Merge tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the big driver core patchset for 5.1-rc1

  More patches than "normal" here this merge window, due to some work in
  the driver core by Alexander Duyck to rework the async probe
  functionality to work better for a number of devices, and independant
  work from Rafael for the device link functionality to make it work
  "correctly".

  Also in here is:

   - lots of BUS_ATTR() removals, the macro is about to go away

   - firmware test fixups

   - ihex fixups and simplification

   - component additions (also includes i915 patches)

   - lots of minor coding style fixups and cleanups.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'driver-core-5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (65 commits)
  driver core: platform: remove misleading err_alloc label
  platform: set of_node in platform_device_register_full()
  firmware: hardcode the debug message for -ENOENT
  driver core: Add missing description of new struct device_link field
  driver core: Fix PM-runtime for links added during consumer probe
  drivers/component: kerneldoc polish
  async: Add cmdline option to specify drivers to be async probed
  driver core: Fix possible supplier PM-usage counter imbalance
  PM-runtime: Fix __pm_runtime_set_status() race with runtime resume
  driver: platform: Support parsing GpioInt 0 in platform_get_irq()
  selftests: firmware: fix verify_reqs() return value
  Revert "selftests: firmware: remove use of non-standard diff -Z option"
  Revert "selftests: firmware: add CONFIG_FW_LOADER_USER_HELPER_FALLBACK to config"
  device: Fix comment for driver_data in struct device
  kernfs: Allocating memory for kernfs_iattrs with kmem_cache.
  sysfs: remove unused include of kernfs-internal.h
  driver core: Postpone DMA tear-down until after devres release
  driver core: Document limitation related to DL_FLAG_RPM_ACTIVE
  PM-runtime: Take suppliers into account in __pm_runtime_set_status()
  device.h: Add __cold to dev_<level> logging functions
  ...

52 files changed, 1095 insertions, 412 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a87418990d39..879afb4a1573 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -915,6 +915,10 @@
 			The filter can be disabled or changed to another
 			driver later using sysfs.
 
+	driver_async_probe=  [KNL]
+			List of driver names to be probed asynchronously.
+			Format: <driver_name1>,<driver_name2>...
+
 	drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
 			Broken monitors, graphic adapters, KVMs and EDIDless
 			panels may send no or incorrect EDID data sets.
diff --git a/Documentation/driver-api/device_link.rst b/Documentation/driver-api/device_link.rst
index 2d5919b2b337..ae1e3d0394b0 100644
--- a/Documentation/driver-api/device_link.rst
+++ b/Documentation/driver-api/device_link.rst
@@ -28,8 +28,8 @@ suspend/resume and shutdown ordering.
 
 Device links allow representation of such dependencies in the driver core.
 
-In its standard form, a device link combines *both* dependency types:
-It guarantees correct suspend/resume and shutdown ordering between a
+In its standard or *managed* form, a device link combines *both* dependency
+types:  It guarantees correct suspend/resume and shutdown ordering between a
 "supplier" device and its "consumer" devices, and it guarantees driver
 presence on the supplier.  The consumer devices are not probed before the
 supplier is bound to a driver, and they're unbound before the supplier
@@ -62,18 +62,24 @@ device ``->probe`` callback or a boot-time PCI quirk.
 
