;
+	struct cpumask cpus;
+	unsigned long freq;
+	u64 power;
+	int i, nr_cpus;
+
+	pd = em_cpu_get(dtpm_cpu->cpu);
+
+	cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
+
+	nr_cpus = cpumask_weight(&cpus);
+
+	for (i = 0; i < pd->nr_perf_states; i++) {
+
+		power = pd->table[i].power * MICROWATT_PER_MILLIWATT * nr_cpus;
+
+		if (power > power_limit)
+			break;
+	}
+
+	freq = pd->table[i - 1].frequency;
+
+	freq_qos_update_request(&dtpm_cpu->qos_req, freq);
+
+	power_limit = pd->table[i - 1].power *
+		MICROWATT_PER_MILLIWATT * nr_cpus;
+
+	return power_limit;
+}
+
+static u64 get_pd_power_uw(struct dtpm *dtpm)
+{
+	struct dtpm_cpu *dtpm_cpu = dtpm->private;
+	struct em_perf_domain *pd;
+	struct cpumask cpus;
+	unsigned long freq;
+	int i, nr_cpus;
+
+	pd = em_cpu_get(dtpm_cpu->cpu);
+	freq = cpufreq_quick_get(dtpm_cpu->cpu);
+	cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
+	nr_cpus = cpumask_weight(&cpus);
+
+	for (i = 0; i < pd->nr_perf_states; i++) {
+
+		if (pd->table[i].frequency < freq)
+			continue;
+
+		return pd->table[i].power *
+			MICROWATT_PER_MILLIWATT * nr_cpus;
+	}
+
+	return 0;
+}
+
+static void pd_release(struct dtpm *dtpm)
+{
+	struct dtpm_cpu *dtpm_cpu = dtpm->private;
+
+	if (freq_qos_request_active(&dtpm_cpu->qos_req))
+		freq_qos_remove_request(&dtpm_cpu->qos_req);
+
+	kfree(dtpm_cpu);
+}
+
+static struct dtpm_ops dtpm_ops = {
+	.set_power_uw = set_pd_power_limit,
+	.get_power_uw = get_pd_power_uw,
+	.release = pd_release,
+};
+
+static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
+{
+	struct cpufreq_policy *policy;
+	struct em_perf_domain *pd;
+	struct dtpm *dtpm;
+
+	policy = cpufreq_cpu_get(cpu);
+
+	if (!policy)
+		return 0;
+
+	pd = em_cpu_get(cpu);
+	if (!pd)
+		return -EINVAL;
+
+	dtpm = per_cpu(dtpm_per_cpu, cpu);
+
+	power_sub(dtpm, pd);
+
+	if (cpumask_weight(policy->cpus) != 1)
+		return 0;
+
+	for_each_cpu(cpu, policy->related_cpus)
+		per_cpu(dtpm_per_cpu, cpu) = NULL;
+
+	dtpm_unregister(dtpm);
+
+	return 0;
+}
+
+static int cpuhp_dtpm_cpu_online(unsigned int cpu)
+{
+	struct dtpm *dtpm;
+	struct dtpm_cpu *dtpm_cpu;
+	struct cpufreq_policy *policy;
+	struct em_perf_domain *pd;
+	char name[CPUFREQ_NAME_LEN];
+	int ret = -ENOMEM;
+
+	policy = cpufreq_cpu_get(cpu);
+
+	if (!policy)
+		return 0;
+
+	pd = em_cpu_get(cpu);
+	if (!pd)
+		return -EINVAL;
+
+	dtpm = per_cpu(dtpm_per_cpu, cpu);
+	if (dtpm)
+		return power_add(dtpm, pd);
+
+	dtpm = dtpm_alloc(&dtpm_ops);
+	if (!dtpm)
+		return -EINVAL;
+
+	dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
+	if (!dtpm_cpu)
+		goto out_kfree_dtpm;
+
+	dtpm->private = dtpm_cpu;
+	dtpm_cpu->cpu = cpu;
+
+	for_each_cpu(cpu, policy->related_cpus)
+		per_cpu(dtpm_per_cpu, cpu) = dtpm;
+
+	sprintf(name, "cpu%d", dtpm_cpu->cpu);
+
+	ret = dtpm_register(name, dtpm, __parent);
+	if (ret)
+		goto out_kfree_dtpm_cpu;
+
+	ret = power_add(dtpm, pd);
+	if (ret)
+		goto out_dtpm_unregister;
+
+	ret = freq_qos_add_request(&policy->constraints,
+				   &dtpm_cpu->qos_req, FREQ_QOS_MAX,
+				   pd->table[pd->nr_perf_states - 1].frequency);
+	if (ret)
+		goto out_power_sub;
+
+	return 0;
+
+out_power_sub:
+	power_sub(dtpm, pd);
+
+out_dtpm_unregister:
+	dtpm_unregister(dtpm);
+	dtpm_cpu = NULL;
+	dtpm = NULL;
+
+out_kfree_dtpm_cpu:
+	for_each_cpu(cpu, policy->related_cpus)
+		per_cpu(dtpm_per_cpu, cpu) = NULL;
+	kfree(dtpm_cpu);
+
+out_kfree_dtpm:
+	kfree(dtpm);
+	return ret;
+}
+
+int dtpm_register_cpu(struct dtpm *parent)
+{
+	__parent = parent;
+
+	return cpuhp_setup_state(CPUHP_AP_DTPM_CPU_ONLINE,
+				 "dtpm_cpu:online",
+				 cpuhp_dtpm_cpu_online,
+				 cpuhp_dtpm_cpu_offline);
+}

