This sync_state driver/bus callback is called once all the consumers
of a supplier have probed successfully.
This allows the supplier device's driver/bus to sync the supplier
device's state to the software state with the guarantee that all the
consumers are actively managing the resources provided by the supplier
device.
To maintain backwards compatibility and ease transition from existing
frameworks and resource cleanup schemes, late_initcall_sync is the
earliest when the sync_state callback might be called.
There is no upper bound on the time by which the sync_state callback
has to be called. This is because if a consumer device never probes,
the supplier has to maintain its resources in the state left by the
bootloader. For example, if the bootloader leaves the display
backlight at a fixed voltage and the backlight driver is never probed,
you don't want the backlight to ever be turned off after boot up.
Also, when multiple devices are added after kernel init, some
suppliers could be added before their consumer devices get added. In
these instances, the supplier devices could get their sync_state
callback called right after they probe because the consumers devices
haven't had a chance to create device links to the suppliers.
To handle this correctly, this change also provides APIs to
pause/resume sync state callbacks so that when multiple devices are
added, their sync_state callback evaluation can be postponed to happen
after all of them are added.
kbuild test robot reported missing documentation for device.state_synced
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20190904211126.47518-5-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The firmware corresponding to a device (dev.fwnode) might be able to
provide functional dependency information between a device and its
supplier and consumer devices. Tracking this functional dependency
allows optimizing device probe order and informing a supplier when all
its consumers have probed (and thereby actively managing their
resources).
The existing device links feature allows tracking and using
supplier-consumer relationships. So, this patch adds the add_links()
fwnode callback to allow firmware to create device links for each
device as the device is added.
However, when consumer devices are added, they might not have a supplier
device to link to despite needing mandatory resources/functionality from
one or more suppliers. A waiting_for_suppliers list is created to track
such consumers and retry linking them when new devices get added.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20190904211126.47518-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Pull USB updates from Greg KH:
"Here is the big set of USB patches for 5.4-rc1.
Two major chunks of code are moving out of the tree and into the
staging directory, uwb and wusb (wireless USB support), because there
are no devices that actually use this protocol anymore, and what we
have today probably doesn't work at all given that the maintainers
left many many years ago. So move it to staging where it will be
removed in a few releases if no one screams.
Other than that, lots of little things. The usual gadget and xhci and
usb serial driver updates, along with a bunch of sysfs file cleanups
due to the driver core changes to support that. Nothing really major,
just constant forward progress.
All of these have been in linux-next for a while with no reported
issues"
* tag 'usb-5.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (159 commits)
USB: usbcore: Fix slab-out-of-bounds bug during device reset
usb: cdns3: Remove redundant dev_err call in cdns3_probe()
USB: rio500: Fix lockdep violation
USB: rio500: simplify locking
usb: mtu3: register a USB Role Switch for dual role mode
usb: common: add USB GPIO based connection detection driver
usb: common: create Kconfig file
usb: roles: get usb-role-switch from parent
usb: roles: Add fwnode_usb_role_switch_get() function
device connection: Add fwnode_connection_find_match()
usb: roles: Introduce stubs for the exiting functions in role.h
dt-bindings: usb: mtu3: add properties about USB Role Switch
dt-bindings: usb: add binding for USB GPIO based connection detection driver
dt-bindings: connector: add optional properties for Type-B
dt-binding: usb: add usb-role-switch property
usbip: Implement SG support to vhci-hcd and stub driver
usb: roles: intel: Enable static DRD mode for role switch
xhci-ext-caps.c: Add property to disable Intel SW switch
usb: dwc3: remove generic PHY calibrate() calls
usb: core: phy: add support for PHY calibration
...
This reverts commit 5302dd7dd0.
Based on a lot of email and in-person discussions, this patch series is
being reworked to address a number of issues that were pointed out that
needed to be taken care of before it should be merged. It will be
resubmitted with those changes hopefully soon.
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 134b23eec9.
Based on a lot of email and in-person discussions, this patch series is
being reworked to address a number of issues that were pointed out that
needed to be taken care of before it should be merged. It will be
resubmitted with those changes hopefully soon.
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 8f8184d6bf.
Based on a lot of email and in-person discussions, this patch series is
being reworked to address a number of issues that were pointed out that
needed to be taken care of before it should be merged. It will be
resubmitted with those changes hopefully soon.
