[PATCH v2 05/10] PM core: Optimize the use of device links for runtime PM
From: m.szyprowski@samsung.com (Marek Szyprowski)
Date: 2016-06-17 06:27:22
Also in:
linux-iommu, linux-pm, linux-samsung-soc, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, hibernation (aka software suspend, aka swsusp), power management core, suspend to ram, the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Linus Torvalds
From: "Rafael J. Wysocki" <redacted> If the device has no links to suppliers that should be used for runtime PM (links with DEVICE_LINK_PM_RUNTIME set), there is no reason to walk the list of suppliers for that device during runtime suspend and resume. Add a simple mechanism to detect that case and possibly avoid the extra unnecessary overhead. Signed-off-by: Rafael J. Wysocki <redacted> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> --- drivers/base/core.c | 6 ++++++ drivers/base/power/runtime.c | 23 ++++++++++++++++++++--- include/linux/pm.h | 1 + include/linux/pm_runtime.h | 4 ++++ 4 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 1fe7cf232e1e..215cd44de761 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c@@ -119,6 +119,9 @@ struct devlink *device_link_add(struct device *consumer, get_device(consumer); link->consumer = consumer; INIT_LIST_HEAD(&link->c_node); + if (flags & DEVICE_LINK_PM_RUNTIME) + pm_runtime_new_link(consumer); + link->flags = flags; link->status = (flags & DEVICE_LINK_PROBE_TIME) ? DEVICE_LINK_CONSUMER_PROBE : DEVICE_LINK_DORMANT;
@@ -161,6 +164,9 @@ static void devlink_del(struct devlink *link) dev_info(link->consumer, "Dropping the link to %s\n", dev_name(link->supplier)); + if (link->flags & DEVICE_LINK_PM_RUNTIME) + pm_runtime_drop_link(link->consumer); + list_del_rcu(&link->s_node); list_del_rcu(&link->c_node); call_srcu(&device_links_srcu, &link->rcu_head, __devlink_free_srcu);
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index ba21c123b16e..0ea00d442e0f 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c@@ -270,6 +270,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) { struct devlink *link; int retval, idx; + bool use_links = dev->power.links_count > 0; if (dev->power.irq_safe) { spin_unlock(&dev->power.lock);
@@ -283,7 +284,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) * routine returns, so it is safe to read the status outside of * the lock. */ - if (dev->power.runtime_status == RPM_RESUMING) { + if (use_links && dev->power.runtime_status == RPM_RESUMING) { idx = device_links_read_lock(); list_for_each_entry_rcu(link, &dev->consumer_links, c_node)
@@ -314,8 +315,9 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev) * * Do that if resume fails too. */ - if ((dev->power.runtime_status == RPM_SUSPENDING && !retval) - || (dev->power.runtime_status == RPM_RESUMING && retval)) { + if (use_links + && ((dev->power.runtime_status == RPM_SUSPENDING && !retval) + || (dev->power.runtime_status == RPM_RESUMING && retval))) { idx = device_links_read_lock(); fail:
@@ -1525,6 +1527,21 @@ void pm_runtime_clean_up_links(struct device *dev) device_links_read_unlock(idx); } +void pm_runtime_new_link(struct device *dev) +{ + spin_lock_irq(&dev->power.lock); + dev->power.links_count++; + spin_unlock_irq(&dev->power.lock); +} + +void pm_runtime_drop_link(struct device *dev) +{ + spin_lock_irq(&dev->power.lock); + WARN_ON(dev->power.links_count == 0); + dev->power.links_count--; + spin_unlock_irq(&dev->power.lock); +} + /** * pm_runtime_force_suspend - Force a device into suspend state if needed. * @dev: Device to suspend.
diff --git a/include/linux/pm.h b/include/linux/pm.h
index 06eb353182ab..49c811378110 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h@@ -596,6 +596,7 @@ struct dev_pm_info { unsigned int use_autosuspend:1; unsigned int timer_autosuspends:1; unsigned int memalloc_noio:1; + unsigned int links_count; enum rpm_request request; enum rpm_status runtime_status; int runtime_error;
diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index c21a21c064e3..bef6203aaf14 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h@@ -56,6 +56,8 @@ extern void pm_runtime_update_max_time_suspended(struct device *dev, s64 delta_ns); extern void pm_runtime_set_memalloc_noio(struct device *dev, bool enable); extern void pm_runtime_clean_up_links(struct device *dev); +extern void pm_runtime_new_link(struct device *dev); +extern void pm_runtime_drop_link(struct device *dev); static inline void pm_suspend_ignore_children(struct device *dev, bool enable) {
@@ -188,6 +190,8 @@ static inline unsigned long pm_runtime_autosuspend_expiration( static inline void pm_runtime_set_memalloc_noio(struct device *dev, bool enable){} static inline void pm_runtime_clean_up_links(struct device *dev) {} +static inline void pm_runtime_new_link(struct device *dev) {} +static inline void pm_runtime_drop_link(struct device *dev) {} #endif /* !CONFIG_PM */
--
1.9.1