drivers/powercap/intel_rapl_common.c

@@ -547,7 +547,7 @@ static void rapl_init_domains(struct rapl_package *rp)
 
 		if (i == RAPL_DOMAIN_PLATFORM && rp->id > 0) {
 			snprintf(rd->name, RAPL_DOMAIN_NAME_LENGTH, "psys-%d",
-				cpu_data(rp->lead_cpu).phys_proc_id);
+				topology_physical_package_id(rp->lead_cpu));
 		} else
 			snprintf(rd->name, RAPL_DOMAIN_NAME_LENGTH, "%s",
 				rapl_domain_names[i]);
@@ -1049,6 +1049,7 @@ static const struct x86_cpu_id rapl_ids[] __initconst = {
 	X86_MATCH_INTEL_FAM6_MODEL(TIGERLAKE,		&rapl_defaults_core),
 	X86_MATCH_INTEL_FAM6_MODEL(ROCKETLAKE,		&rapl_defaults_core),
 	X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE,		&rapl_defaults_core),
+	X86_MATCH_INTEL_FAM6_MODEL(ALDERLAKE_L,		&rapl_defaults_core),
 	X86_MATCH_INTEL_FAM6_MODEL(SAPPHIRERAPIDS_X,	&rapl_defaults_spr_server),
 	X86_MATCH_INTEL_FAM6_MODEL(LAKEFIELD,		&rapl_defaults_core),
 
@@ -1309,7 +1310,6 @@ struct rapl_package *rapl_add_package(int cpu, struct rapl_if_priv *priv)
 {
 	int id = topology_logical_die_id(cpu);
 	struct rapl_package *rp;
-	struct cpuinfo_x86 *c = &cpu_data(cpu);
 	int ret;
 
 	if (!rapl_defaults)
@@ -1326,10 +1326,11 @@ struct rapl_package *rapl_add_package(int cpu, struct rapl_if_priv *priv)
 
 	if (topology_max_die_per_package() > 1)
 		snprintf(rp->name, PACKAGE_DOMAIN_NAME_LENGTH,
-			 "package-%d-die-%d", c->phys_proc_id, c->cpu_die_id);
+			 "package-%d-die-%d",
+			 topology_physical_package_id(cpu), topology_die_id(cpu));
 	else
 		snprintf(rp->name, PACKAGE_DOMAIN_NAME_LENGTH, "package-%d",
-			 c->phys_proc_id);
+			 topology_physical_package_id(cpu));
 
 	/* check if the package contains valid domains */
 	if (rapl_detect_domains(rp, cpu) || rapl_defaults->check_unit(rp, cpu)) {

include/asm-generic/vmlinux.lds.h

@@ -316,6 +316,16 @@
 #define THERMAL_TABLE(name)
 #endif
 
+#ifdef CONFIG_DTPM
+#define DTPM_TABLE()							\
+	. = ALIGN(8);							\
+	__dtpm_table = .;						\
+	KEEP(*(__dtpm_table))						\
+	__dtpm_table_end = .;
+#else
+#define DTPM_TABLE()
+#endif
+
 #define KERNEL_DTB()							\
 	STRUCT_ALIGN();							\
 	__dtb_start = .;						\
@@ -733,6 +743,7 @@
 	ACPI_PROBE_TABLE(irqchip)					\
 	ACPI_PROBE_TABLE(timer)						\
 	THERMAL_TABLE(governor)						\
+	DTPM_TABLE()							\
 	EARLYCON_TABLE()						\
 	LSM_TABLE()							\
 	EARLY_LSM_TABLE()						\

include/linux/cpuhotplug.h

@@ -193,6 +193,7 @@ enum cpuhp_state {
 	CPUHP_AP_ONLINE_DYN_END		= CPUHP_AP_ONLINE_DYN + 30,
 	CPUHP_AP_X86_HPET_ONLINE,
 	CPUHP_AP_X86_KVM_CLK_ONLINE,
+	CPUHP_AP_DTPM_CPU_ONLINE,
 	CPUHP_AP_ACTIVE,
 	CPUHP_ONLINE,
 };

