e1000e: add system to disable K1 list

Javier reports seeing packet loss issues related to the re-enablement
of K1; disabling it makes the issues go away. Add the reported system
to have K1 disabled by default.

Reproduction steps (from the Link):
Plug the cable and ping the default gateway on the LAN. No suspend/resume
involved, machine freshly booted and on AC power. Nothing e1000e-related in
dmesg apart from the link up/down messages; no "Hardware Unit Hang".

Default (K1 enabled):

  $ ping -c 30 192.168.10.1
  --- 192.168.10.1 ping statistics ---
  30 packets transmitted, 18 received, 40% packet loss, time 29734ms
  rtt min/avg/max/mdev = 0.211/0.315/0.384/0.046 ms

The lost packets are spread over the run (seq 6, 8, 9, 11, 13, 14, 16, 19,
20, 24, 25, 30), not a single burst. DHCP on this link also takes 1-2
minutes to get a lease, consistent with incoming packets being dropped.

With K1 disabled at runtime:

  # ethtool --set-priv-flags enp0s31f6 disable-k1 on
  $ ethtool --show-priv-flags enp0s31f6
  Private flags for enp0s31f6:
  s0ix-enabled: on
  disable-k1  : on

  $ ping -c 30 192.168.10.1
  --- 192.168.10.1 ping statistics ---
  30 packets transmitted, 30 received, 0% packet loss, time 29713ms
  rtt min/avg/max/mdev = 0.169/0.251/0.468/0.054 ms

  $ ping -c 30 192.168.10.1
  --- 192.168.10.1 ping statistics ---
  30 packets transmitted, 30 received, 0% packet loss, time 29677ms
  rtt min/avg/max/mdev = 0.101/0.222/0.360/0.064 ms

I have only compile tested this, but Javier has tested that disabling K1
on his system (Lenovo ThinkPad P14s Gen 5 (Intel), I219-LM [8086:550a])
resolves his issues.

Cc: stable@vger.kernel.org
Fixes: 578294b8b60d ("e1000e: Reconfigure PLL clock gate timeout and re-enable K1 on Meteor Lake")
Reported-by: Javier Herrera <javier.herrera@afronta.com>
Link: https://lore.kernel.org/intel-wired-lan/CAKRuCQLWEcci9hPgNUmvq44Bd2H30T5_vP=exMjsknXMN5Yh9A@mail.gmail.com/
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20261001222443.3500206-7-anthony.l.nguyen@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions