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authorLinus Torvalds2011-10-25 15:18:39 +0200
committerLinus Torvalds2011-10-25 15:18:39 +0200
commit7e0bb71e75020348bee523720a0c2f04cc72f540 (patch)
tree1a22d65bbce34e8cc0f82c543c9486ffb58332f7 /drivers/base
parentb9e2780d576a010d4aba1e69f247170bf3718d6b (diff)
parent0ab1e79b825a5cd8aeb3b34d89c9a89dea900056 (diff)
Merge branch 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
* 'pm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (63 commits) PM / Clocks: Remove redundant NULL checks before kfree() PM / Documentation: Update docs about suspend and CPU hotplug ACPI / PM: Add Sony VGN-FW21E to nonvs blacklist. ARM: mach-shmobile: sh7372 A4R support (v4) ARM: mach-shmobile: sh7372 A3SP support (v4) PM / Sleep: Mark devices involved in wakeup signaling during suspend PM / Hibernate: Improve performance of LZO/plain hibernation, checksum image PM / Hibernate: Do not initialize static and extern variables to 0 PM / Freezer: Make fake_signal_wake_up() wake TASK_KILLABLE tasks too PM / Hibernate: Add resumedelay kernel param in addition to resumewait MAINTAINERS: Update linux-pm list address PM / ACPI: Blacklist Vaio VGN-FW520F machine known to require acpi_sleep=nonvs PM / ACPI: Blacklist Sony Vaio known to require acpi_sleep=nonvs PM / Hibernate: Add resumewait param to support MMC-like devices as resume file PM / Hibernate: Fix typo in a kerneldoc comment PM / Hibernate: Freeze kernel threads after preallocating memory PM: Update the policy on default wakeup settings PM / VT: Cleanup #if defined uglyness and fix compile error PM / Suspend: Off by one in pm_suspend() PM / Hibernate: Include storage keys in hibernation image on s390 ...
Diffstat (limited to 'drivers/base')
-rw-r--r--drivers/base/power/Makefile4
-rw-r--r--drivers/base/power/clock_ops.c127
-rw-r--r--drivers/base/power/common.c86
-rw-r--r--drivers/base/power/domain.c352
-rw-r--r--drivers/base/power/main.c42
-rw-r--r--drivers/base/power/opp.c30
-rw-r--r--drivers/base/power/power.h10
-rw-r--r--drivers/base/power/qos.c419
-rw-r--r--drivers/base/power/runtime.c127
-rw-r--r--drivers/base/power/wakeup.c4
10 files changed, 931 insertions, 270 deletions
diff --git a/drivers/base/power/Makefile b/drivers/base/power/Makefile
index 2639ae79a372..81676dd17900 100644
--- a/drivers/base/power/Makefile
+++ b/drivers/base/power/Makefile
@@ -1,4 +1,4 @@
-obj-$(CONFIG_PM) += sysfs.o generic_ops.o
+obj-$(CONFIG_PM) += sysfs.o generic_ops.o common.o qos.o
obj-$(CONFIG_PM_SLEEP) += main.o wakeup.o
obj-$(CONFIG_PM_RUNTIME) += runtime.o
obj-$(CONFIG_PM_TRACE_RTC) += trace.o
@@ -6,4 +6,4 @@ obj-$(CONFIG_PM_OPP) += opp.o
obj-$(CONFIG_PM_GENERIC_DOMAINS) += domain.o
obj-$(CONFIG_HAVE_CLK) += clock_ops.o
-ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG \ No newline at end of file
+ccflags-$(CONFIG_DEBUG_DRIVER) := -DDEBUG
diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
index b97294e2d95b..5f0f85d5c576 100644
--- a/drivers/base/power/clock_ops.c
+++ b/drivers/base/power/clock_ops.c
@@ -10,18 +10,13 @@
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/pm.h>
-#include <linux/pm_runtime.h>
+#include <linux/pm_clock.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/err.h>
#ifdef CONFIG_PM
-struct pm_clk_data {
- struct list_head clock_list;
- spinlock_t lock;
-};
-
enum pce_status {
PCE_STATUS_NONE = 0,
PCE_STATUS_ACQUIRED,
@@ -36,11 +31,6 @@ struct pm_clock_entry {
enum pce_status status;
};
-static struct pm_clk_data *__to_pcd(struct device *dev)
-{
- return dev ? dev->power.subsys_data : NULL;
-}
-
/**
* pm_clk_acquire - Acquire a device clock.
* @dev: Device whose clock is to be acquired.
@@ -67,10 +57,10 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
*/
int pm_clk_add(struct device *dev, const char *con_id)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce;
- if (!pcd)
+ if (!psd)
return -EINVAL;
ce = kzalloc(sizeof(*ce), GFP_KERNEL);
@@ -91,9 +81,9 @@ int pm_clk_add(struct device *dev, const char *con_id)
pm_clk_acquire(dev, ce);
- spin_lock_irq(&pcd->lock);
- list_add_tail(&ce->node, &pcd->clock_list);
- spin_unlock_irq(&pcd->lock);
+ spin_lock_irq(&psd->lock);
+ list_add_tail(&ce->node, &psd->clock_list);
+ spin_unlock_irq(&psd->lock);
return 0;
}
@@ -114,9 +104,7 @@ static void __pm_clk_remove(struct pm_clock_entry *ce)
clk_put(ce->clk);
}
- if (ce->con_id)
- kfree(ce->con_id);
-
+ kfree(ce->con_id);
kfree(ce);
}
@@ -130,15 +118,15 @@ static void __pm_clk_remove(struct pm_clock_entry *ce)
*/
void pm_clk_remove(struct device *dev, const char *con_id)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce;
- if (!pcd)
+ if (!psd)
return;
- spin_lock_irq(&pcd->lock);
+ spin_lock_irq(&psd->lock);
- list_for_each_entry(ce, &pcd->clock_list, node) {
+ list_for_each_entry(ce, &psd->clock_list, node) {
if (!con_id && !ce->con_id)
goto remove;
else if (!con_id || !ce->con_id)
@@ -147,12 +135,12 @@ void pm_clk_remove(struct device *dev, const char *con_id)
goto remove;
}
- spin_unlock_irq(&pcd->lock);
+ spin_unlock_irq(&psd->lock);
return;
remove:
list_del(&ce->node);
- spin_unlock_irq(&pcd->lock);
+ spin_unlock_irq(&psd->lock);
__pm_clk_remove(ce);
}
@@ -161,23 +149,27 @@ void pm_clk_remove(struct device *dev, const char *con_id)
* pm_clk_init - Initialize a device's list of power management clocks.
* @dev: Device to initialize the list of PM clocks for.
*
- * Allocate a struct pm_clk_data object, initialize its lock member and
- * make the @dev's power.subsys_data field point to it.
+ * Initialize the lock and clock_list members of the device's pm_subsys_data
+ * object.
*/
-int pm_clk_init(struct device *dev)
+void pm_clk_init(struct device *dev)
{
- struct pm_clk_data *pcd;
-
- pcd = kzalloc(sizeof(*pcd), GFP_KERNEL);
- if (!pcd) {
- dev_err(dev, "Not enough memory for PM clock data.\n");
- return -ENOMEM;
- }
+ struct pm_subsys_data *psd = dev_to_psd(dev);
+ if (psd)
+ INIT_LIST_HEAD(&psd->clock_list);
+}
- INIT_LIST_HEAD(&pcd->clock_list);
- spin_lock_init(&pcd->lock);
- dev->power.subsys_data = pcd;
- return 0;
+/**
+ * pm_clk_create - Create and initialize a device's list of PM clocks.
+ * @dev: Device to create and initialize the list of PM clocks for.
+ *
+ * Allocate a struct pm_subsys_data object, initialize its lock and clock_list
+ * members and make the @dev's power.subsys_data field point to it.
+ */
+int pm_clk_create(struct device *dev)
+{
+ int ret = dev_pm_get_subsys_data(dev);
+ return ret < 0 ? ret : 0;
}
/**
@@ -185,29 +177,28 @@ int pm_clk_init(struct device *dev)
* @dev: Device to destroy the list of PM clocks for.
*
* Clear the @dev's power.subsys_data field, remove the list of clock entries
- * from the struct pm_clk_data object pointed to by it before and free
+ * from the struct pm_subsys_data object pointed to by it before and free
* that object.
