Re: [PATCH net] ice: fix PTP hang for E825C devices

[Simon Horman <horms@kernel.org>]

On Fri, Mar 27, 2026 at 08:23:27AM +0100, Aleksandr Loktionov wrote:
> From: Grzegorz Nitka <grzegorz.nitka@intel.com>
> 
> Change the order of PTP reconfiguration when port goes down or up
> (ice_down and ice_up calls) to be more graceful and consistent from
> timestamp interrupts processing perspective.
> 
> For both calls (ice_up and ice_down), accompanying ice_ptp_link_change
> is called which starts/stops PTP timer. This patch changes the order:
> - while link goes down: disable net device Tx first (netif_carrier_off,
>   netif_tx_disable), then call ice_ptp_link_change
> - while link goes up: ice_ptp_link_change called first, then re-enable
>   net device Tx (netif_tx_start_all_queues)
> 
> Otherwise, there is a narrow window in which PTP timestamp request has
> been triggered and timestamp processing occurs when PTP timer is not
> enabled yet (up case) or already disabled (down case). This may lead to
> undefined behavior and receiving invalid timestamps. This case was
> observed on E825C devices only.
> 
> Fixes: 6b1ff5d39228 ("ice: always call ice_ptp_link_change and make it void")
> Cc: stable@vger.kernel.org
> Signed-off-by: Grzegorz Nitka <grzegorz.nitka@intel.com>
> Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>