===================================================================
@@ -117,6 +117,14 @@ static int device_reorder_to_tail(struct
* @supplier: Supplier end of the link.
* @flags: Link flags.
*
+ * The caller is responsible for the proper synchronization of the link creation
+ * with runtime PM. First, setting the DL_FLAG_PM_RUNTIME flag will cause the
+ * runtime PM framework to take the link into account. Second, if the
+ * DL_FLAG_RPM_ACTIVE flag is set in addition to it, the supplier devices will
+ * be forced into the active metastate and reference-counted upon the creation
+ * of the link. If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
+ * ignored.
+ *
* If the DL_FLAG_AUTOREMOVE is set, the link will be removed automatically
* when the consumer device driver unbinds from it. The combination of both
* DL_FLAG_AUTOREMOVE and DL_FLAG_STATELESS set is invalid and will cause NULL
@@ -158,10 +166,19 @@ struct device_link *device_link_add(stru
if (link->consumer == consumer)
goto out;
- link = kmalloc(sizeof(*link), GFP_KERNEL);
+ link = kzalloc(sizeof(*link), GFP_KERNEL);
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;
+ }
+ link->rpm_active = true;
+ }
get_device(supplier);
link->supplier = supplier;
INIT_LIST_HEAD(&link->s_node);
===================================================================
@@ -498,6 +498,7 @@ int driver_probe_device(struct device_dr
pr_debug("bus: '%s': %s: matched device %s with driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);
+ pm_runtime_get_suppliers(dev);
if (dev->parent)
pm_runtime_get_sync(dev->parent);
@@ -508,6 +509,7 @@ int driver_probe_device(struct device_dr
if (dev->parent)
pm_runtime_put(dev->parent);
+ pm_runtime_put_suppliers(dev);
return ret;
}
@@ -791,6 +793,7 @@ static void __device_release_driver(stru
}
pm_runtime_get_sync(dev);
+ pm_runtime_clean_up_links(dev);
driver_sysfs_remove(dev);
===================================================================
@@ -12,6 +12,8 @@
#include <linux/pm_runtime.h>
#include <linux/pm_wakeirq.h>
#include <trace/events/rpm.h>
+
+#include "../base.h"
#include "power.h"
typedef int (*pm_callback_t)(struct device *);
@@ -258,6 +260,42 @@ static int rpm_check_suspend_allowed(str
return retval;
}
+static int rpm_get_suppliers(struct device *dev)
+{
+ struct device_link *link;
+
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node) {
+ int retval;
+
+ if (!(link->flags & DL_FLAG_PM_RUNTIME))
+ continue;
+
+ if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND ||
+ link->rpm_active)
+ continue;
+
+ retval = pm_runtime_get_sync(link->supplier);
+ if (retval < 0) {
+ pm_runtime_put_noidle(link->supplier);
+ return retval;
+ }
+ link->rpm_active = true;
+ }
+ return 0;
+}
+
+static void rpm_put_suppliers(struct device *dev)
+{
+ struct device_link *link;
+
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+ if (link->rpm_active &&
+ READ_ONCE(link->status) != DL_STATE_SUPPLIER_UNBIND) {
+ pm_runtime_put(link->supplier);
+ link->rpm_active = false;
+ }
+}
+
/**
* __rpm_callback - Run a given runtime PM callback for a given device.
* @cb: Runtime PM callback to run.
@@ -266,19 +304,55 @@ static int rpm_check_suspend_allowed(str
static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
__releases(&dev->power.lock) __acquires(&dev->power.lock)
{
- int retval;
+ int retval, idx;
- if (dev->power.irq_safe)
+ if (dev->power.irq_safe) {
spin_unlock(&dev->power.lock);
- else
+ } else {
spin_unlock_irq(&dev->power.lock);
+ /*
+ * Resume suppliers if necessary.
+ *
+ * The device's runtime PM status cannot change until this
+ * routine returns, so it is safe to read the status outside of
+ * the lock.
+ */
+ if (dev->power.runtime_status == RPM_RESUMING) {
+ idx = device_links_read_lock();
+
+ retval = rpm_get_suppliers(dev);
+ if (retval)
+ goto fail;
+
+ device_links_read_unlock(idx);
+ }
+ }
+
retval = cb(dev);
- if (dev->power.irq_safe)
+ if (dev->power.irq_safe) {
spin_lock(&dev->power.lock);
- else
+ } else {
+ /*
+ * If the device is suspending and the callback has returned
+ * success, drop the usage counters of the suppliers that have
+ * been reference counted on its resume.