*/
void pm_clk_destroy(struct device *dev)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce, *c;
struct list_head list;
- if (!pcd)
+ if (!psd)
return;
- dev->power.subsys_data = NULL;
INIT_LIST_HEAD(&list);
- spin_lock_irq(&pcd->lock);
+ spin_lock_irq(&psd->lock);
- list_for_each_entry_safe_reverse(ce, c, &pcd->clock_list, node)
+ list_for_each_entry_safe_reverse(ce, c, &psd->clock_list, node)
list_move(&ce->node, &list);
- spin_unlock_irq(&pcd->lock);
+ spin_unlock_irq(&psd->lock);
- kfree(pcd);
+ dev_pm_put_subsys_data(dev);
list_for_each_entry_safe_reverse(ce, c, &list, node) {
list_del(&ce->node);
@@ -225,25 +216,25 @@ void pm_clk_destroy(struct device *dev)
*/
int pm_clk_suspend(struct device *dev)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce;
unsigned long flags;
dev_dbg(dev, "%s()\n", __func__);
- if (!pcd)
+ if (!psd)
return 0;
- spin_lock_irqsave(&pcd->lock, flags);
+ spin_lock_irqsave(&psd->lock, flags);
- list_for_each_entry_reverse(ce, &pcd->clock_list, node) {
+ list_for_each_entry_reverse(ce, &psd->clock_list, node) {
if (ce->status < PCE_STATUS_ERROR) {
clk_disable(ce->clk);
ce->status = PCE_STATUS_ACQUIRED;
}
}
- spin_unlock_irqrestore(&pcd->lock, flags);
+ spin_unlock_irqrestore(&psd->lock, flags);
return 0;
}
@@ -254,25 +245,25 @@ int pm_clk_suspend(struct device *dev)
*/
int pm_clk_resume(struct device *dev)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce;
unsigned long flags;
dev_dbg(dev, "%s()\n", __func__);
- if (!pcd)
+ if (!psd)
return 0;
- spin_lock_irqsave(&pcd->lock, flags);
+ spin_lock_irqsave(&psd->lock, flags);
- list_for_each_entry(ce, &pcd->clock_list, node) {
+ list_for_each_entry(ce, &psd->clock_list, node) {
if (ce->status < PCE_STATUS_ERROR) {
clk_enable(ce->clk);
ce->status = PCE_STATUS_ENABLED;
}
}
- spin_unlock_irqrestore(&pcd->lock, flags);
+ spin_unlock_irqrestore(&psd->lock, flags);
return 0;
}
@@ -310,7 +301,7 @@ static int pm_clk_notify(struct notifier_block *nb,
if (dev->pm_domain)
break;
- error = pm_clk_init(dev);
+ error = pm_clk_create(dev);
if (error)
break;
@@ -345,22 +336,22 @@ static int pm_clk_notify(struct notifier_block *nb,
*/
int pm_clk_suspend(struct device *dev)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce;
unsigned long flags;
dev_dbg(dev, "%s()\n", __func__);
/* If there is no driver, the clocks are already disabled. */
- if (!pcd || !dev->driver)
+ if (!psd || !dev->driver)
return 0;
- spin_lock_irqsave(&pcd->lock, flags);
+ spin_lock_irqsave(&psd->lock, flags);
- list_for_each_entry_reverse(ce, &pcd->clock_list, node)
+ list_for_each_entry_reverse(ce, &psd->clock_list, node)
clk_disable(ce->clk);
- spin_unlock_irqrestore(&pcd->lock, flags);
+ spin_unlock_irqrestore(&psd->lock, flags);
return 0;
}
@@ -371,22 +362,22 @@ int pm_clk_suspend(struct device *dev)
*/
int pm_clk_resume(struct device *dev)
{
- struct pm_clk_data *pcd = __to_pcd(dev);
+ struct pm_subsys_data *psd = dev_to_psd(dev);
struct pm_clock_entry *ce;
unsigned long flags;
dev_dbg(dev, "%s()\n", __func__);
/* If there is no driver, the clocks should remain disabled. */
- if (!pcd || !dev->driver)
+ if (!psd || !dev->driver)
return 0;
- spin_lock_irqsave(&pcd->lock, flags);
+ spin_lock_irqsave(&psd->lock, flags);
- list_for_each_entry(ce, &pcd->clock_list, node)
+ list_for_each_entry(ce, &psd->clock_list, node)
clk_enable(ce->clk);
- spin_unlock_irqrestore(&pcd->lock, flags);
+ spin_unlock_irqrestore(&psd->lock, flags);
return 0;
}
diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
new file mode 100644
index 000000000000..29820c396182
--- /dev/null
+++ b/drivers/base/power/common.c
@@ -0,0 +1,86 @@
+/*
+ * drivers/base/power/common.c - Common device power management code.
+ *
+ * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/pm_clock.h>
+
+/**
+ * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
+ * @dev: Device to handle.
+ *
+ * If power.subsys_data is NULL, point it to a new object, otherwise increment
+ * its reference counter. Return 1 if a new object has been created, otherwise
+ * return 0 or error code.
+ */
+int dev_pm_get_subsys_data(struct device *dev)
+{
+ struct pm_subsys_data *psd;
+ int ret = 0;
+
+ psd = kzalloc(sizeof(*psd), GFP_KERNEL);
+ if (!psd)
+ return -ENOMEM;
+
+ spin_lock_irq(&dev->power.lock);
+
+ if (dev->power.subsys_data) {
+ dev->power.subsys_data->refcount++;
+ } else {
+ spin_lock_init(&psd->lock);
+ psd->refcount = 1;
+ dev->power.subsys_data = psd;
+ pm_clk_init(dev);
+ psd = NULL;
+ ret = 1;
+ }
+
+ spin_unlock_irq(&dev->power.lock);
+
+ /* kfree() verifies that its argument is nonzero. */
+ kfree(psd);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
+
+/**
+ * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
+ * @dev: Device to handle.
+ *
+ * If the reference counter of power.subsys_data is zero after dropping the
+ * reference, power.subsys_data is removed. Return 1 if that happens or 0
+ * otherwise.
+ */
+int dev_pm_put_subsys_data(struct device *dev)
+{
+ struct pm_subsys_data *psd;
+ int ret = 0;
+
+ spin_lock_irq(&dev->power.lock);
+
+ psd = dev_to_psd(dev);
+ if (!psd) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (--psd->refcount == 0) {
+ dev->power.subsys_data = NULL;
+ kfree(psd);
+ ret = 1;
+ }
+
+ out:
+ spin_unlock_irq(&dev->power.lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 1c374579407c..6790cf7eba5a 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -29,10 +29,20 @@ static struct generic_pm_domain *dev_to_genpd(struct device *dev)
return pd_to_genpd(dev->pm_domain);
}
-static void genpd_sd_counter_dec(struct generic_pm_domain *genpd)
+static bool genpd_sd_counter_dec(struct generic_pm_domain *genpd)
{
- if (!WARN_ON(genpd->sd_count == 0))
- genpd->sd_count--;
+ bool ret = false;
+
+ if (!WARN_ON(atomic_read(&genpd->sd_count) == 0))
+ ret = !!atomic_dec_and_test(&genpd->sd_count);
+
+ return ret;
+}
+
+static void genpd_sd_counter_inc(struct generic_pm_domain *genpd)
+{
+ atomic_inc(&genpd->sd_count);
+ smp_mb__after_atomic_inc();
}
static void genpd_acquire_lock(struct generic_pm_domain *genpd)
@@ -71,81 +81,119 @@ static void genpd_set_active(struct generic_pm_domain *genpd)
}
/**
- * pm_genpd_poweron - Restore power to a given PM domain and its parents.
+ * __pm_genpd_poweron - Restore power to a given PM domain and its masters.
* @genpd: PM domain to power up.
*
- * Restore power to @genpd and all of its parents so that it is possible to
+ * Restore power to @genpd and all of its masters so that it is possible to
* resume a device belonging to it.
*/
-int pm_genpd_poweron(struct generic_pm_domain *genpd)
+int __pm_genpd_poweron(struct generic_pm_domain *genpd)
+ __releases(&genpd->lock) __acquires(&genpd->lock)
{
- struct generic_pm_domain *parent = genpd->parent;
+ struct gpd_link *link;
+ DEFINE_WAIT(wait);
int ret = 0;
- start:
- if (parent) {
- genpd_acquire_lock(parent);
- mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
- } else {
+ /* If the domain's master is being waited for, we have to wait too. */
+ for (;;) {
+ prepare_to_wait(&genpd->status_wait_queue, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (genpd->status != GPD_STATE_WAIT_MASTER)
+ break;
+ mutex_unlock(&genpd->lock);
+
+ schedule();
+
mutex_lock(&genpd->lock);
}
+ finish_wait(&genpd->status_wait_queue, &wait);
if (genpd->status == GPD_STATE_ACTIVE
|| (genpd->prepared_count > 0 && genpd->suspend_power_off))
- goto out;
+ return 0;
if (genpd->status != GPD_STATE_POWER_OFF) {
genpd_set_active(genpd);
- goto out;
+ return 0;
}
- if (parent && parent->status != GPD_STATE_ACTIVE) {
+ /*
+ * The list is guaranteed not to change while the loop below is being
+ * executed, unless one of the masters' .power_on() callbacks fiddles
+ * with it.