 Another example for an inconsistent state would be a device link that
 represents a driver presence dependency, yet is added from the consumer's
-``->probe`` callback while the supplier hasn't probed yet:  Had the driver
-core known about the device link earlier, it wouldn't have probed the
+``->probe`` callback while the supplier hasn't started to probe yet:  Had the
+driver core known about the device link earlier, it wouldn't have probed the
 consumer in the first place.  The onus is thus on the consumer to check
 presence of the supplier after adding the link, and defer probing on
-non-presence.
-
-If a device link is added in the ``->probe`` callback of the supplier or
-consumer driver, it is typically deleted in its ``->remove`` callback for
-symmetry.  That way, if the driver is compiled as a module, the device
-link is added on module load and orderly deleted on unload.  The same
-restrictions that apply to device link addition (e.g. exclusion of a
-parallel suspend/resume transition) apply equally to deletion.
+non-presence.  [Note that it is valid to create a link from the consumer's
+``->probe`` callback while the supplier is still probing, but the consumer must
+know that the supplier is functional already at the link creation time (that is
+the case, for instance, if the consumer has just acquired some resources that
+would not have been available had the supplier not been functional then).]
+
+If a device link with ``DL_FLAG_STATELESS`` set (i.e. a stateless device link)
+is added in the ``->probe`` callback of the supplier or consumer driver, it is
+typically deleted in its ``->remove`` callback for symmetry.  That way, if the
+driver is compiled as a module, the device link is added on module load and
+orderly deleted on unload.  The same restrictions that apply to device link
+addition (e.g. exclusion of a parallel suspend/resume transition) apply equally
+to deletion.  Device links with ``DL_FLAG_STATELESS`` unset (i.e. managed
+device links) are deleted automatically by the driver core.
 
 Several flags may be specified on device link addition, two of which
 have already been mentioned above:  ``DL_FLAG_STATELESS`` to express that no
@@ -83,25 +89,55 @@ integration is desired.
 
 Two other flags are specifically targeted at use cases where the device
 link is added from the consumer's ``->probe`` callback:  ``DL_FLAG_RPM_ACTIVE``
-can be specified to runtime resume the supplier upon addition of the
-device link.  ``DL_FLAG_AUTOREMOVE_CONSUMER`` causes the device link to be
-automatically purged when the consumer fails to probe or later unbinds.
-This obviates the need to explicitly delete the link in the ``->remove``
-callback or in the error path of the ``->probe`` callback.
+can be specified to runtime resume the supplier and prevent it from suspending
+before the consumer is runtime suspended.  ``DL_FLAG_AUTOREMOVE_CONSUMER``
+causes the device link to be automatically purged when the consumer fails to
+probe or later unbinds.
 
 Similarly, when the device link is added from supplier's ``->probe`` callback,
 ``DL_FLAG_AUTOREMOVE_SUPPLIER`` causes the device link to be automatically
 purged when the supplier fails to probe or later unbinds.
 
+If neither ``DL_FLAG_AUTOREMOVE_CONSUMER`` nor ``DL_FLAG_AUTOREMOVE_SUPPLIER``
+is set, ``DL_FLAG_AUTOPROBE_CONSUMER`` can be used to request the driver core
+to probe for a driver for the consumer driver on the link automatically after
+a driver has been bound to the supplier device.
+
+Note, however, that any combinations of ``DL_FLAG_AUTOREMOVE_CONSUMER``,
+``DL_FLAG_AUTOREMOVE_SUPPLIER`` or ``DL_FLAG_AUTOPROBE_CONSUMER`` with
+``DL_FLAG_STATELESS`` are invalid and cannot be used.
+
 Limitations
 ===========
 
-Driver authors should be aware that a driver presence dependency (i.e. when
-``DL_FLAG_STATELESS`` is not specified on link addition) may cause probing of
-the consumer to be deferred indefinitely.  This can become a problem if the
-consumer is required to probe before a certain initcall level is reached.
-Worse, if the supplier driver is blacklisted or missing, the consumer will
-never be probed.
+Driver authors should be aware that a driver presence dependency for managed
+device links (i.e. when ``DL_FLAG_STATELESS`` is not specified on link addition)
+may cause probing of the consumer to be deferred indefinitely.  This can become
+a problem if the consumer is required to probe before a certain initcall level
+is reached.  Worse, if the supplier driver is blacklisted or missing, the
+consumer will never be probed.
+
+Moreover, managed device links cannot be deleted directly.  They are deleted
+by the driver core when they are not necessary any more in accordance with the
+``DL_FLAG_AUTOREMOVE_CONSUMER`` and ``DL_FLAG_AUTOREMOVE_SUPPLIER`` flags.
+However, stateless device links (i.e. device links with ``DL_FLAG_STATELESS``
+set) are expected to be removed by whoever called :c:func:`device_link_add()`
+to add them with the help of either :c:func:`device_link_del()` or
+:c:func:`device_link_remove()`.
+
+Passing ``DL_FLAG_RPM_ACTIVE`` along with ``DL_FLAG_STATELESS`` to
+:c:func:`device_link_add()` may cause the PM-runtime usage counter of the
+supplier device to remain nonzero after a subsequent invocation of either
+:c:func:`device_link_del()` or :c:func:`device_link_remove()` to remove the
+device link returned by it.  This happens if :c:func:`device_link_add()` is
+called twice in a row for the same consumer-supplier pair without removing the
+link between these calls, in which case allowing the PM-runtime usage counter
+of the supplier to drop on an attempt to remove the link may cause it to be
+suspended while the consumer is still PM-runtime-active and that has to be
+avoided.  [To work around this limitation it is sufficient to let the consumer
+runtime suspend at least once, or call :c:func:`pm_runtime_set_suspended()` for
+it with PM-runtime disabled, between the :c:func:`device_link_add()` and
+:c:func:`device_link_del()` or :c:func:`device_link_remove()` calls.]
 
