Commit 9a3d7fd2 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'driver-core-5.5-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" set of driver core patches for 5.5-rc1

  There's a few minor cleanups and fixes in here, but the majority of
  the patches in here fall into two buckets:

   - debugfs api cleanups and fixes

   - driver core device link support for boot dependancy issues

  The debugfs api cleanups are working to slowly refactor the debugfs
  apis so that it is even harder to use incorrectly. That work has been
  happening for the past few kernel releases and will continue over
  time, it's a long-term project/goal

  The driver core device link support missed 5.4 by just a bit, so it's
  been sitting and baking for many months now. It's from Saravana Kannan
  to help resolve the problems that DT-based systems have at boot time
  with dependancy graphs and kernel modules. Turns out that no one has
  actually tried to build a generic arm64 kernel with loads of modules
  and have it "just work" for a variety of platforms (like a distro
  kernel). The big problem turned out to be a lack of dependency
  information between different areas of DT entries, and the work here
  resolves that problem and now allows devices to boot properly, and
  quicker than a monolith kernel.

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

* tag 'driver-core-5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (68 commits)
  tracing: Remove unnecessary DEBUG_FS dependency
  of: property: Add device link support for interrupt-parent, dmas and -gpio(s)
  debugfs: Fix !DEBUG_FS debugfs_create_automount
  of: property: Add device link support for "iommu-map"
  of: property: Fix the semantics of of_is_ancestor_of()
  i2c: of: Populate fwnode in of_i2c_get_board_info()
  drivers: base: Fix Kconfig indentation
  firmware_loader: Fix labels with comma for builtin firmware
  driver core: Allow device link operations inside sync_state()
  driver core: platform: Declare ret variable only once
  cpu-topology: declare parse_acpi_topology in <linux/arch_topology.h>
  crypto: hisilicon: no need to check return value of debugfs_create functions
  driver core: platform: use the correct callback type for bus_find_device
  firmware_class: make firmware caching configurable
  driver core: Clarify documentation for fwnode_operations.add_links()
  mailbox: tegra: Fix superfluous IRQ error message
  net: caif: Fix debugfs on 64-bit platforms
  mac80211: Use debugfs_create_xul() helper
  media: c8sectpfe: no need to check return value of debugfs_create functions
  of: property: Add device link support for iommus, mboxes and io-channels
  ...
parents 0dd09bc0 0e4a459f

Documentation/admin-guide/kernel-parameters.rst

+1 −0
Original line number Diff line number Diff line
@@ -127,6 +127,7 @@ parameter is applicable:: 
	NET	Appropriate network support is enabled.

	NUMA	NUMA support is enabled.

	NFS	Appropriate NFS support is enabled.

	OF	Devicetree is enabled.

	OSS	OSS sound support is enabled.

	PV_OPS	A paravirtualized kernel is enabled.

	PARIDE	The ParIDE (parallel port IDE) subsystem is enabled.

Documentation/admin-guide/kernel-parameters.txt

+6 −0
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@@ -3240,6 +3240,12 @@ 
			This can be set from sysctl after boot.

			See Documentation/admin-guide/sysctl/vm.rst for details.



	of_devlink	[OF, KNL] Create device links between consumer and

			supplier devices by scanning the devictree to infer the

			consumer/supplier relationships.  A consumer device

			will not be probed until all the supplier devices have

			probed successfully.



	ohci1394_dma=early	[HW] enable debugging via the ohci1394 driver.

			See Documentation/debugging-via-ohci1394.txt for more

			info.

Documentation/driver-api/device_link.rst

+2 −1
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@@ -281,7 +281,8 @@ State machine 
  :c:func:`driver_bound()`.)



* Before a consumer device is probed, presence of supplier drivers is

  verified by checking that links to suppliers are in ``DL_STATE_AVAILABLE``

  verified by checking the consumer device is not in the wait_for_suppliers

  list and by checking that links to suppliers are in ``DL_STATE_AVAILABLE``

  state.  The state of the links is updated to ``DL_STATE_CONSUMER_PROBE``.

  (Call to :c:func:`device_links_check_suppliers()` from

  :c:func:`really_probe()`.)

Documentation/driver-api/driver-model/devres.rst

+4 −0
Original line number Diff line number Diff line
@@ -316,6 +316,10 @@ IOMAP 
  devm_ioremap_nocache()

  devm_ioremap_wc()

  devm_ioremap_resource() : checks resource, requests memory region, ioremaps

  devm_ioremap_resource_wc()

  devm_platform_ioremap_resource() : calls devm_ioremap_resource() for platform device

  devm_platform_ioremap_resource_wc()

  devm_platform_ioremap_resource_byname()

  devm_iounmap()

  pcim_iomap()

  pcim_iomap_regions()	: do request_region() and iomap() on multiple BARs

Documentation/driver-api/driver-model/driver.rst

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@@ -169,6 +169,49 @@ A driver's probe() may return a negative errno value to indicate that 
the driver did not bind to this device, in which case it should have

released all resources it allocated::



	void (*sync_state)(struct device *dev);



sync_state is called only once for a device. It's called when all the consumer

devices of the device have successfully probed. The list of consumers of the

device is obtained by looking at the device links connecting that device to its

consumer devices.



The first attempt to call sync_state() is made during late_initcall_sync() to

give firmware and drivers time to link devices to each other. During the first

attempt at calling sync_state(), if all the consumers of the device at that

point in time have already probed successfully, sync_state() is called right

away. If there are no consumers of the device during the first attempt, that

too is considered as "all consumers of the device have probed" and sync_state()

is called right away.



If during the first attempt at calling sync_state() for a device, there are

still consumers that haven't probed successfully, the sync_state() call is

postponed and reattempted in the future only when one or more consumers of the

device probe successfully. If during the reattempt, the driver core finds that

there are one or more consumers of the device that haven't probed yet, then

sync_state() call is postponed again.



A typical use case for sync_state() is to have the kernel cleanly take over

management of devices from the bootloader. For example, if a device is left on

and at a particular hardware configuration by the bootloader, the device's

driver might need to keep the device in the boot configuration until all the

consumers of the device have probed. Once all the consumers of the device have

probed, the device's driver can synchronize the hardware state of the device to

match the aggregated software state requested by all the consumers. Hence the

name sync_state().



While obvious examples of resources that can benefit from sync_state() include

resources such as regulator, sync_state() can also be useful for complex

resources like IOMMUs. For example, IOMMUs with multiple consumers (devices

whose addresses are remapped by the IOMMU) might need to keep their mappings

fixed at (or additive to) the boot configuration until all its consumers have

probed.



While the typical use case for sync_state() is to have the kernel cleanly take

over management of devices from the bootloader, the usage of sync_state() is

not restricted to that. Use it whenever it makes sense to take an action after

all the consumers of a device have probed.



	int 	(*remove)	(struct device *dev);



remove is called to unbind a driver from a device. This may be

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