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driver core: Allow a device to wait on optional suppliers 

Before this change, if a device is waiting on suppliers, it's assumed
that all those suppliers are needed for the device to probe
successfully. This change allows marking a devices as waiting only on
optional suppliers. This allows a device to wait on suppliers (and link
to them as soon as they are available) without preventing the device
from being probed.

Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20191028220027.251605-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Saravana Kannan 2019-10-28 15:00:23 -07:00 committed by Greg Kroah-Hartman
parent 05ef983e0d
commit bcbbcfd572
2 changed files with 28 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
drivers/base/core.c
View File

@ -480,13 +480,25 @@ EXPORT_SYMBOL_GPL(device_link_add);
* This function is NOT meant to be called from the probe function of the
* consumer but rather from code that creates/adds the consumer device.
*/
static void device_link_wait_for_supplier(struct device *consumer)
static void device_link_wait_for_supplier(struct device *consumer,
bool need_for_probe)
{
mutex_lock(&wfs_lock);
list_add_tail(&consumer->links.needs_suppliers, &wait_for_suppliers);
consumer->links.need_for_probe = need_for_probe;
mutex_unlock(&wfs_lock);
}
static void device_link_wait_for_mandatory_supplier(struct device *consumer)
{
device_link_wait_for_supplier(consumer, true);
}
static void device_link_wait_for_optional_supplier(struct device *consumer)
{
device_link_wait_for_supplier(consumer, false);
}
/**
* device_link_add_missing_supplier_links - Add links from consumer devices to
* supplier devices, leaving any
@ -656,7 +668,8 @@ int device_links_check_suppliers(struct device *dev)
* probe.
*/
mutex_lock(&wfs_lock);
if (!list_empty(&dev->links.needs_suppliers)) {
if (!list_empty(&dev->links.needs_suppliers) &&
dev->links.need_for_probe) {
mutex_unlock(&wfs_lock);
return -EPROBE_DEFER;
}
@ -760,6 +773,15 @@ void device_links_driver_bound(struct device *dev)
{
struct device_link *link;
/*
* If a device probes successfully, it's expected to have created all
* the device links it needs to or make new device links as it needs
* them. So, it no longer needs to wait on any suppliers.
*/
mutex_lock(&wfs_lock);
list_del_init(&dev->links.needs_suppliers);
mutex_unlock(&wfs_lock);
device_links_write_lock();
list_for_each_entry(link, &dev->links.consumers, s_node) {
@ -2393,7 +2415,7 @@ int device_add(struct device *dev)
if (fwnode_has_op(dev->fwnode, add_links)
&& fwnode_call_int_op(dev->fwnode, add_links, dev))
device_link_wait_for_supplier(dev);
device_link_wait_for_mandatory_supplier(dev, true);
bus_probe_device(dev);
if (parent)

3
include/linux/device.h
View File

@ -1155,6 +1155,8 @@ enum dl_dev_state {
* @consumers: List of links to consumer devices.
* @needs_suppliers: Hook to global list of devices waiting for suppliers.
* @defer_sync: Hook to global list of devices that have deferred sync_state.
* @need_for_probe: If needs_suppliers is on a list, this indicates if the
* suppliers are needed for probe or not.
* @status: Driver status information.
*/
struct dev_links_info {
@ -1162,6 +1164,7 @@ struct dev_links_info {
struct list_head consumers;
struct list_head needs_suppliers;
struct list_head defer_sync;
bool need_for_probe;
enum dl_dev_state status;
};