 Sometimes drivers depend on optional resources.  They are able to operate
 in a degraded mode (reduced feature set or performance) when those resources
@@ -285,4 +321,4 @@ API
 ===
 
 .. kernel-doc:: drivers/base/core.c
-   :functions: device_link_add device_link_del
+   :functions: device_link_add device_link_del device_link_remove
diff --git a/Makefile b/Makefile
index d5713e7b1e50..f070e0d65186 100644
--- a/Makefile
+++ b/Makefile
@@ -583,7 +583,7 @@ export KBUILD_MODULES KBUILD_BUILTIN
 ifeq ($(KBUILD_EXTMOD),)
 # Objects we will link into vmlinux / subdirs we need to visit
 init-y		:= init/
-drivers-y	:= drivers/ sound/ firmware/
+drivers-y	:= drivers/ sound/
 net-y		:= net/
 libs-y		:= lib/
 core-y		:= usr/
diff --git a/arch/powerpc/platforms/pseries/ibmebus.c b/arch/powerpc/platforms/pseries/ibmebus.c
index 5b4a56131904..84e8ec4011ba 100644
--- a/arch/powerpc/platforms/pseries/ibmebus.c
+++ b/arch/powerpc/platforms/pseries/ibmebus.c
@@ -261,8 +261,7 @@ static char *ibmebus_chomp(const char *in, size_t count)
 	return out;
 }
 
-static ssize_t ibmebus_store_probe(struct bus_type *bus,
-				   const char *buf, size_t count)
+static ssize_t probe_store(struct bus_type *bus, const char *buf, size_t count)
 {
 	struct device_node *dn = NULL;
 	struct device *dev;
@@ -298,10 +297,9 @@ out:
 		return rc;
 	return count;
 }
-static BUS_ATTR(probe, 0200, NULL, ibmebus_store_probe);
+static BUS_ATTR_WO(probe);
 
-static ssize_t ibmebus_store_remove(struct bus_type *bus,
-				    const char *buf, size_t count)
+static ssize_t remove_store(struct bus_type *bus, const char *buf, size_t count)
 {
 	struct device *dev;
 	char *path;
@@ -325,7 +323,7 @@ static ssize_t ibmebus_store_remove(struct bus_type *bus,
 		return -ENODEV;
 	}
 }
-static BUS_ATTR(remove, 0200, NULL, ibmebus_store_remove);
+static BUS_ATTR_WO(remove);
 