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Saravana Kannan <saravanak@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dev_groups added to struct driver
Persistent tag for others to pull this branch from
This is the first patch in a longer series that adds the ability for the
driver core to create and remove a list of attribute groups
automatically when the device is bound/unbound from a specific driver.
See:
https://lore.kernel.org/r/20190731124349.4474-2-gregkh@linuxfoundation.org
for details on this patch, and examples of how to use it in other
drivers.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dev_groups added to struct driver
Persistent tag for others to pull this branch from
This is the first patch in a longer series that adds the ability for the
driver core to create and remove a list of attribute groups
automatically when the device is bound/unbound from a specific driver.
See:
https://lore.kernel.org/r/20190731124349.4474-2-gregkh@linuxfoundation.org
for details on this patch, and examples of how to use it in other
drivers.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This sync_state driver/bus callback is called once all the consumers
of a supplier have probed successfully.
This allows the supplier device's driver/bus to sync the supplier
device's state to the software state with the guarantee that all the
consumers are actively managing the resources provided by the supplier
device.
To maintain backwards compatibility and ease transition from existing
frameworks and resource cleanup schemes, late_initcall_sync is the
earliest when the sync_state callback might be called.
There is no upper bound on the time by which the sync_state callback
has to be called. This is because if a consumer device never probes,
the supplier has to maintain its resources in the state left by the
bootloader. For example, if the bootloader leaves the display
backlight at a fixed voltage and the backlight driver is never probed,
you don't want the backlight to ever be turned off after boot up.
Also, when multiple devices are added after kernel init, some
suppliers could be added before their consumer devices get added. In
these instances, the supplier devices could get their sync_state
callback called right after they probe because the consumers devices
haven't had a chance to create device links to the suppliers.
To handle this correctly, this change also provides APIs to
pause/resume sync state callbacks so that when multiple devices are
added, their sync_state callback evaluation can be postponed to happen
after all of them are added.
kbuild test robot reported missing documentation for device.state_synced
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20190731221721.187713-5-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The driver core/bus adding supplier-consumer dependencies by default
enables functional dependencies to be tracked correctly even when the
consumer devices haven't had their drivers registered or loaded (if they
are modules).
However, when the bus incorrectly adds dependencies that it shouldn't
have added, the devices might never probe.
For example, if device-C is a consumer of device-S and they have
phandles to each other in DT, the following could happen:
1. Device-S get added first.
2. The bus add_links() callback will (incorrectly) try to link it as
a consumer of device-C.
3. Since device-C isn't present, device-S will be put in
"waiting-for-supplier" list.
4. Device-C gets added next.
5. All devices in "waiting-for-supplier" list are retried for linking.
6. Device-S gets linked as consumer to Device-C.
7. The bus add_links() callback will (correctly) try to link it as
a consumer of device-S.
8. This isn't allowed because it would create a cyclic device links.
Neither devices will get probed since the supplier is marked as
dependent on the consumer. And the consumer will never probe because the
consumer can't get resources from the supplier.
Without this patch, things stay in this broken state. However, with this
patch, the execution will continue like this:
9. Device-C's driver is loaded.
10. Device-C's driver removes Device-S as a consumer of Device-C.
11. Device-C's driver adds Device-C as a consumer of Device-S.
12. Device-S probes.
14. Device-C probes.
kbuild test robot reported missing documentation for device.has_edit_links
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20190731221721.187713-3-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When devices are added, the bus might want to create device links to track
functional dependencies between supplier and consumer devices. This
tracking of supplier-consumer relationship allows optimizing device probe
order and tracking whether all consumers of a supplier are active. The
add_links bus callback is added to support this.
However, when consumer devices are added, they might not have a supplier
device to link to despite needing mandatory resources/functionality from
one or more suppliers. A waiting_for_suppliers list is created to track
such consumers and retry linking them when new devices get added.
Signed-off-by: Saravana Kannan <saravanak@google.com>
Link: https://lore.kernel.org/r/20190731221721.187713-2-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Document the parameters for bus_find_next_device() to avoid
htmldocs build warnings as reported below :
include/linux/device.h:236: warning: Function parameter or member 'bus' not described in 'bus_find_next_device'
include/linux/device.h:236: warning: Function parameter or member 'cur' not described in 'bus_find_next_device'
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20190801102026.27312-3-suzuki.poulose@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Saravana Kannan
Linus Torvalds
Greg Kroah-Hartman
Heikki Krogerus
Suzuki K Poulose
Dmitry Torokhov