+ */
+ list_for_each_entry(link, &genpd->slave_links, slave_node) {
+ genpd_sd_counter_inc(link->master);
+ genpd->status = GPD_STATE_WAIT_MASTER;
+
mutex_unlock(&genpd->lock);
- genpd_release_lock(parent);
- ret = pm_genpd_poweron(parent);
- if (ret)
- return ret;
+ ret = pm_genpd_poweron(link->master);
- goto start;
+ mutex_lock(&genpd->lock);
+
+ /*
+ * The "wait for parent" status is guaranteed not to change
+ * while the master is powering on.
+ */
+ genpd->status = GPD_STATE_POWER_OFF;
+ wake_up_all(&genpd->status_wait_queue);
+ if (ret) {
+ genpd_sd_counter_dec(link->master);
+ goto err;
+ }
}
if (genpd->power_on) {
ret = genpd->power_on(genpd);
if (ret)
- goto out;
+ goto err;
}
genpd_set_active(genpd);
- if (parent)
- parent->sd_count++;
- out:
- mutex_unlock(&genpd->lock);
- if (parent)
- genpd_release_lock(parent);
+ return 0;
+
+ err:
+ list_for_each_entry_continue_reverse(link, &genpd->slave_links, slave_node)
+ genpd_sd_counter_dec(link->master);
return ret;
}
+/**
+ * pm_genpd_poweron - Restore power to a given PM domain and its masters.
+ * @genpd: PM domain to power up.
+ */
+int pm_genpd_poweron(struct generic_pm_domain *genpd)
+{
+ int ret;
+
+ mutex_lock(&genpd->lock);
+ ret = __pm_genpd_poweron(genpd);
+ mutex_unlock(&genpd->lock);
+ return ret;
+}
+
#endif /* CONFIG_PM */
#ifdef CONFIG_PM_RUNTIME
/**
* __pm_genpd_save_device - Save the pre-suspend state of a device.
- * @dle: Device list entry of the device to save the state of.
+ * @pdd: Domain data of the device to save the state of.
* @genpd: PM domain the device belongs to.
*/
-static int __pm_genpd_save_device(struct dev_list_entry *dle,
+static int __pm_genpd_save_device(struct pm_domain_data *pdd,
struct generic_pm_domain *genpd)
__releases(&genpd->lock) __acquires(&genpd->lock)
{
- struct device *dev = dle->dev;
+ struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);
+ struct device *dev = pdd->dev;
struct device_driver *drv = dev->driver;
int ret = 0;
- if (dle->need_restore)
+ if (gpd_data->need_restore)
return 0;
mutex_unlock(&genpd->lock);
@@ -163,24 +211,25 @@ static int __pm_genpd_save_device(struct dev_list_entry *dle,
mutex_lock(&genpd->lock);
if (!ret)
- dle->need_restore = true;
+ gpd_data->need_restore = true;
return ret;
}
/**
* __pm_genpd_restore_device - Restore the pre-suspend state of a device.
- * @dle: Device list entry of the device to restore the state of.
+ * @pdd: Domain data of the device to restore the state of.
* @genpd: PM domain the device belongs to.
*/
-static void __pm_genpd_restore_device(struct dev_list_entry *dle,
+static void __pm_genpd_restore_device(struct pm_domain_data *pdd,
struct generic_pm_domain *genpd)
__releases(&genpd->lock) __acquires(&genpd->lock)
{
- struct device *dev = dle->dev;
+ struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);
+ struct device *dev = pdd->dev;
struct device_driver *drv = dev->driver;
- if (!dle->need_restore)
+ if (!gpd_data->need_restore)
return;
mutex_unlock(&genpd->lock);
@@ -197,7 +246,7 @@ static void __pm_genpd_restore_device(struct dev_list_entry *dle,
mutex_lock(&genpd->lock);
- dle->need_restore = false;
+ gpd_data->need_restore = false;
}
/**
@@ -211,7 +260,8 @@ static void __pm_genpd_restore_device(struct dev_list_entry *dle,
*/
static bool genpd_abort_poweroff(struct generic_pm_domain *genpd)
{
- return genpd->status == GPD_STATE_ACTIVE || genpd->resume_count > 0;
+ return genpd->status == GPD_STATE_WAIT_MASTER
+ || genpd->status == GPD_STATE_ACTIVE || genpd->resume_count > 0;
}
/**
@@ -238,8 +288,8 @@ void genpd_queue_power_off_work(struct generic_pm_domain *genpd)
static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
__releases(&genpd->lock) __acquires(&genpd->lock)
{
- struct generic_pm_domain *parent;
- struct dev_list_entry *dle;
+ struct pm_domain_data *pdd;
+ struct gpd_link *link;
unsigned int not_suspended;
int ret = 0;
@@ -247,19 +297,22 @@ static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
/*
* Do not try to power off the domain in the following situations:
* (1) The domain is already in the "power off" state.
- * (2) System suspend is in progress.
+ * (2) The domain is waiting for its master to power up.
* (3) One of the domain's devices is being resumed right now.
+ * (4) System suspend is in progress.
*/
- if (genpd->status == GPD_STATE_POWER_OFF || genpd->prepared_count > 0
- || genpd->resume_count > 0)
+ if (genpd->status == GPD_STATE_POWER_OFF
+ || genpd->status == GPD_STATE_WAIT_MASTER
+ || genpd->resume_count > 0 || genpd->prepared_count > 0)
return 0;
- if (genpd->sd_count > 0)
+ if (atomic_read(&genpd->sd_count) > 0)
return -EBUSY;
not_suspended = 0;
- list_for_each_entry(dle, &genpd->dev_list, node)
- if (dle->dev->driver && !pm_runtime_suspended(dle->dev))
+ list_for_each_entry(pdd, &genpd->dev_list, list_node)
+ if (pdd->dev->driver && (!pm_runtime_suspended(pdd->dev)
+ || pdd->dev->power.irq_safe))
not_suspended++;
if (not_suspended > genpd->in_progress)
@@ -282,54 +335,50 @@ static int pm_genpd_poweroff(struct generic_pm_domain *genpd)
genpd->status = GPD_STATE_BUSY;
genpd->poweroff_task = current;
- list_for_each_entry_reverse(dle, &genpd->dev_list, node) {
- ret = __pm_genpd_save_device(dle, genpd);
+ list_for_each_entry_reverse(pdd, &genpd->dev_list, list_node) {
+ ret = atomic_read(&genpd->sd_count) == 0 ?
+ __pm_genpd_save_device(pdd, genpd) : -EBUSY;
+
+ if (genpd_abort_poweroff(genpd))
+ goto out;
+
if (ret) {
genpd_set_active(genpd);
goto out;
}
- if (genpd_abort_poweroff(genpd))
- goto out;
-
if (genpd->status == GPD_STATE_REPEAT) {
genpd->poweroff_task = NULL;
goto start;
}
}
- parent = genpd->parent;
- if (parent) {
- mutex_unlock(&genpd->lock);
-
- genpd_acquire_lock(parent);
- mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);
-
- if (genpd_abort_poweroff(genpd)) {
- genpd_release_lock(parent);
+ if (genpd->power_off) {
+ if (atomic_read(&genpd->sd_count) > 0) {
+ ret = -EBUSY;
goto out;
}
- }
- if (genpd->power_off) {
+ /*
+ * If sd_count > 0 at this point, one of the subdomains hasn't
+ * managed to call pm_genpd_poweron() for the master yet after
+ * incrementing it. In that case pm_genpd_poweron() will wait
+ * for us to drop the lock, so we can call .power_off() and let
+ * the pm_genpd_poweron() restore power for us (this shouldn't
+ * happen very often).