 static struct attribute *ibmbus_bus_attrs[] = {
 	&bus_attr_probe.attr,
diff --git a/drivers/base/base.h b/drivers/base/base.h
index 7a419a7a6235..b405436ee28e 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -60,12 +60,17 @@ struct driver_private {
  * @knode_parent - node in sibling list
  * @knode_driver - node in driver list
  * @knode_bus - node in bus list
+ * @knode_class - node in class list
  * @deferred_probe - entry in deferred_probe_list which is used to retry the
  *	binding of drivers which were unable to get all the resources needed by
  *	the device; typically because it depends on another driver getting
  *	probed first.
+ * @async_driver - pointer to device driver awaiting probe via async_probe
  * @device - pointer back to the struct device that this structure is
  * associated with.
+ * @dead - This device is currently either in the process of or has been
+ *	removed from the system. Any asynchronous events scheduled for this
+ *	device should exit without taking any action.
  *
  * Nothing outside of the driver core should ever touch these fields.
  */
@@ -74,8 +79,11 @@ struct device_private {
 	struct klist_node knode_parent;
 	struct klist_node knode_driver;
 	struct klist_node knode_bus;
+	struct klist_node knode_class;
 	struct list_head deferred_probe;
+	struct device_driver *async_driver;
 	struct device *device;
+	u8 dead:1;
 };
 #define to_device_private_parent(obj)	\
 	container_of(obj, struct device_private, knode_parent)
@@ -83,6 +91,8 @@ struct device_private {
 	container_of(obj, struct device_private, knode_driver)
 #define to_device_private_bus(obj)	\
 	container_of(obj, struct device_private, knode_bus)
+#define to_device_private_class(obj)	\
+	container_of(obj, struct device_private, knode_class)
 
 /* initialisation functions */
 extern int devices_init(void);
@@ -124,6 +134,8 @@ extern int driver_add_groups(struct device_driver *drv,
 			     const struct attribute_group **groups);
 extern void driver_remove_groups(struct device_driver *drv,
 				 const struct attribute_group **groups);
+int device_driver_attach(struct device_driver *drv, struct device *dev);
+void device_driver_detach(struct device *dev);
 
 extern char *make_class_name(const char *name, struct kobject *kobj);
 
diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index e06a57936cc9..0a58e969f8b7 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -187,11 +187,7 @@ static ssize_t unbind_store(struct device_driver *drv, const char *buf,
 
 	dev = bus_find_device_by_name(bus, NULL, buf);
 	if (dev && dev->driver == drv) {
-		if (dev->parent && dev->bus->need_parent_lock)
-			device_lock(dev->parent);
-		device_release_driver(dev);
-		if (dev->parent && dev->bus->need_parent_lock)
-			device_unlock(dev->parent);
+		device_driver_detach(dev);
 		err = count;
 	}
 	put_device(dev);
@@ -214,13 +210,7 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
 
 	dev = bus_find_device_by_name(bus, NULL, buf);
 	if (dev && dev->driver == NULL && driver_match_device(drv, dev)) {
-		if (dev->parent && bus->need_parent_lock)
-			device_lock(dev->parent);
-		device_lock(dev);
-		err = driver_probe_device(drv, dev);
-		device_unlock(dev);
-		if (dev->parent && bus->need_parent_lock)
-			device_unlock(dev->parent);
+		err = device_driver_attach(drv, dev);
 
 		if (err > 0) {
 			/* success */
@@ -236,12 +226,12 @@ static ssize_t bind_store(struct device_driver *drv, const char *buf,
 }
 static DRIVER_ATTR_IGNORE_LOCKDEP(bind, S_IWUSR, NULL, bind_store);
 
-static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf)
+static ssize_t drivers_autoprobe_show(struct bus_type *bus, char *buf)
 {
 	return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);
 }
 
-static ssize_t store_drivers_autoprobe(struct bus_type *bus,
+static ssize_t drivers_autoprobe_store(struct bus_type *bus,
 				       const char *buf, size_t count)
 {
 	if (buf[0] == '0')
@@ -251,7 +241,7 @@ static ssize_t store_drivers_autoprobe(struct bus_type *bus,
 	return count;
 }
 
-static ssize_t store_drivers_probe(struct bus_type *bus,
+static ssize_t drivers_probe_store(struct bus_type *bus,
 				   const char *buf, size_t count)
 {
 	struct device *dev;
@@ -586,9 +576,8 @@ static void remove_bind_files(struct device_driver *drv)
 	driver_remove_file(drv, &driver_attr_unbind);
 }
 
