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
  ...

1 files changed, 60 insertions, 24 deletions

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