+ */
ret = genpd->power_off(genpd);
if (ret == -EBUSY) {
genpd_set_active(genpd);
- if (parent)
- genpd_release_lock(parent);
-
goto out;
}
}
genpd->status = GPD_STATE_POWER_OFF;
- if (parent) {
- genpd_sd_counter_dec(parent);
- if (parent->sd_count == 0)
- genpd_queue_power_off_work(parent);
-
- genpd_release_lock(parent);
+ list_for_each_entry(link, &genpd->slave_links, slave_node) {
+ genpd_sd_counter_dec(link->master);
+ genpd_queue_power_off_work(link->master);
}
out:
@@ -371,12 +420,21 @@ static int pm_genpd_runtime_suspend(struct device *dev)
if (IS_ERR(genpd))
return -EINVAL;
+ might_sleep_if(!genpd->dev_irq_safe);
+
if (genpd->stop_device) {
int ret = genpd->stop_device(dev);
if (ret)
return ret;
}
+ /*
+ * If power.irq_safe is set, this routine will be run with interrupts
+ * off, so it can't use mutexes.
+ */
+ if (dev->power.irq_safe)
+ return 0;
+
mutex_lock(&genpd->lock);
genpd->in_progress++;
pm_genpd_poweroff(genpd);
@@ -387,24 +445,6 @@ static int pm_genpd_runtime_suspend(struct device *dev)
}
/**
- * __pm_genpd_runtime_resume - Resume a device belonging to I/O PM domain.
- * @dev: Device to resume.
- * @genpd: PM domain the device belongs to.
- */
-static void __pm_genpd_runtime_resume(struct device *dev,
- struct generic_pm_domain *genpd)
-{
- struct dev_list_entry *dle;
-
- list_for_each_entry(dle, &genpd->dev_list, node) {
- if (dle->dev == dev) {
- __pm_genpd_restore_device(dle, genpd);
- break;
- }
- }
-}
-
-/**
* pm_genpd_runtime_resume - Resume a device belonging to I/O PM domain.
* @dev: Device to resume.
*
@@ -424,11 +464,18 @@ static int pm_genpd_runtime_resume(struct device *dev)
if (IS_ERR(genpd))
return -EINVAL;
- ret = pm_genpd_poweron(genpd);
- if (ret)
- return ret;
+ might_sleep_if(!genpd->dev_irq_safe);
+
+ /* If power.irq_safe, the PM domain is never powered off. */
+ if (dev->power.irq_safe)
+ goto out;
mutex_lock(&genpd->lock);
+ ret = __pm_genpd_poweron(genpd);
+ if (ret) {
+ mutex_unlock(&genpd->lock);
+ return ret;
+ }
genpd->status = GPD_STATE_BUSY;
genpd->resume_count++;
for (;;) {
@@ -448,12 +495,13 @@ static int pm_genpd_runtime_resume(struct device *dev)
mutex_lock(&genpd->lock);
}
finish_wait(&genpd->status_wait_queue, &wait);
- __pm_genpd_runtime_resume(dev, genpd);
+ __pm_genpd_restore_device(dev->power.subsys_data->domain_data, genpd);
genpd->resume_count--;
genpd_set_active(genpd);
wake_up_all(&genpd->status_wait_queue);
mutex_unlock(&genpd->lock);
+ out:
if (genpd->start_device)
genpd->start_device(dev);
@@ -478,8 +526,6 @@ void pm_genpd_poweroff_unused(void)
#else
static inline void genpd_power_off_work_fn(struct work_struct *work) {}
-static inline void __pm_genpd_runtime_resume(struct device *dev,
- struct generic_pm_domain *genpd) {}
#define pm_genpd_runtime_suspend NULL
#define pm_genpd_runtime_resume NULL
@@ -489,11 +535,11 @@ static inline void __pm_genpd_runtime_resume(struct device *dev,
#ifdef CONFIG_PM_SLEEP
/**
- * pm_genpd_sync_poweroff - Synchronously power off a PM domain and its parents.
+ * pm_genpd_sync_poweroff - Synchronously power off a PM domain and its masters.
* @genpd: PM domain to power off, if possible.
*
* Check if the given PM domain can be powered off (during system suspend or
- * hibernation) and do that if so. Also, in that case propagate to its parent.
+ * hibernation) and do that if so. Also, in that case propagate to its masters.
*
* This function is only called in "noirq" stages of system power transitions,
* so it need not acquire locks (all of the "noirq" callbacks are executed
@@ -501,21 +547,23 @@ static inline void __pm_genpd_runtime_resume(struct device *dev,
*/
static void pm_genpd_sync_poweroff(struct generic_pm_domain *genpd)
{
- struct generic_pm_domain *parent = genpd->parent;
+ struct gpd_link *link;
if (genpd->status == GPD_STATE_POWER_OFF)
return;
- if (genpd->suspended_count != genpd->device_count || genpd->sd_count > 0)
+ if (genpd->suspended_count != genpd->device_count
+ || atomic_read(&genpd->sd_count) > 0)
return;
if (genpd->power_off)
genpd->power_off(genpd);
genpd->status = GPD_STATE_POWER_OFF;
- if (parent) {
- genpd_sd_counter_dec(parent);
- pm_genpd_sync_poweroff(parent);
+
+ list_for_each_entry(link, &genpd->slave_links, slave_node) {
+ genpd_sd_counter_dec(link->master);
+ pm_genpd_sync_poweroff(link->master);
}
}
@@ -666,7 +714,7 @@ static int pm_genpd_suspend_noirq(struct device *dev)
if (ret)
return ret;
- if (device_may_wakeup(dev)
+ if (dev->power.wakeup_path
&& genpd->active_wakeup && genpd->active_wakeup(dev))
return 0;
@@ -890,7 +938,7 @@ static int pm_genpd_dev_poweroff_noirq(struct device *dev)
if (ret)
return ret;
- if (device_may_wakeup(dev)
+ if (dev->power.wakeup_path
&& genpd->active_wakeup && genpd->active_wakeup(dev))
return 0;
@@ -1034,7 +1082,8 @@ static void pm_genpd_complete(struct device *dev)
*/
int pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
{
- struct dev_list_entry *dle;
+ struct generic_pm_domain_data *gpd_data;
+ struct pm_domain_data *pdd;
int ret = 0;
dev_dbg(dev, "%s()\n", __func__);
@@ -1054,26 +1103,26 @@ int pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
goto out;
}
- list_for_each_entry(dle, &genpd->dev_list, node)
- if (dle->dev == dev) {
+ list_for_each_entry(pdd, &genpd->dev_list, list_node)
+ if (pdd->dev == dev) {
ret = -EINVAL;
goto out;
}
- dle = kzalloc(sizeof(*dle), GFP_KERNEL);
- if (!dle) {
+ gpd_data = kzalloc(sizeof(*gpd_data), GFP_KERNEL);
+ if (!gpd_data) {
ret = -ENOMEM;
goto out;
}
- dle->dev = dev;
- dle->need_restore = false;
- list_add_tail(&dle->node, &genpd->dev_list);
genpd->device_count++;
- spin_lock_irq(&dev->power.lock);
dev->pm_domain = &genpd->domain;
- spin_unlock_irq(&dev->power.lock);
+ dev_pm_get_subsys_data(dev);
+ dev->power.subsys_data->domain_data = &gpd_data->base;
+ gpd_data->base.dev = dev;
+ gpd_data->need_restore = false;
+ list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
out:
genpd_release_lock(genpd);
@@ -1089,7 +1138,7 @@ int pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
int pm_genpd_remove_device(struct generic_pm_domain *genpd,
struct device *dev)
{
- struct dev_list_entry *dle;
+ struct pm_domain_data *pdd;
int ret = -EINVAL;
dev_dbg(dev, "%s()\n", __func__);
@@ -1104,17 +1153,17 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
goto out;
}
- list_for_each_entry(dle, &genpd->dev_list, node) {
- if (dle->dev != dev)
+ list_for_each_entry(pdd, &genpd->dev_list, list_node) {
+ if (pdd->dev != dev)
continue;
- spin_lock_irq(&dev->power.lock);
+ list_del_init(&pdd->list_node);
+ pdd->dev = NULL;
+ dev_pm_put_subsys_data(dev);
dev->pm_domain = NULL;
- spin_unlock_irq(&dev->power.lock);
+ kfree(to_gpd_data(pdd));
genpd->device_count--;
- list_del(&dle->node);
- kfree(dle);
ret = 0;
break;
@@ -1129,48 +1178,55 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
/**
* pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
* @genpd: Master PM domain to add the subdomain to.
- * @new_subdomain: Subdomain to be added.
+ * @subdomain: Subdomain to be added.
