Subject: Re: [PATCH iwl-net] ice: restore PTP Rx timestamp config after ethtool set-channels

From: Simon Horman <[email-masked]>
Date: Sun, 10 May 2026 16:32:16 +0100

On Thu, May 07, 2026 at 10:16:53AM +0200, Grzegorz Nitka wrote:
> When ethtool -L changes queue counts, ice_vsi_recfg_qs() closes and
> rebuilds the VSI, reallocating Rx rings. The newly allocated rings have
> ptp_rx cleared, so RX hardware timestamps are no longer attached to skb
> until hwtstamp configuration is applied again.
> 
> Restore timestamp mode after ice_vsi_open() in the queue reconfiguration
> path, matching reset/rebuild behavior and ensuring newly rebuilt Rx rings
> have PTP RX timestamping re-enabled.
> 
> Testing hints:
> - run ptp4l application in client synchronization mode:
> 	 ptp4l -i ethX -m -s
> - run PTP traffic
> - change queue number on ethX netdev interface:
> 	ethtool -L ethX combined new_queue_size
> - observe ptp4l output
> - expected result: no "received DELAY_REQ without timestamp" messages
> 
> Fixes: 77a781155a65 ("ice: enable receive hardware timestamping")
> Cc: [email-masked]
> Reviewed-by: Aleksandr Loktionov <[email-masked]>
> Signed-off-by: Grzegorz Nitka <[email-masked]>

Reviewed-by: Simon Horman <[email-masked]>

FTR: There is an AI-generated review of this patch available on sashiko.dev.
     I do not believe any of the issues raised there should block progress
     of this patch.