Re: [PATCH iwl-net v2] e1000e: restore jumbo config after DMoff exit

[Matt Vollrath <tactii@gmail.com>]

On 9/28/26 13:02, Craig I. Hagan wrote:
> 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: 2e7256f12cdb ("e1000e: Check the PCIm state")

Wasn't this bug introduced in def4ec6dce39 ? The more recent commit seems
like it just adds a pre-condition for the DMoff workaround. Tagging that
commit could cause stable to miss backport to 5.10.

Otherwise:

Reviewed-by: Matt Vollrath <tactii@gmail.com>
Tested-by: Matt Vollrath <tactii@gmail.com>

> 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>
> Assisted-by: LLM
> Signed-off-by: Craig I. Hagan <hagan@amazon.com>
> ---
> v2: Rework per review. Instead of the fc-latch autoneg-restart
>      approach, 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;
> +					}
>   				}
>   			}
>