[REGRESSION] e1000e: RX stops after link down/up on Intel 8086:550a since v6.12.43 (fixed by suspend/resume)

["Wenger Jeremie (EDU)" <jeremie.wenger@edu.ge.ch>]

Hello,

I would like to report a regression in the e1000e driver affecting an Intel integrated Ethernet controller.

Hardware:
Intel Ethernet controller  [8086:550a]
Driver: e1000e

Summary:
- RX stops working after an Ethernet link down/up (unplug/replug cable).
- TX still works. A system suspend/resume reliably restores RX.

Regression range:
- Working: v6.12.22
- Broken: v6.12.43 .. v6.18.3 (tested on Debian 12 backports, Debian 13, Debian sid). v6.18.3 is the most recent kernel tested so far, so the regression is likely still present in newer kernels.
 
Symptoms:
- Link is detected (1Gbps, full duplex).
- DHCP DISCOVER frames are transmitted (confirmed via external packet capture).
- No packets are received (no DHCP OFFER, RX appears dead).
- Booting with the cable plugged works.
- The issue is triggered only after unplugging and replugging the cable.
- A suspend/resume cycle restores RX immediately.
- Using a USB Ethernet adapter (r8152) on the same network works correctly.
 
Reproduction steps:
- Boot with Ethernet cable plugged.
- Verify network connectivity works.
- Unplug the Ethernet cable.
- Plug the Ethernet cable back in.
- Observe that RX no longer works (no DHCP OFFER).
- Suspend/resume the system → RX works again.
 
This suggests that the PHY or RX path is not correctly reinitialized on link up after a link down event, while the resume path performs a more complete reset.

I can provide additional logs, ethtool statistics, or test patches if needed.


Best regards,

Jérémie Wenger