Merge branch 'leds-trigger-netdev-add-additional-modes'

Merge branch 'leds-trigger-netdev-add-additional-modes'

Christian Marangi says:

====================
leds: trigger: netdev: add additional modes

This is a continue of [1]. It was decided to take a more gradual
approach to implement LEDs support for switch and phy starting with
basic support and then implementing the hw control part when we have all
the prereq done.

This should be the final part for the netdev trigger.
I added net-next tag and added netdev mailing list since I was informed
that this should be merged with netdev branch.

We collect some info around and we found a good set of modes that are
common in almost all the PHY and Switch.

These modes are:
- Modes for dedicated link speed(10, 100, 1000 mbps). Additional mode
  can be added later following this example.
- Modes for half and full duplex.

The original idea was to add hw control only modes.
While the concept makes sense in practice it would results in lots of
additional code and extra check to make sure we are setting correct modes.

With the suggestion from Andrew it was pointed out that using the ethtool
APIs we can actually get the current link speed and duplex and this
effectively removed the problem of having hw control only modes since we
can fallback to software.

Since these modes are supported by software, we can skip providing an
user for this in the LED driver to support hw control for these new modes
(that will come right after this is merged) and prevent this to be another
multi subsystem series.

For link speed and duplex we use ethtool APIs.

To call ethtool APIs, rtnl lock is needed but this can be skipped on
handling netdev events as the lock is already held.

[1] https://lore.kernel.org/lkml/20230216013230.22978-1-ansuelsmth@gmail.com/
====================

Link: https://lore.kernel.org/r/20230619204700.6665-1-ansuelsmth@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>