*/
int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
- struct generic_pm_domain *new_subdomain)
+ struct generic_pm_domain *subdomain)
{
- struct generic_pm_domain *subdomain;
+ struct gpd_link *link;
int ret = 0;
- if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(new_subdomain))
+ if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))
return -EINVAL;
start:
genpd_acquire_lock(genpd);
- mutex_lock_nested(&new_subdomain->lock, SINGLE_DEPTH_NESTING);
+ mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING);
- if (new_subdomain->status != GPD_STATE_POWER_OFF
- && new_subdomain->status != GPD_STATE_ACTIVE) {
- mutex_unlock(&new_subdomain->lock);
+ if (subdomain->status != GPD_STATE_POWER_OFF
+ && subdomain->status != GPD_STATE_ACTIVE) {
+ mutex_unlock(&subdomain->lock);
genpd_release_lock(genpd);
goto start;
}
if (genpd->status == GPD_STATE_POWER_OFF
- && new_subdomain->status != GPD_STATE_POWER_OFF) {
+ && subdomain->status != GPD_STATE_POWER_OFF) {
ret = -EINVAL;
goto out;
}
- list_for_each_entry(subdomain, &genpd->sd_list, sd_node) {
- if (subdomain == new_subdomain) {
+ list_for_each_entry(link, &genpd->slave_links, slave_node) {
+ if (link->slave == subdomain && link->master == genpd) {
ret = -EINVAL;
goto out;
}
}
- list_add_tail(&new_subdomain->sd_node, &genpd->sd_list);
- new_subdomain->parent = genpd;
+ link = kzalloc(sizeof(*link), GFP_KERNEL);
+ if (!link) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ link->master = genpd;
+ list_add_tail(&link->master_node, &genpd->master_links);
+ link->slave = subdomain;
+ list_add_tail(&link->slave_node, &subdomain->slave_links);
if (subdomain->status != GPD_STATE_POWER_OFF)
- genpd->sd_count++;
+ genpd_sd_counter_inc(genpd);
out:
- mutex_unlock(&new_subdomain->lock);
+ mutex_unlock(&subdomain->lock);
genpd_release_lock(genpd);
return ret;
@@ -1179,22 +1235,22 @@ int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
/**
* pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
* @genpd: Master PM domain to remove the subdomain from.
- * @target: Subdomain to be removed.
+ * @subdomain: Subdomain to be removed.
*/
int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
- struct generic_pm_domain *target)
+ struct generic_pm_domain *subdomain)
{
- struct generic_pm_domain *subdomain;
+ struct gpd_link *link;
int ret = -EINVAL;
- if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(target))
+ if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))
return -EINVAL;
start:
genpd_acquire_lock(genpd);
- list_for_each_entry(subdomain, &genpd->sd_list, sd_node) {
- if (subdomain != target)
+ list_for_each_entry(link, &genpd->master_links, master_node) {
+ if (link->slave != subdomain)
continue;
mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING);
@@ -1206,8 +1262,9 @@ int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
goto start;
}
- list_del(&subdomain->sd_node);
- subdomain->parent = NULL;
+ list_del(&link->master_node);
+ list_del(&link->slave_node);
+ kfree(link);
if (subdomain->status != GPD_STATE_POWER_OFF)
genpd_sd_counter_dec(genpd);
@@ -1234,15 +1291,14 @@ void pm_genpd_init(struct generic_pm_domain *genpd,
if (IS_ERR_OR_NULL(genpd))
return;
- INIT_LIST_HEAD(&genpd->sd_node);
- genpd->parent = NULL;
+ INIT_LIST_HEAD(&genpd->master_links);
+ INIT_LIST_HEAD(&genpd->slave_links);
INIT_LIST_HEAD(&genpd->dev_list);
- INIT_LIST_HEAD(&genpd->sd_list);
mutex_init(&genpd->lock);
genpd->gov = gov;
INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
genpd->in_progress = 0;
- genpd->sd_count = 0;
+ atomic_set(&genpd->sd_count, 0);
genpd->status = is_off ? GPD_STATE_POWER_OFF : GPD_STATE_ACTIVE;
init_waitqueue_head(&genpd->status_wait_queue);
genpd->poweroff_task = NULL;
diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
index a85459126bc6..59f8ab235486 100644
--- a/drivers/base/power/main.c
+++ b/drivers/base/power/main.c
@@ -46,6 +46,7 @@ LIST_HEAD(dpm_prepared_list);
LIST_HEAD(dpm_suspended_list);
LIST_HEAD(dpm_noirq_list);
+struct suspend_stats suspend_stats;
static DEFINE_MUTEX(dpm_list_mtx);
static pm_message_t pm_transition;
@@ -65,6 +66,7 @@ void device_pm_init(struct device *dev)
spin_lock_init(&dev->power.lock);
pm_runtime_init(dev);
INIT_LIST_HEAD(&dev->power.entry);
+ dev->power.power_state = PMSG_INVALID;
}
/**
@@ -96,6 +98,7 @@ void device_pm_add(struct device *dev)
dev_warn(dev, "parent %s should not be sleeping\n",
dev_name(dev->parent));
list_add_tail(&dev->power.entry, &dpm_list);
+ dev_pm_qos_constraints_init(dev);
mutex_unlock(&dpm_list_mtx);
}
@@ -109,6 +112,7 @@ void device_pm_remove(struct device *dev)
dev->bus ? dev->bus->name : "No Bus", dev_name(dev));
complete_all(&dev->power.completion);
mutex_lock(&dpm_list_mtx);
+ dev_pm_qos_constraints_destroy(dev);
list_del_init(&dev->power.entry);
mutex_unlock(&dpm_list_mtx);
device_wakeup_disable(dev);
@@ -464,8 +468,12 @@ void dpm_resume_noirq(pm_message_t state)
mutex_unlock(&dpm_list_mtx);
error = device_resume_noirq(dev, state);
- if (error)
+ if (error) {
+ suspend_stats.failed_resume_noirq++;
+ dpm_save_failed_step(SUSPEND_RESUME_NOIRQ);
+ dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, " early", error);
+ }
mutex_lock(&dpm_list_mtx);
put_device(dev);
@@ -626,8 +634,12 @@ void dpm_resume(pm_message_t state)
mutex_unlock(&dpm_list_mtx);
error = device_resume(dev, state, false);
- if (error)
+ if (error) {
+ suspend_stats.failed_resume++;
+ dpm_save_failed_step(SUSPEND_RESUME);
+ dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, state, "", error);
+ }
mutex_lock(&dpm_list_mtx);
}
@@ -802,6 +814,9 @@ int dpm_suspend_noirq(pm_message_t state)
mutex_lock(&dpm_list_mtx);
if (error) {
pm_dev_err(dev, state, " late", error);
+ suspend_stats.failed_suspend_noirq++;
+ dpm_save_failed_step(SUSPEND_SUSPEND_NOIRQ);
+ dpm_save_failed_dev(dev_name(dev));
put_device(dev);
break;
}
@@ -902,7 +917,11 @@ static int __device_suspend(struct device *dev, pm_message_t state, bool async)
}
End:
- dev->power.is_suspended = !error;
+ if (!error) {
+ dev->power.is_suspended = true;
+ if (dev->power.wakeup_path && dev->parent)
+ dev->parent->power.wakeup_path = true;
+ }
device_unlock(dev);
complete_all(&dev->power.completion);
@@ -923,8 +942,10 @@ static void async_suspend(void *data, async_cookie_t cookie)
int error;
error = __device_suspend(dev, pm_transition, true);
- if (error)
+ if (error) {
+ dpm_save_failed_dev(dev_name(dev));
pm_dev_err(dev, pm_transition, " async", error);
+ }
put_device(dev);
}
@@ -967,6 +988,7 @@ int dpm_suspend(pm_message_t state)
mutex_lock(&dpm_list_mtx);
if (error) {
pm_dev_err(dev, state, "", error);
+ dpm_save_failed_dev(dev_name(dev));
put_device(dev);
break;
}
@@ -980,7 +1002,10 @@ int dpm_suspend(pm_message_t state)
async_synchronize_full();
if (!error)
error = async_error;
- if (!error)
+ if (error) {
+ suspend_stats.failed_suspend++;
+ dpm_save_failed_step(SUSPEND_SUSPEND);
+ } else
dpm_show_time(starttime, state, NULL);
return error;
}
@@ -999,6 +1024,8 @@ static int device_prepare(struct device *dev, pm_message_t state)
device_lock(dev);
+ dev->power.wakeup_path = device_may_wakeup(dev);
+
if (dev->pm_domain) {
pm_dev_dbg(dev, state, "preparing power domain ");
if (dev->pm_domain->ops.prepare)
@@ -1088,7 +1115,10 @@ int dpm_suspend_start(pm_message_t state)
int error;
error = dpm_prepare(state);
- if (!error)
+ if (error) {
+ suspend_stats.failed_prepare++;
+ dpm_save_failed_step(SUSPEND_PREPARE);
+ } else
error = dpm_suspend(state);
return error;
}
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index b23de185cb04..434a6c011675 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -73,6 +73,7 @@ struct opp {
* RCU usage: nodes are not modified in the list of device_opp,
* however addition is possible and is secured by dev_opp_list_lock
* @dev: device pointer
+ * @head: notifier head to notify the OPP availability changes.
* @opp_list: list of opps
*
* This is an internal data structure maintaining the link to opps attached to
@@ -83,6 +84,7 @@ struct device_opp {
struct list_head node;
struct device *dev;
+ struct srcu_notifier_head head;
struct list_head opp_list;
};
@@ -404,6 +406,7 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
}
dev_opp->dev = dev;
+ srcu_init_notifier_head(&dev_opp->head);
INIT_LIST_HEAD(&dev_opp->opp_list);
/* Secure the device list modification */
@@ -428,6 +431,11 @@ int opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
list_add_rcu(&new_opp->node, head);
mutex_unlock(&dev_opp_list_lock);
+ /*
+ * Notify the changes in the availability of the operable
+ * frequency/voltage list.
+ */
+ srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ADD, new_opp);
return 0;
}
@@ -504,6 +512,14 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
mutex_unlock(&dev_opp_list_lock);
synchronize_rcu();
+ /* Notify the change of the OPP availability */
+ if (availability_req)
+ srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_ENABLE,
+ new_opp);
+ else
+ srcu_notifier_call_chain(&dev_opp->head, OPP_EVENT_DISABLE,
+ new_opp);
+
/* clean up old opp */
new_opp = opp;
goto out;
@@ -643,3 +659,17 @@ void opp_free_cpufreq_table(struct device *dev,
*table = NULL;
}
#endif /* CONFIG_CPU_FREQ */
+
+/**
+ * opp_get_notifier() - find notifier_head of the device with opp
+ * @dev: device pointer used to lookup device OPPs.
+ */
+struct srcu_notifier_head *opp_get_notifier(struct device *dev)
+{
+ struct device_opp *dev_opp = find_device_opp(dev);
+
+ if (IS_ERR(dev_opp))
+ return ERR_PTR(PTR_ERR(dev_opp)); /* matching type */
+
+ return &dev_opp->head;
+}
diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index f2a25f18fde7..9bf62323aaf3 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h
@@ -1,3 +1,5 @@
+#include <linux/pm_qos.h>
+
#ifdef CONFIG_PM_RUNTIME
extern void pm_runtime_init(struct device *dev);
@@ -35,15 +37,21 @@ extern void device_pm_move_last(struct device *);
static inline void device_pm_init(struct device *dev)
{
spin_lock_init(&dev->power.lock);
+ dev->power.power_state = PMSG_INVALID;
pm_runtime_init(dev);
}
+static inline void device_pm_add(struct device *dev)
+{
+ dev_pm_qos_constraints_init(dev);
+}
+
static inline void device_pm_remove(struct device *dev)
{
+ dev_pm_qos_constraints_destroy(dev);
pm_runtime_remove(dev);
}
-static inline void device_pm_add(struct device *dev) {}
static inline void device_pm_move_before(struct device *deva,
struct device *devb) {}
static inline void device_pm_move_after(struct device *deva,
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
new file mode 100644
index 000000000000..91e061417382
--- /dev/null
+++ b/drivers/base/power/qos.c
@@ -0,0 +1,419 @@
+/*
+ * Devices PM QoS constraints management
+ *
+ * Copyright (C) 2011 Texas Instruments, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ *
+ * This module exposes the interface to kernel space for specifying
+ * per-device PM QoS dependencies. It provides infrastructure for registration
+ * of:
+ *
+ * Dependents on a QoS value : register requests
+ * Watchers of QoS value : get notified when target QoS value changes
+ *
+ * This QoS design is best effort based. Dependents register their QoS needs.
+ * Watchers register to keep track of the current QoS needs of the system.
+ * Watchers can register different types of notification callbacks:
+ * . a per-device notification callback using the dev_pm_qos_*_notifier API.
+ * The notification chain data is stored in the per-device constraint
+ * data struct.
+ * . a system-wide notification callback using the dev_pm_qos_*_global_notifier
+ * API. The notification chain data is stored in a static variable.
+ *
+ * Note about the per-device constraint data struct allocation:
+ * . The per-device constraints data struct ptr is tored into the device
+ * dev_pm_info.
+ * . To minimize the data usage by the per-device constraints, the data struct
+ * is only allocated at the first call to dev_pm_qos_add_request.
+ * . The data is later free'd when the device is removed from the system.
+ * . A global mutex protects the constraints users from the data being
+ * allocated and free'd.
+ */
+
+#include <linux/pm_qos.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+
+
+static DEFINE_MUTEX(dev_pm_qos_mtx);
+
+static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
+
+/**
+ * dev_pm_qos_read_value - Get PM QoS constraint for a given device.
+ * @dev: Device to get the PM QoS constraint value for.
+ */
+s32 dev_pm_qos_read_value(struct device *dev)
+{
+ struct pm_qos_constraints *c;
+ unsigned long flags;
+ s32 ret = 0;
+
+ spin_lock_irqsave(&dev->power.lock, flags);
+
+ c = dev->power.constraints;
+ if (c)
+ ret = pm_qos_read_value(c);
+
+ spin_unlock_irqrestore(&dev->power.lock, flags);
+
+ return ret;
+}
+
+/*
+ * apply_constraint
+ * @req: constraint request to apply
+ * @action: action to perform add/update/remove, of type enum pm_qos_req_action
+ * @value: defines the qos request
+ *
+ * Internal function to update the constraints list using the PM QoS core
+ * code and if needed call the per-device and the global notification
+ * callbacks
+ */
+static int apply_constraint(struct dev_pm_qos_request *req,
+ enum pm_qos_req_action action, int value)
+{
+ int ret, curr_value;
+
+ ret = pm_qos_update_target(req->dev->power.constraints,
+ &req->node, action, value);
+
+ if (ret) {
+ /* Call the global callbacks if needed */
+ curr_value = pm_qos_read_value(req->dev->power.constraints);
+ blocking_notifier_call_chain(&dev_pm_notifiers,
+ (unsigned long)curr_value,
+ req);
+ }
+
+ return ret;
+}
+
+/*
+ * dev_pm_qos_constraints_allocate
+ * @dev: device to allocate data for
+ *
+ * Called at the first call to add_request, for constraint data allocation
+ * Must be called with the dev_pm_qos_mtx mutex held
+ */
+static int dev_pm_qos_constraints_allocate(struct device *dev)
+{
+ struct pm_qos_constraints *c;
+ struct blocking_notifier_head *n;
+
+ c = kzalloc(sizeof(*c), GFP_KERNEL);
+ if (!c)
+ return -ENOMEM;
+
+ n = kzalloc(sizeof(*n), GFP_KERNEL);
+ if (!n) {
+ kfree(c);
+ return -ENOMEM;
+ }
+ BLOCKING_INIT_NOTIFIER_HEAD(n);
+
+ plist_head_init(&c->list);
+ c->target_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
+ c->default_value = PM_QOS_DEV_LAT_DEFAULT_VALUE;
+ c->type = PM_QOS_MIN;
+ c->notifiers = n;
+
+ spin_lock_irq(&dev->power.lock);
+ dev->power.constraints = c;
+ spin_unlock_irq(&dev->power.lock);
+
+ return 0;
+}
+
+/**
+ * dev_pm_qos_constraints_init - Initalize device's PM QoS constraints pointer.
+ * @dev: target device
+ *
+ * Called from the device PM subsystem during device insertion under
+ * device_pm_lock().
+ */
+void dev_pm_qos_constraints_init(struct device *dev)
+{
+ mutex_lock(&dev_pm_qos_mtx);
+ dev->power.constraints = NULL;
+ dev->power.power_state = PMSG_ON;
+ mutex_unlock(&dev_pm_qos_mtx);
+}
+
+/**
+ * dev_pm_qos_constraints_destroy
+ * @dev: target device
+ *
+ * Called from the device PM subsystem on device removal under device_pm_lock().
