mlxbf-gige: autonegotiation fails to complete on BF2

[Asmaa Mnebhi]

SRU Justification:

[Impact]

During the reboot test, QA found an intermittent issue where the OOB link is down.
The link is down because the KSZ9031 PHY fails to complete autonegotiation.
Even under "normal" circumstances where autonegotiation completes,
it takes an abnormal time to do so (on average, at least 8 seconds).

Hence, the hardware team and Microchip are involved in this debug but the root cause is still unknown.
In the meantime, we need to provide a software workaround since customers are starting to see this issue as well.

[Fix]

* Restart autonegotiation when it fails the first time.

[Test Case]

* On BF2, Do the reboot test: 2000 loops.
* Check that the OOB link is up and ip is assigned.

[Regression Potential]

* no known regression.

[Other]
* Note that this issue is BF2 hardware specific. The same ethernet code is used for BF3 and we don't see any issues. In fact, the link up time on BF3 <= 1s. On BF2, the link up time is > 8s.
* we have been aware of this issue for 2 years and have shared this with the PHY vendor and the hardware team but there were not root causes identified.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.4.0-1086.93 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-focal-linux-bluefield' to 'verification-done-focal-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-focal-linux-bluefield' to 'verification-failed-focal-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is awaiting verification that the linux-bluefield/5.15.0-1044.46 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-done-jammy-linux-bluefield'. If the problem still exists, change the tag 'verification-needed-jammy-linux-bluefield' to 'verification-failed-jammy-linux-bluefield'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Feysel Mohammed (feyselm)]

Using 5.15.0-1044-bluefield, After 2000 reboots, OOB link is up and ip is assigned.

[Feysel Mohammed (feyselm)]

Using 5.4.0-1086-bluefield, After 2000 reboots, OOB link is up and ip is assigned.