include/linux/dtpm.h

+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Linaro Ltd
+ *
+ * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ */
+#ifndef ___DTPM_H__
+#define ___DTPM_H__
+
+#include <linux/powercap.h>
+
+#define MAX_DTPM_DESCR 8
+#define MAX_DTPM_CONSTRAINTS 1
+
+struct dtpm {
+	struct powercap_zone zone;
+	struct dtpm *parent;
+	struct list_head sibling;
+	struct list_head children;
+	struct dtpm_ops *ops;
+	unsigned long flags;
+	u64 power_limit;
+	u64 power_max;
+	u64 power_min;
+	int weight;
+	void *private;
+};
+
+struct dtpm_ops {
+	u64 (*set_power_uw)(struct dtpm *, u64);
+	u64 (*get_power_uw)(struct dtpm *);
+	void (*release)(struct dtpm *);
+};
+
+struct dtpm_descr;
+
+typedef int (*dtpm_init_t)(struct dtpm_descr *);
+
+struct dtpm_descr {
+	struct dtpm *parent;
+	const char *name;
+	dtpm_init_t init;
+};
+
+/* Init section thermal table */
+extern struct dtpm_descr *__dtpm_table[];
+extern struct dtpm_descr *__dtpm_table_end[];
+
+#define DTPM_TABLE_ENTRY(name)			\
+	static typeof(name) *__dtpm_table_entry_##name	\
+	__used __section("__dtpm_table") = &name
+
+#define DTPM_DECLARE(name)	DTPM_TABLE_ENTRY(name)
+
+#define for_each_dtpm_table(__dtpm)	\
+	for (__dtpm = __dtpm_table;	\
+	     __dtpm < __dtpm_table_end;	\
+	     __dtpm++)
+
+static inline struct dtpm *to_dtpm(struct powercap_zone *zone)
+{
+	return container_of(zone, struct dtpm, zone);
+}
+
+int dtpm_update_power(struct dtpm *dtpm, u64 power_min, u64 power_max);
+
+int dtpm_release_zone(struct powercap_zone *pcz);
+
+struct dtpm *dtpm_alloc(struct dtpm_ops *ops);
+
+void dtpm_unregister(struct dtpm *dtpm);
+
+int dtpm_register(const char *name, struct dtpm *dtpm, struct dtpm *parent);
+
+int dtpm_register_cpu(struct dtpm *parent);
+
+#endif

include/linux/units.h

@@ -4,6 +4,10 @@
 
 #include <linux/math.h>
 
+#define MILLIWATT_PER_WATT	1000L
+#define MICROWATT_PER_MILLIWATT	1000L
+#define MICROWATT_PER_WATT	1000000L
+
 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
 
 static inline long milli_kelvin_to_millicelsius(long t)

kernel/power/Kconfig

@@ -139,7 +139,6 @@ config PM_SLEEP_SMP_NONZERO_CPU
 config PM_AUTOSLEEP
 	bool "Opportunistic sleep"
 	depends on PM_SLEEP
-	default n
 	help
 	Allow the kernel to trigger a system transition into a global sleep
 	state automatically whenever there are no active wakeup sources.
@@ -147,7 +146,6 @@ config PM_AUTOSLEEP
 config PM_WAKELOCKS
 	bool "User space wakeup sources interface"
 	depends on PM_SLEEP
-	default n
 	help
 	Allow user space to create, activate and deactivate wakeup source
 	objects with the help of a sysfs-based interface.
@@ -293,7 +291,6 @@ config PM_GENERIC_DOMAINS
 config WQ_POWER_EFFICIENT_DEFAULT
 	bool "Enable workqueue power-efficient mode by default"
 	depends on PM
-	default n
 	help
 	  Per-cpu workqueues are generally preferred because they show
 	  better performance thanks to cache locality; unfortunately,
@@ -322,15 +319,14 @@ config CPU_PM
 	bool
 
 config ENERGY_MODEL
-	bool "Energy Model for CPUs"
+	bool "Energy Model for devices with DVFS (CPUs, GPUs, etc)"
 	depends on SMP
 	depends on CPU_FREQ
-	default n
 	help
 	  Several subsystems (thermal and/or the task scheduler for example)
-	  can leverage information about the energy consumed by CPUs to make
-	  smarter decisions. This config option enables the framework from
-	  which subsystems can access the energy models.
+	  can leverage information about the energy consumed by devices to
+	  make smarter decisions. This config option enables the framework
+	  from which subsystems can access the energy models.
 
 	  The exact usage of the energy model is subsystem-dependent.