evlink: Add boot-time eswitch mode defaults

This series adds a devlink_eswitch_mode= kernel command line parameter
for setting a default devlink eswitch mode during boot.

Following the discussion with Jakub[1] and the feedback on the RFC
postings, this version keeps the scope limited to a boot-time devlink
eswitch mode default only.

The option selects either all devlink handles or an explicit
comma-separated handle list:

devlink_eswitch_mode=*=switchdev
devlink_eswitch_mode=pci/0000:08:00.0,pci/0000:09:00.1=switchdev_inactive

The supported modes are legacy, switchdev and switchdev_inactive. The
selected mode is applied through the existing eswitch_mode_set() devlink
operation, the same operation used by the devlink eswitch mode command.

Registration may happen before a driver is ready to change eswitch mode,
so devlink core queues an asynchronous apply request from devl_register().
The worker takes the devlink instance lock before calling into the driver.

After a successful reload that performed DRIVER_REINIT, devlink core
already holds the devlink instance lock and the driver completed
reload_up(), so the default is applied directly from the reload path.

Drivers that know exactly when the device is ready can call
devl_apply_default_esw_mode() directly. mlx5 uses this after initial
probe, when the device is initialized and the devlink lock is already
held.

Patch 1 clears the mlx5 FW reset-in-progress bit before reload.

Patch 2 factors the common eswitch mode set validation into a helper.

Patch 3 adds the devlink_eswitch_mode= parser and documentation.

Patch 4 applies parsed defaults from devlink core.

Patch 5 adds devl_apply_default_esw_mode() for drivers.

Patch 6 wires mlx5 to apply the default after initial probe.

Changelog:

v3 -> v4:

- Rework registration time apply to use per devlink delayed work instead
  of calling eswitch_mode_set() directly from devl_register().

- Apply the default directly after successful DRIVER_REINIT devlink reload,
  where the devlink lock is already held and reload_up() has completed.

- Add devl_apply_default_esw_mode() for drivers that know their exact ready
  point.

- Drop the driver registration-ordering preparation patches that are no
  longer needed with the async registration apply path.

v2 -> v3:

- Change the devlink_eswitch_mode= API syntax to use <selector>=<mode>
  instead of [<selector>]:<mode>, following a comment from Randy Dunlap.

v1 -> v2:

- Move default eswitch mode application into devlink core. The default is
  now applied during devlink registration and after a successful devlink
  reload that performed DRIVER_REINIT.

- Remove the exported devl_apply_default_esw_mode() driver API and the mlx5
  driver-side call to it.

- Skip devlink health recovery notifications while the devlink instance is
  not registered, so drivers can move registration later without early
  health work hitting registration assertions.

- Move mlx5 devlink registration after device initialization, including the
  lightweight init path, so the core can apply the default through the
  normal registration flow.

- Move the matching netdevsim and mlx5 unregister paths before object
  teardown, so unregister notifications come from devl_unregister() and the
  later object teardown paths run while the devlink instance is no longer
  registered.

- Add registration-ordering preparation patches for netdevsim and octeontx2
  AF/PF, so their eswitch state is ready before registration-time defaults
  may call eswitch_mode_set().

[1] lore.kernel.org/r/20260502184153.4fd8d06f@kernel.org/
RFC v1: lore.kernel.org/r/20260506123739.1959770-1-mbloch@nvidia.com/
RFC v2: lore.kernel.org/r/20260510185424.2041415-1-mbloch@nvidia.com/
v1: lore.kernel.org/r/20260521072434.362624-1-tariqt@nvidia.com/
v2: lore.kernel.org/all/20260603193259.3412464-1-mbloch@nvidia.com/
v3: lore.kernel.org/all/20260605181030.3486619-1-mbloch@nvidia.com/

Mark Bloch (6):
  net/mlx5: Clear FW reset-in-progress bit before reload
  devlink: Factor out eswitch mode setting
  devlink: Parse eswitch mode boot defaults
  devlink: Apply eswitch mode boot defaults
  devlink: Add API to apply eswitch mode boot default
  net/mlx5: Apply devlink eswitch mode boot default on probe

 .../admin-guide/kernel-parameters.txt         |  25 ++
 .../networking/devlink/devlink-defaults.rst   |  78 ++++
 Documentation/networking/devlink/index.rst    |   1 +
 .../ethernet/mellanox/mlx5/core/fw_reset.c    |  28 +-
 .../net/ethernet/mellanox/mlx5/core/main.c    |  13 +
 include/net/devlink.h                         |   1 +
 net/devlink/core.c                            | 393 ++++++++++++++++++
 net/devlink/dev.c                             |  33 +-
 net/devlink/devl_internal.h                   |   8 +
 9 files changed, 562 insertions(+), 18 deletions(-)
 create mode 100644 Documentation/networking/devlink/devlink-defaults.rst


base-commit: 805185b7c7a1069e407b6f7b3bc98e44d415f484
-- 
2.43.0