+ */
+void dev_pm_qos_constraints_destroy(struct device *dev)
+{
+ struct dev_pm_qos_request *req, *tmp;
+ struct pm_qos_constraints *c;
+
+ mutex_lock(&dev_pm_qos_mtx);
+
+ dev->power.power_state = PMSG_INVALID;
+ c = dev->power.constraints;
+ if (!c)
+ goto out;
+
+ /* Flush the constraints list for the device */
+ plist_for_each_entry_safe(req, tmp, &c->list, node) {
+ /*
+ * Update constraints list and call the notification
+ * callbacks if needed
+ */
+ apply_constraint(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);
+ memset(req, 0, sizeof(*req));
+ }
+
+ spin_lock_irq(&dev->power.lock);
+ dev->power.constraints = NULL;
+ spin_unlock_irq(&dev->power.lock);
+
+ kfree(c->notifiers);
+ kfree(c);
+
+ out:
+ mutex_unlock(&dev_pm_qos_mtx);
+}
+
+/**
+ * dev_pm_qos_add_request - inserts new qos request into the list
+ * @dev: target device for the constraint
+ * @req: pointer to a preallocated handle
+ * @value: defines the qos request
+ *
+ * This function inserts a new entry in the device constraints list of
+ * requested qos performance characteristics. It recomputes the aggregate
+ * QoS expectations of parameters and initializes the dev_pm_qos_request
+ * handle. Caller needs to save this handle for later use in updates and
+ * removal.
+ *
+ * Returns 1 if the aggregated constraint value has changed,
+ * 0 if the aggregated constraint value has not changed,
+ * -EINVAL in case of wrong parameters, -ENOMEM if there's not enough memory
+ * to allocate for data structures, -ENODEV if the device has just been removed
+ * from the system.
+ */
+int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
+ s32 value)
+{
+ int ret = 0;
+
+ if (!dev || !req) /*guard against callers passing in null */
+ return -EINVAL;
+
+ if (dev_pm_qos_request_active(req)) {
+ WARN(1, KERN_ERR "dev_pm_qos_add_request() called for already "
+ "added request\n");
+ return -EINVAL;
+ }
+
+ req->dev = dev;
+
+ mutex_lock(&dev_pm_qos_mtx);
+
+ if (!dev->power.constraints) {
+ if (dev->power.power_state.event == PM_EVENT_INVALID) {
+ /* The device has been removed from the system. */
+ req->dev = NULL;
+ ret = -ENODEV;
+ goto out;
+ } else {
+ /*
+ * Allocate the constraints data on the first call to
+ * add_request, i.e. only if the data is not already
+ * allocated and if the device has not been removed.
+ */
+ ret = dev_pm_qos_constraints_allocate(dev);
+ }
+ }
+
+ if (!ret)
+ ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
+
+ out:
+ mutex_unlock(&dev_pm_qos_mtx);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_request);
+
+/**
+ * dev_pm_qos_update_request - modifies an existing qos request
+ * @req : handle to list element holding a dev_pm_qos request to use
+ * @new_value: defines the qos request
+ *
+ * Updates an existing dev PM qos request along with updating the
+ * target value.
+ *
+ * Attempts are made to make this code callable on hot code paths.
+ *
+ * Returns 1 if the aggregated constraint value has changed,
+ * 0 if the aggregated constraint value has not changed,
+ * -EINVAL in case of wrong parameters, -ENODEV if the device has been
+ * removed from the system
+ */
+int dev_pm_qos_update_request(struct dev_pm_qos_request *req,
+ s32 new_value)
+{
+ int ret = 0;
+
+ if (!req) /*guard against callers passing in null */
+ return -EINVAL;
+
+ if (!dev_pm_qos_request_active(req)) {
+ WARN(1, KERN_ERR "dev_pm_qos_update_request() called for "
+ "unknown object\n");
+ return -EINVAL;
+ }
+
+ mutex_lock(&dev_pm_qos_mtx);
+
+ if (req->dev->power.constraints) {
+ if (new_value != req->node.prio)
+ ret = apply_constraint(req, PM_QOS_UPDATE_REQ,
+ new_value);
+ } else {
+ /* Return if the device has been removed */
+ ret = -ENODEV;
+ }
+
+ mutex_unlock(&dev_pm_qos_mtx);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_update_request);
+
+/**
+ * dev_pm_qos_remove_request - modifies an existing qos request
+ * @req: handle to request list element
+ *
+ * Will remove pm qos request from the list of constraints and
+ * recompute the current target value. Call this on slow code paths.
+ *
+ * Returns 1 if the aggregated constraint value has changed,
+ * 0 if the aggregated constraint value has not changed,
+ * -EINVAL in case of wrong parameters, -ENODEV if the device has been
+ * removed from the system
+ */
+int dev_pm_qos_remove_request(struct dev_pm_qos_request *req)
+{
+ int ret = 0;
+
+ if (!req) /*guard against callers passing in null */
+ return -EINVAL;
+
+ if (!dev_pm_qos_request_active(req)) {
+ WARN(1, KERN_ERR "dev_pm_qos_remove_request() called for "
+ "unknown object\n");
+ return -EINVAL;
+ }
+
+ mutex_lock(&dev_pm_qos_mtx);
+
+ if (req->dev->power.constraints) {
+ ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
+ PM_QOS_DEFAULT_VALUE);
+ memset(req, 0, sizeof(*req));
+ } else {
+ /* Return if the device has been removed */
+ ret = -ENODEV;
+ }
+
+ mutex_unlock(&dev_pm_qos_mtx);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_request);
+
+/**
+ * dev_pm_qos_add_notifier - sets notification entry for changes to target value
+ * of per-device PM QoS constraints
+ *
+ * @dev: target device for the constraint
+ * @notifier: notifier block managed by caller.
+ *
+ * Will register the notifier into a notification chain that gets called
+ * upon changes to the target value for the device.
+ */
+int dev_pm_qos_add_notifier(struct device *dev, struct notifier_block *notifier)
+{
+ int retval = 0;
+
+ mutex_lock(&dev_pm_qos_mtx);
+
+ /* Silently return if the constraints object is not present. */
+ if (dev->power.constraints)
+ retval = blocking_notifier_chain_register(
+ dev->power.constraints->notifiers,
+ notifier);
+
+ mutex_unlock(&dev_pm_qos_mtx);
+ return retval;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_notifier);
+
+/**
+ * dev_pm_qos_remove_notifier - deletes notification for changes to target value
+ * of per-device PM QoS constraints
+ *
+ * @dev: target device for the constraint
+ * @notifier: notifier block to be removed.
+ *
+ * Will remove the notifier from the notification chain that gets called
+ * upon changes to the target value.
+ */
+int dev_pm_qos_remove_notifier(struct device *dev,
+ struct notifier_block *notifier)
+{
+ int retval = 0;
+
+ mutex_lock(&dev_pm_qos_mtx);
+
+ /* Silently return if the constraints object is not present. */
+ if (dev->power.constraints)
+ retval = blocking_notifier_chain_unregister(
+ dev->power.constraints->notifiers,
+ notifier);
+
+ mutex_unlock(&dev_pm_qos_mtx);
+ return retval;
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
+
+/**
+ * dev_pm_qos_add_global_notifier - sets notification entry for changes to
+ * target value of the PM QoS constraints for any device
+ *
+ * @notifier: notifier block managed by caller.
+ *
+ * Will register the notifier into a notification chain that gets called
+ * upon changes to the target value for any device.
+ */
+int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
+{
+ return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
+
+/**
+ * dev_pm_qos_remove_global_notifier - deletes notification for changes to
+ * target value of PM QoS constraints for any device
+ *
+ * @notifier: notifier block to be removed.
+ *
+ * Will remove the notifier from the notification chain that gets called
+ * upon changes to the target value for any device.
+ */
+int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
+{
+ return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index acb3f83b8079..6bb3aafa85ed 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -9,6 +9,7 @@
#include <linux/sched.h>
#include <linux/pm_runtime.h>
+#include <trace/events/rpm.h>
#include "power.h"
static int rpm_resume(struct device *dev, int rpmflags);
@@ -155,6 +156,31 @@ static int rpm_check_suspend_allowed(struct device *dev)
}
/**
+ * __rpm_callback - Run a given runtime PM callback for a given device.
+ * @cb: Runtime PM callback to run.
+ * @dev: Device to run the callback for.
+ */
+static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
+ __releases(&dev->power.lock) __acquires(&dev->power.lock)
+{
+ int retval;
+
+ if (dev->power.irq_safe)
+ spin_unlock(&dev->power.lock);
+ else
+ spin_unlock_irq(&dev->power.lock);
+
+ retval = cb(dev);
+
+ if (dev->power.irq_safe)
+ spin_lock(&dev->power.lock);
+ else
+ spin_lock_irq(&dev->power.lock);
+
+ return retval;
+}
+
+/**
* rpm_idle - Notify device bus type if the device can be suspended.
* @dev: Device to notify the bus type about.
* @rpmflags: Flag bits.
