From baa8809f60971d10220dfe79248f54b2b265f003 Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Date: Sun, 30 Oct 2016 17:32:43 +0100
Subject: [PATCH] PM / runtime: Optimize the use of device links
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 <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/base/core.c | 20 +++++++++++++-------
drivers/base/power/runtime.c | 23 ++++++++++++++++++++---
include/linux/pm.h | 1 +
include/linux/pm_runtime.h | 4 ++++
4 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 876c62b124627..d0c9df5cdd9ed 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -205,14 +205,17 @@ struct device_link *device_link_add(struct device *consumer,
if (!link)
goto out;
- if ((flags & DL_FLAG_PM_RUNTIME) && (flags & DL_FLAG_RPM_ACTIVE)) {
- if (pm_runtime_get_sync(supplier) < 0) {
- pm_runtime_put_noidle(supplier);
- kfree(link);
- link = NULL;
- goto out;
+ if (flags & DL_FLAG_PM_RUNTIME) {
+ if (flags & DL_FLAG_RPM_ACTIVE) {
+ if (pm_runtime_get_sync(supplier) < 0) {
+ pm_runtime_put_noidle(supplier);
+ kfree(link);
+ link = NULL;
+ goto out;
+ }
+ link->rpm_active = true;
}
- link->rpm_active = true;
+ pm_runtime_new_link(consumer);
}
get_device(supplier);
link->supplier = supplier;
@@ -296,6 +299,9 @@ static void __device_link_del(struct device_link *link)
dev_info(link->consumer, "Dropping the link to %s\n",
dev_name(link->supplier));
+ if (link->flags & DL_FLAG_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, __device_link_free_srcu);
diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index 462f90e952f84..ba7b4a8c07e5e 100644
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -305,6 +305,7 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
int retval, idx;
+ bool use_links = dev->power.links_count > 0;
if (dev->power.irq_safe) {
spin_unlock(&dev->power.lock);
@@ -318,7 +319,7 @@ 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();
retval = rpm_get_suppliers(dev);
@@ -341,8 +342,9 @@ 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:
@@ -1593,6 +1595,21 @@ void pm_runtime_put_suppliers(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 721a70241fcdc..ccfe00ecc7e64 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -597,6 +597,7 @@ 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 c2ee87138e4af..73814877537dd 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -58,6 +58,8 @@ 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_get_suppliers(struct device *dev);
extern void pm_runtime_put_suppliers(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)
{
@@ -192,6 +194,8 @@ static inline void pm_runtime_set_memalloc_noio(struct device *dev,
static inline void pm_runtime_clean_up_links(struct device *dev) {}
static inline void pm_runtime_get_suppliers(struct device *dev) {}
static inline void pm_runtime_put_suppliers(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 */
--
2.30.2