[PATCH iwl-net v3] e1000e: restore jumbo config after DMoff exit

["Craig I. Hagan" <hagan@amazon.com>]

On an I219 (pch_spt+) at jumbo MTU, after a link partner reset (e.g. a
switch reboot) the interface can come back up unable to pass traffic until
it is manually reset. Observed on I219-LM (8086:15b7) at MTU 9000.

When the MAC exits the DMoff state on link-up, the watchdog resets only
the PHY. A bare PHY reset does not re-run the jumbo-frame workaround
(e1000_lv_jumbo_workaround_ich8lan), so the jumbo configuration is left
unapplied and traffic stalls. This was seen with NIC runtime PM disabled;
if runtime PM were enabled, the device should go through a full reset on
resume, avoiding this issue.

Request a full reset (FLAG_RESTART_NOW) instead of the bare PHY reset when
the MAC exits DMoff, so the normal reset path re-applies the jumbo-frame
configuration.

Fixes: def4ec6dce39 ("e1000e: PCIm function state support")
Cc: stable@vger.kernel.org
Reported-by: Fabio Sabai <sabfabio@amazon.com>
Closes: https://github.com/systemd/systemd/issues/25925
Suggested-by: Matt Vollrath <tactii@gmail.com>
Reviewed-by: Matt Vollrath <tactii@gmail.com>
Tested-by: Matt Vollrath <tactii@gmail.com>
Assisted-by: LLM
Signed-off-by: Craig I. Hagan <hagan@amazon.com>
---
v3: Correct the Fixes: tag to def4ec6dce39 ("e1000e: PCIm function
    state support"), which introduced the DMoff-exit bare PHY reset;
    2e7256f12cdb only added a pre-condition. This lets stable reach
    the affected trees (v5.3+, including 5.4/5.10). Add Reviewed-by/
    Tested-by from Matt Vollrath.
v2: Rework per review: request a full reset on DMoff exit so the
    jumbo-frame workaround is re-applied (root cause identified by
    Matt Vollrath); drop the diagnostic e_info. v1:
    https://lore.kernel.org/netdev/20260923235832.473-1-hagan@amazon.com/

 drivers/net/ethernet/intel/e1000e/netdev.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index 844f31ab3..df7da86a8 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5264,9 +5264,11 @@ static void e1000_watchdog_task(struct work_struct *work)
 					usleep_range(10000, 20000);
 					pcim_state = er32(STATUS);
 
-					/* Checking if MAC exited DMoff state */
-					if (!(pcim_state & E1000_STATUS_PCIM_STATE))
-						e1000_phy_hw_reset(&adapter->hw);
+					/* MAC exited DMoff; do a full reset. */
+					if (!(pcim_state & E1000_STATUS_PCIM_STATE)) {
+						adapter->flags |= FLAG_RESTART_NOW;
+						goto link_up;
+					}
 				}
 			}
 
-- 
2.47.3