@@ -171,6 +197,7 @@ static int rpm_idle(struct device *dev, int rpmflags)
int (*callback)(struct device *);
int retval;
+ trace_rpm_idle(dev, rpmflags);
retval = rpm_check_suspend_allowed(dev);
if (retval < 0)
; /* Conditions are wrong. */
@@ -225,24 +252,14 @@ static int rpm_idle(struct device *dev, int rpmflags)
else
callback = NULL;
- if (callback) {
- if (dev->power.irq_safe)
- spin_unlock(&dev->power.lock);
- else
- spin_unlock_irq(&dev->power.lock);
-
- callback(dev);
-
- if (dev->power.irq_safe)
- spin_lock(&dev->power.lock);
- else
- spin_lock_irq(&dev->power.lock);
- }
+ if (callback)
+ __rpm_callback(callback, dev);
dev->power.idle_notification = false;
wake_up_all(&dev->power.wait_queue);
out:
+ trace_rpm_return_int(dev, _THIS_IP_, retval);
return retval;
}
@@ -252,22 +269,14 @@ static int rpm_idle(struct device *dev, int rpmflags)
* @dev: Device to run the callback for.
*/
static int rpm_callback(int (*cb)(struct device *), struct device *dev)
- __releases(&dev->power.lock) __acquires(&dev->power.lock)
{
int retval;
if (!cb)
return -ENOSYS;
- if (dev->power.irq_safe) {
- retval = cb(dev);
- } else {
- spin_unlock_irq(&dev->power.lock);
-
- retval = cb(dev);
+ retval = __rpm_callback(cb, dev);
- spin_lock_irq(&dev->power.lock);
- }
dev->power.runtime_error = retval;
return retval != -EACCES ? retval : -EIO;
}
@@ -277,14 +286,16 @@ static int rpm_callback(int (*cb)(struct device *), struct device *dev)
* @dev: Device to suspend.
* @rpmflags: Flag bits.
*
- * Check if the device's runtime PM status allows it to be suspended. If
- * another suspend has been started earlier, either return immediately or wait
- * for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC flags. Cancel a
- * pending idle notification. If the RPM_ASYNC flag is set then queue a
- * suspend request; otherwise run the ->runtime_suspend() callback directly.
- * If a deferred resume was requested while the callback was running then carry
- * it out; otherwise send an idle notification for the device (if the suspend
- * failed) or for its parent (if the suspend succeeded).
+ * Check if the device's runtime PM status allows it to be suspended.
+ * Cancel a pending idle notification, autosuspend or suspend. If
+ * another suspend has been started earlier, either return immediately
+ * or wait for it to finish, depending on the RPM_NOWAIT and RPM_ASYNC
+ * flags. If the RPM_ASYNC flag is set then queue a suspend request;
+ * otherwise run the ->runtime_suspend() callback directly. When
+ * ->runtime_suspend succeeded, if a deferred resume was requested while
+ * the callback was running then carry it out, otherwise send an idle
+ * notification for its parent (if the suspend succeeded and both
+ * ignore_children of parent->power and irq_safe of dev->power are not set).
*
* This function must be called under dev->power.lock with interrupts disabled.
*/
@@ -295,7 +306,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
struct device *parent = NULL;
int retval;
- dev_dbg(dev, "%s flags 0x%x\n", __func__, rpmflags);
+ trace_rpm_suspend(dev, rpmflags);
repeat:
retval = rpm_check_suspend_allowed(dev);
@@ -347,6 +358,15 @@ static int rpm_suspend(struct device *dev, int rpmflags)
goto out;
}
+ if (dev->power.irq_safe) {
+ spin_unlock(&dev->power.lock);
+
+ cpu_relax();
+
+ spin_lock(&dev->power.lock);
+ goto repeat;
+ }
+
/* Wait for the other suspend running in parallel with us. */
for (;;) {
prepare_to_wait(&dev->power.wait_queue, &wait,
@@ -400,15 +420,16 @@ static int rpm_suspend(struct device *dev, int rpmflags)
dev->power.runtime_error = 0;
else
pm_runtime_cancel_pending(dev);
- } else {
+ wake_up_all(&dev->power.wait_queue);
+ goto out;
+ }
no_callback:
- __update_runtime_status(dev, RPM_SUSPENDED);
- pm_runtime_deactivate_timer(dev);
+ __update_runtime_status(dev, RPM_SUSPENDED);
+ pm_runtime_deactivate_timer(dev);
- if (dev->parent) {
- parent = dev->parent;
- atomic_add_unless(&parent->power.child_count, -1, 0);
- }
+ if (dev->parent) {
+ parent = dev->parent;
+ atomic_add_unless(&parent->power.child_count, -1, 0);
}
wake_up_all(&dev->power.wait_queue);
@@ -430,7 +451,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
}
out:
- dev_dbg(dev, "%s returns %d\n", __func__, retval);
+ trace_rpm_return_int(dev, _THIS_IP_, retval);
return retval;
}
@@ -459,7 +480,7 @@ static int rpm_resume(struct device *dev, int rpmflags)
struct device *parent = NULL;
int retval = 0;
- dev_dbg(dev, "%s flags 0x%x\n", __func__, rpmflags);
+ trace_rpm_resume(dev, rpmflags);
repeat:
if (dev->power.runtime_error)
@@ -496,6 +517,15 @@ static int rpm_resume(struct device *dev, int rpmflags)
goto out;
}
+ if (dev->power.irq_safe) {
+ spin_unlock(&dev->power.lock);
+
+ cpu_relax();
+
+ spin_lock(&dev->power.lock);
+ goto repeat;
+ }
+
/* Wait for the operation carried out in parallel with us. */
for (;;) {
prepare_to_wait(&dev->power.wait_queue, &wait,
@@ -615,7 +645,7 @@ static int rpm_resume(struct device *dev, int rpmflags)
spin_lock_irq(&dev->power.lock);
}
- dev_dbg(dev, "%s returns %d\n", __func__, retval);
+ trace_rpm_return_int(dev, _THIS_IP_, retval);
return retval;
}
@@ -732,13 +762,16 @@ EXPORT_SYMBOL_GPL(pm_schedule_suspend);
* return immediately if it is larger than zero. Then carry out an idle
* notification, either synchronous or asynchronous.
*
- * This routine may be called in atomic context if the RPM_ASYNC flag is set.
+ * This routine may be called in atomic context if the RPM_ASYNC flag is set,
+ * or if pm_runtime_irq_safe() has been called.
*/
int __pm_runtime_idle(struct device *dev, int rpmflags)
{
unsigned long flags;
int retval;
+ might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
+
if (rpmflags & RPM_GET_PUT) {
if (!atomic_dec_and_test(&dev->power.usage_count))
return 0;
@@ -761,13 +794,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_idle);
* return immediately if it is larger than zero. Then carry out a suspend,
* either synchronous or asynchronous.
*
- * This routine may be called in atomic context if the RPM_ASYNC flag is set.
+ * This routine may be called in atomic context if the RPM_ASYNC flag is set,
+ * or if pm_runtime_irq_safe() has been called.
*/
int __pm_runtime_suspend(struct device *dev, int rpmflags)
{
unsigned long flags;
int retval;
+ might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
+
if (rpmflags & RPM_GET_PUT) {
if (!atomic_dec_and_test(&dev->power.usage_count))
return 0;
@@ -789,13 +825,16 @@ EXPORT_SYMBOL_GPL(__pm_runtime_suspend);
* If the RPM_GET_PUT flag is set, increment the device's usage count. Then
* carry out a resume, either synchronous or asynchronous.
*
- * This routine may be called in atomic context if the RPM_ASYNC flag is set.
+ * This routine may be called in atomic context if the RPM_ASYNC flag is set,
+ * or if pm_runtime_irq_safe() has been called.
*/
int __pm_runtime_resume(struct device *dev, int rpmflags)
{
unsigned long flags;
int retval;
+ might_sleep_if(!(rpmflags & RPM_ASYNC) && !dev->power.irq_safe);
+
if (rpmflags & RPM_GET_PUT)
atomic_inc(&dev->power.usage_count);
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
index 84f7c7d5a098..14ee07e9cc43 100644
--- a/drivers/base/power/wakeup.c
+++ b/drivers/base/power/wakeup.c
@@ -276,7 +276,9 @@ EXPORT_SYMBOL_GPL(device_set_wakeup_capable);
*
* By default, most devices should leave wakeup disabled. The exceptions are
* devices that everyone expects to be wakeup sources: keyboards, power buttons,
- * possibly network interfaces, etc.
+ * possibly network interfaces, etc. Also, devices that don't generate their
+ * own wakeup requests but merely forward requests from one bus to another
+ * (like PCI bridges) should have wakeup enabled by default.
*/
int device_init_wakeup(struct device *dev, bool enable)
{