-static BUS_ATTR(drivers_probe, S_IWUSR, NULL, store_drivers_probe);
-static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,
-		show_drivers_autoprobe, store_drivers_autoprobe);
+static BUS_ATTR_WO(drivers_probe);
+static BUS_ATTR_RW(drivers_autoprobe);
 
 static int add_probe_files(struct bus_type *bus)
 {
@@ -621,17 +610,6 @@ static ssize_t uevent_store(struct device_driver *drv, const char *buf,
 }
 static DRIVER_ATTR_WO(uevent);
 
-static void driver_attach_async(void *_drv, async_cookie_t cookie)
-{
-	struct device_driver *drv = _drv;
-	int ret;
-
-	ret = driver_attach(drv);
-
-	pr_debug("bus: '%s': driver %s async attach completed: %d\n",
-		 drv->bus->name, drv->name, ret);
-}
-
 /**
  * bus_add_driver - Add a driver to the bus.
  * @drv: driver.
@@ -664,15 +642,9 @@ int bus_add_driver(struct device_driver *drv)
 
 	klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
 	if (drv->bus->p->drivers_autoprobe) {
-		if (driver_allows_async_probing(drv)) {
-			pr_debug("bus: '%s': probing driver %s asynchronously\n",
-				drv->bus->name, drv->name);
-			async_schedule(driver_attach_async, drv);
-		} else {
-			error = driver_attach(drv);
-			if (error)
-				goto out_unregister;
-		}
+		error = driver_attach(drv);
+		if (error)
+			goto out_unregister;
 	}
 	module_add_driver(drv->owner, drv);
 
@@ -774,13 +746,8 @@ EXPORT_SYMBOL_GPL(bus_rescan_devices);
  */
 int device_reprobe(struct device *dev)
 {
-	if (dev->driver) {
-		if (dev->parent && dev->bus->need_parent_lock)
-			device_lock(dev->parent);
-		device_release_driver(dev);
-		if (dev->parent && dev->bus->need_parent_lock)
-			device_unlock(dev->parent);
-	}
+	if (dev->driver)
+		device_driver_detach(dev);
 	return bus_rescan_devices_helper(dev, NULL);
 }
 EXPORT_SYMBOL_GPL(device_reprobe);
@@ -838,7 +805,14 @@ static ssize_t bus_uevent_store(struct bus_type *bus,
 	rc = kobject_synth_uevent(&bus->p->subsys.kobj, buf, count);
 	return rc ? rc : count;
 }
-static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);
+/*
+ * "open code" the old BUS_ATTR() macro here.  We want to use BUS_ATTR_WO()
+ * here, but can not use it as earlier in the file we have
+ * DEVICE_ATTR_WO(uevent), which would cause a clash with the with the store
+ * function name.
+ */
+static struct bus_attribute bus_attr_uevent = __ATTR(uevent, S_IWUSR, NULL,
+						     bus_uevent_store);
 
 /**
  * bus_register - register a driver-core subsystem
diff --git a/drivers/base/class.c b/drivers/base/class.c
index 54def4e02f00..d8a6a5864c2e 100644
--- a/drivers/base/class.c
+++ b/drivers/base/class.c
@@ -117,16 +117,22 @@ static void class_put(struct class *cls)
 		kset_put(&cls->p->subsys);
 }
 
+static struct device *klist_class_to_dev(struct klist_node *n)
+{
+	struct device_private *p = to_device_private_class(n);
+	return p->device;
+}
+
 static void klist_class_dev_get(struct klist_node *n)
 {
-	struct device *dev = container_of(n, struct device, knode_class);
+	struct device *dev = klist_class_to_dev(n);
 
 	get_device(dev);
 }
 
 static void klist_class_dev_put(struct klist_node *n)
 {
-	struct device *dev = container_of(n, struct device, knode_class);
+	struct device *dev = klist_class_to_dev(n);
 
 	put_device(dev);
 }
@@ -277,7 +283,7 @@ void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
 	struct klist_node *start_knode = NULL;
 
