Parent devices might need to create "proxy" device links from themselves
to supplier devices to make sure the supplier devices don't get a
sync_state() before the child consumer devices get a chance to add
device links to the supplier devices.
However, the parent device has no real dependency on the supplier device
and probing, suspend/resume or runtime PM don't need to be affected by
the supplier device. To capture these cases, create a SYNC_STATE_ONLY
device link flag that only affects sync_state() behavior and doesn't
affect probing, suspend/resume or runtime PM.
Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx>
---
drivers/base/core.c | 50 ++++++++++++++++++++++++++++++++++--------
include/linux/device.h | 2 ++
2 files changed, 43 insertions(+), 9 deletions(-)
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 7ea665a97da2..17ed054c4132 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -131,6 +131,9 @@ static int device_is_dependent(struct device *dev, void *target)
return ret;
list_for_each_entry(link, &dev->links.consumers, s_node) {
+ if (link->flags == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
+ continue;
+
if (link->consumer == target)
return 1;
@@ -200,8 +203,11 @@ static int device_reorder_to_tail(struct device *dev, void *not_used)
device_pm_move_last(dev);
device_for_each_child(dev, NULL, device_reorder_to_tail);
- list_for_each_entry(link, &dev->links.consumers, s_node)
+ list_for_each_entry(link, &dev->links.consumers, s_node) {
+ if (link->flags == (DL_FLAG_SYNC_STATE_ONLY | DL_FLAG_MANAGED))
+ continue;
device_reorder_to_tail(link->consumer, NULL);
+ }
return 0;
}
@@ -228,7 +234,8 @@ void device_pm_move_to_tail(struct device *dev)
#define DL_MANAGED_LINK_FLAGS (DL_FLAG_AUTOREMOVE_CONSUMER | \
DL_FLAG_AUTOREMOVE_SUPPLIER | \
- DL_FLAG_AUTOPROBE_CONSUMER)
+ DL_FLAG_AUTOPROBE_CONSUMER | \
+ DL_FLAG_SYNC_STATE_ONLY)
#define DL_ADD_VALID_FLAGS (DL_MANAGED_LINK_FLAGS | DL_FLAG_STATELESS | \
DL_FLAG_PM_RUNTIME | DL_FLAG_RPM_ACTIVE)
@@ -296,6 +303,8 @@ struct device_link *device_link_add(struct device *consumer,
if (!consumer || !supplier || flags & ~DL_ADD_VALID_FLAGS ||
(flags & DL_FLAG_STATELESS && flags & DL_MANAGED_LINK_FLAGS) ||
+ (flags & DL_FLAG_SYNC_STATE_ONLY &&
+ flags != DL_FLAG_SYNC_STATE_ONLY) ||
(flags & DL_FLAG_AUTOPROBE_CONSUMER &&
flags & (DL_FLAG_AUTOREMOVE_CONSUMER |
DL_FLAG_AUTOREMOVE_SUPPLIER)))
@@ -316,11 +325,14 @@ struct device_link *device_link_add(struct device *consumer,
/*
* If the supplier has not been fully registered yet or there is a
- * reverse dependency between the consumer and the supplier already in
- * the graph, return NULL.
+ * reverse (non-SYNC_STATE_ONLY) dependency between the consumer and
+ * the supplier already in the graph, return NULL. If the link is a
+ * SYNC_STATE_ONLY link, we don't check for reverse dependencies
+ * because it only affects sync_state() callbacks.
*/
if (!device_pm_initialized(supplier)
- || device_is_dependent(consumer, supplier)) {
+ || (!(flags & DL_FLAG_SYNC_STATE_ONLY) &&
+ device_is_dependent(consumer, supplier))) {
link = NULL;
goto out;
}
@@ -347,9 +359,14 @@ struct device_link *device_link_add(struct device *consumer,
}
if (flags & DL_FLAG_STATELESS) {
- link->flags |= DL_FLAG_STATELESS;
kref_get(&link->kref);
- goto out;
+ if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
+ !(link->flags & DL_FLAG_STATELESS)) {
+ link->flags |= DL_FLAG_STATELESS;
+ goto reorder;
+ } else {
+ goto out;
+ }
}
/*
@@ -371,6 +388,12 @@ struct device_link *device_link_add(struct device *consumer,
link->flags |= DL_FLAG_MANAGED;
device_link_init_status(link, consumer, supplier);
}
+ if (link->flags & DL_FLAG_SYNC_STATE_ONLY &&
+ !(flags & DL_FLAG_SYNC_STATE_ONLY)) {
+ link->flags &= ~DL_FLAG_SYNC_STATE_ONLY;
+ goto reorder;
+ }
+
goto out;
}
@@ -410,6 +433,13 @@ struct device_link *device_link_add(struct device *consumer,
flags & DL_FLAG_PM_RUNTIME)
pm_runtime_resume(supplier);
+ if (flags & DL_FLAG_SYNC_STATE_ONLY) {
+ dev_dbg(consumer,
+ "Linked as a sync state only consumer to %s\n",
+ dev_name(supplier));
+ goto out;
+ }
+reorder:
/*
* Move the consumer and all of the devices depending on it to the end
* of dpm_list and the devices_kset list.
@@ -635,7 +665,8 @@ int device_links_check_suppliers(struct device *dev)
device_links_write_lock();
list_for_each_entry(link, &dev->links.suppliers, c_node) {
- if (!(link->flags & DL_FLAG_MANAGED))
+ if (!(link->flags & DL_FLAG_MANAGED) ||
+ link->flags & DL_FLAG_SYNC_STATE_ONLY)
continue;
if (link->status != DL_STATE_AVAILABLE) {
@@ -949,7 +980,8 @@ void device_links_unbind_consumers(struct device *dev)
list_for_each_entry(link, &dev->links.consumers, s_node) {
enum device_link_state status;
- if (!(link->flags & DL_FLAG_MANAGED))
+ if (!(link->flags & DL_FLAG_MANAGED) ||
+ link->flags & DL_FLAG_SYNC_STATE_ONLY)
continue;
status = link->status;
diff --git a/include/linux/device.h b/include/linux/device.h
index 9f2f2e169f95..f1f2aa0b19da 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1097,6 +1097,7 @@ enum device_link_state {
* AUTOREMOVE_SUPPLIER: Remove the link automatically on supplier driver unbind.
* AUTOPROBE_CONSUMER: Probe consumer driver automatically after supplier binds.
* MANAGED: The core tracks presence of supplier/consumer drivers (internal).
+ * SYNC_STATE_ONLY: Link only affects sync_state() behavior.
*/
#define DL_FLAG_STATELESS BIT(0)
#define DL_FLAG_AUTOREMOVE_CONSUMER BIT(1)
@@ -1105,6 +1106,7 @@ enum device_link_state {
#define DL_FLAG_AUTOREMOVE_SUPPLIER BIT(4)
#define DL_FLAG_AUTOPROBE_CONSUMER BIT(5)
#define DL_FLAG_MANAGED BIT(6)
+#define DL_FLAG_SYNC_STATE_ONLY BIT(7)
/**
* struct device_link - Device link representation.
--
2.24.0.rc0.303.g954a862665-goog
