Merge branch 'add-alcd-support-to-cable-testing-interface'

Oleksij Rempel says:

====================
Add ALCD Support to Cable Testing Interface

This patch series introduces support for Active Link Cable Diagnostics
(ALCD) in the ethtool cable testing interface and the DP83TD510 PHY
driver.

Why ALCD?
On a 10BaseT1L interface, TDR (Time Domain Reflectometry) is not
possible if the link partner is active - TDR will fail in these cases
because it requires interrupting the link. Since the link is active, we
already know the cable is functioning, so instead of using TDR, we can
use ALCD.

ALCD lets us measure cable length without disrupting the active link,
which is crucial in environments where network uptime is important. It
provides a way to gather diagnostic data without the need for downtime.

What's in this series:
- Extended the ethtool cable testing interface to specify the source of
  diagnostic results (TDR or ALCD).
- Updated the DP83TD510 PHY driver to use ALCD when the link is
  active, ensuring we can still get cable length info without dropping the
  connection.
====================

Link: https://patch.msgid.link/20240822120703.1393130-1-o.rempel@pengutronix.de


Signed-off-by: Jakub Kicinski <kuba@kernel.org>