+ *
+ * Do that if resume fails too.
+ */
+ if ((dev->power.runtime_status == RPM_SUSPENDING && !retval)
+ || (dev->power.runtime_status == RPM_RESUMING && retval)) {
+ idx = device_links_read_lock();
+
+ fail:
+ rpm_put_suppliers(dev);
+
+ device_links_read_unlock(idx);
+ }
+
spin_lock_irq(&dev->power.lock);
+ }
return retval;
}
@@ -1447,6 +1521,79 @@ void pm_runtime_remove(struct device *de
}
/**
+ * pm_runtime_clean_up_links - Prepare links to consumers for driver removal.
+ * @dev: Device whose driver is going to be removed.
+ *
+ * Check links from this device to any consumers and if any of them have active
+ * runtime PM references to the device, drop the usage counter of the device
+ * (once per link).
+ *
+ * Links with the DL_FLAG_STATELESS flag set are ignored.
+ *
+ * Since the device is guaranteed to be runtime-active at the point this is
+ * called, nothing else needs to be done here.
+ *
+ * Moreover, this is called after device_links_busy() has returned 'false', so
+ * the status of each link is guaranteed to be DL_STATE_SUPPLIER_UNBIND and
+ * therefore rpm_active can't be manipulated concurrently.
+ */
+void pm_runtime_clean_up_links(struct device *dev)
+{
+ struct device_link *link;
+ int idx;
+
+ idx = device_links_read_lock();
+
+ list_for_each_entry_rcu(link, &dev->links.consumers, s_node) {
+ if (link->flags & DL_FLAG_STATELESS)
+ continue;
+
+ if (link->rpm_active) {
+ pm_runtime_put_noidle(dev);
+ link->rpm_active = false;
+ }
+ }
+
+ device_links_read_unlock(idx);
+}
+
+/**
+ * pm_runtime_get_suppliers - Resume and reference-count supplier devices.
+ * @dev: Consumer device.
+ */
+void pm_runtime_get_suppliers(struct device *dev)
+{
+ struct device_link *link;
+ int idx;
+
+ idx = device_links_read_lock();
+
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+ if (link->flags & DL_FLAG_PM_RUNTIME)
+ pm_runtime_get_sync(link->supplier);
+
+ device_links_read_unlock(idx);
+}
+
+/**
+ * pm_runtime_put_suppliers - Drop references to supplier devices.
+ * @dev: Consumer device.
+ */
+void pm_runtime_put_suppliers(struct device *dev)
+{
+ struct device_link *link;
+ int idx;
+
+ idx = device_links_read_lock();
+
+ list_for_each_entry_rcu(link, &dev->links.suppliers, c_node)
+ if (link->flags & DL_FLAG_PM_RUNTIME)
+ pm_runtime_put(link->supplier);
+
+ device_links_read_unlock(idx);
+}
+
+/**
* pm_runtime_force_suspend - Force a device into suspend state if needed.
* @dev: Device to suspend.
*
===================================================================
@@ -729,9 +729,13 @@ enum device_link_state {
*
* STATELESS: The core won't track the presence of supplier/consumer drivers.
* AUTOREMOVE: Remove this link automatically on consumer driver unbind.
+ * PM_RUNTIME: If set, the runtime PM framework will use this link.
+ * RPM_ACTIVE: Run pm_runtime_get_sync() on the supplier during link creation.
*/
#define DL_FLAG_STATELESS (1 << 0)
#define DL_FLAG_AUTOREMOVE (1 << 1)
+#define DL_FLAG_PM_RUNTIME (1 << 2)
+#define DL_FLAG_RPM_ACTIVE (1 << 3)
/**
* struct device_link - Device link representation.
@@ -750,6 +754,7 @@ struct device_link {
struct list_head c_node;
enum device_link_state status;
u32 flags;
+ bool rpm_active;
struct rcu_head rcu_head;
};
===================================================================
@@ -55,6 +55,9 @@ extern unsigned long pm_runtime_autosusp
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_get_suppliers(struct device *dev);
+extern void pm_runtime_put_suppliers(struct device *dev);
static inline void pm_suspend_ignore_children(struct device *dev, bool enable)
{
@@ -186,6 +189,9 @@ static inline unsigned long pm_runtime_a
struct device *dev) { return 0; }
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_get_suppliers(struct device *dev) {}
+static inline void pm_runtime_put_suppliers(struct device *dev) {}
#endif /* !CONFIG_PM */