 	if (start)
-		start_knode = &start->knode_class;
+		start_knode = &start->p->knode_class;
 	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
 	iter->type = type;
 }
@@ -304,7 +310,7 @@ struct device *class_dev_iter_next(struct class_dev_iter *iter)
 		knode = klist_next(&iter->ki);
 		if (!knode)
 			return NULL;
-		dev = container_of(knode, struct device, knode_class);
+		dev = klist_class_to_dev(knode);
 		if (!iter->type || iter->type == dev->type)
 			return dev;
 	}
diff --git a/drivers/base/component.c b/drivers/base/component.c
index 7dbc41cccd58..532a3a5d8f63 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -27,7 +27,7 @@
  * helper fills the niche of aggregate drivers for specific hardware, where
  * further standardization into a subsystem would not be practical. The common
  * example is when a logical device (e.g. a DRM display driver) is spread around
- * the SoC on various component (scanout engines, blending blocks, transcoders
+ * the SoC on various components (scanout engines, blending blocks, transcoders
  * for various outputs and so on).
  *
  * The component helper also doesn't solve runtime dependencies, e.g. for system
@@ -378,7 +378,7 @@ static void __component_match_add(struct device *master,
 }
 
 /**
- * component_match_add_release - add a component match with release callback
+ * component_match_add_release - add a component match entry with release callback
  * @master: device with the aggregate driver
  * @matchptr: pointer to the list of component matches
  * @release: release function for @compare_data
@@ -408,7 +408,7 @@ void component_match_add_release(struct device *master,
 EXPORT_SYMBOL(component_match_add_release);
 
 /**
- * component_match_add_typed - add a compent match for a typed component
+ * component_match_add_typed - add a component match entry for a typed component
  * @master: device with the aggregate driver
  * @matchptr: pointer to the list of component matches
  * @compare_typed: compare function to match against all typed components
@@ -537,11 +537,11 @@ static void component_unbind(struct component *component,
 }
 
 /**
- * component_unbind_all - unbind all component to an aggregate driver
+ * component_unbind_all - unbind all components of an aggregate driver
  * @master_dev: device with the aggregate driver
  * @data: opaque pointer, passed to all components
  *
- * Unbinds all components to the aggregate @dev by passing @data to their
+ * Unbinds all components of the aggregate @dev by passing @data to their
  * &component_ops.unbind functions. Should be called from
  * &component_master_ops.unbind.
  */
@@ -619,11 +619,11 @@ static int component_bind(struct component *component, struct master *master,
 }
 
 /**
- * component_bind_all - bind all component to an aggregate driver
+ * component_bind_all - bind all components of an aggregate driver
  * @master_dev: device with the aggregate driver
  * @data: opaque pointer, passed to all components
  *
- * Binds all components to the aggregate @dev by passing @data to their
+ * Binds all components of the aggregate @dev by passing @data to their
  * &component_ops.bind functions. Should be called from
  * &component_master_ops.bind.
  */
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 0073b09bb99f..4aeaa0c92bda 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -179,10 +179,31 @@ void device_pm_move_to_tail(struct device *dev)
  * of the link.  If DL_FLAG_PM_RUNTIME is not set, DL_FLAG_RPM_ACTIVE will be
  * ignored.
  *
- * If the DL_FLAG_AUTOREMOVE_CONSUMER is set, the link will be removed
- * automatically when the consumer device driver unbinds from it.
- * The combination of both DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_STATELESS
- * set is invalid and will cause NULL to be returned.
+ * If DL_FLAG_STATELESS is set in @flags, the link is not going to be managed by
+ * the driver core and, in particular, the caller of this function is expected
+ * to drop the reference to the link acquired by it directly.
+ *
+ * If that flag is not set, however, the caller of this function is handing the
+ * management of the link over to the driver core entirely and its return value
+ * can only be used to check whether or not the link is present.  In that case,
+ * the DL_FLAG_AUTOREMOVE_CONSUMER and DL_FLAG_AUTOREMOVE_SUPPLIER device link
+ * f