[Bug 1930645] Re: Fix Ethernet not working by hotplug - RTL8106E

** No longer affects: linux-oem (Ubuntu)

** No longer affects: linux-oem (Ubuntu Focal)

** No longer affects: linux-oem (Ubuntu Hirsute)

** No longer affects: linux-oem (Ubuntu Impish)

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https://bugs.launchpad.net/bugs/1930645

Title:
Fix Ethernet not working by hotplug - RTL8106E

Status in HWE Next:
New
Status in linux package in Ubuntu:
In Progress
Status in linux-oem-5.10 package in Ubuntu:
Invalid
Status in linux-oem-5.13 package in Ubuntu:
Invalid
Status in linux source package in Focal:
Won't Fix
Status in linux-oem-5.10 source package in Focal:
Fix Released
Status in linux-oem-5.13 source package in Focal:
Fix Released
Status in linux source package in Hirsute:
In Progress
Status in linux-oem-5.10 source package in Hirsute:
Invalid
Status in linux-oem-5.13 source package in Hirsute:
Invalid
Status in linux source package in Impish:
In Progress
Status in linux-oem-5.10 source package in Impish:
Invalid
Status in linux-oem-5.13 source package in Impish:
Invalid

Bug description:
[Impact]
After hot-plug the Ethernet cable, the status of Ethernet is always down.

[Fix]
Because ASPM is enabled on RTL8106E, the link change interrupt can't be fired immediately.
Must wait a long time to get the link change interrupt.
After discuss with maintainer, he give some suggestions
1. use PHY_POLL.
2. he send a workaround(Ref. [1]) to disable ASPM on RTL8106E.

For 2, because don't know the details about operated registers in
rtl_hw_aspm_clkreq_enable, it have higher risk on power usage during
suspend.

For 1, Use PHY_POLL have a lower risk because don't change any register operations and use polling method to query link change status.
SRU the patches for 1 first.

Currently keep discussing with Realtek but don't figure out yet.
Will re-SRU the official solution once Realtek resolve the issue.

Ref [1], https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-
next.git/commit/?id=1ee8856de82faec9bc8bd0f2308a7f27e30ba207

[Test]
Verified on machines with Realtek Ethernet device, the Ethernet works well after hotplug 30 times.

[Regression Potential]
Medium, use polling methond may have higher cpu usage.

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