From 05ef983e0d65a31b370a4e1b93c1efd490ae778f Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Mon, 28 Oct 2019 15:00:22 -0700 Subject: driver core: Add device link support for SYNC_STATE_ONLY flag 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 Link: https://lore.kernel.org/r/20191028220027.251605-2-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 50 +++++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 41 insertions(+), 9 deletions(-) (limited to 'drivers/base') 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; -- cgit v1.2.3-70-g09d2