[Bug 1809847] Re: Ethernet[10ec:8136] doesn't work after S3 with kernel 4.15.0.43.64

https://lists.ubuntu.com/archives/kernel-team/2018-December/097407.html

** Tags added: originate-from-1809705 somerville

** Changed in: linux (Ubuntu)
Status: In Progress => Fix Committed

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https://bugs.launchpad.net/bugs/1809847

Title:
Ethernet[10ec:8136] doesn't work after S3 with kernel 4.15.0.43.64

Status in HWE Next:
New
Status in linux package in Ubuntu:
Fix Committed

Bug description:
[Impact]
The Ethernet works after S3 with kernel 4.15.0-33.36, and fails with kernel 4.15.0.43.64.
There is no interrupt while plug/unplug Ethernet cable after S3, so it looks like a regression after 4.15.0-33.36.

[Fix]
Check changelog and found there are 2 commits introduced from 4.15.0-35.38 might be suspicious
  * r8169 no internet after suspending (LP: #1779817)
    - r8169: don't use MSI-X on RTL8168g
    - r8169: don't use MSI-X on RTL8106e
And check the upstream log and found the 2 MSI-X commits had been all reverted, since below commit claims it fixes the MSI-X interrupt issue which is already in Bionic kernel.
   083874549fdf PCI: Reprogram bridge prefetch registers on resume
So, I reverted the 2 MSI-X commits and found the Ethernet works again after S3.

[Regression Potential]
Low, the 2 disable MSI-X commits are workarounds, and now we have proper way to fix the issue, so it should be fine to revert them.

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