> -----Original Message-----
> From: Jacob Keller <[email protected]>
> Sent: Friday, September 25, 2026 4:57 PM
> To: Intel Wired LAN <[email protected]>; Machnikowski, Maciej
> <[email protected]>; Keller, Jacob E <[email protected]>;
> Korba, Przemyslaw <[email protected]>; Nguyen, Anthony L
> <[email protected]>; Nitka, Grzegorz <[email protected]>;
> Kubalewski, Arkadiusz <[email protected]>
> Cc: Keller, Jacob E <[email protected]>; Oros, Petr
> <[email protected]>; Machnikowski, Maciej <[email protected]>
> Subject: [PATCH iwl-net v3 12/15] ice: keep Tx timestamp slots tracked until
> completion or timeout
>
> From: Petr Oros <[email protected]>
>
> When the link goes down the processing loop drops every outstanding request,
> and a request whose timestamp is not ready yet is freed without reading the
> PHY slot. The hardware completes the capture a moment later, the orphaned
> ready bit blocks the port interrupt until the next link-up sweep, and the
> freed index can meanwhile be reused by a new request whose slot the hardware
> then overwrites. Captured on a reproducer as ready bits with no in_use owner
> right after a link bounce.
>
> Stop dropping on link down. Mark the outstanding requests stale so their
> completions are read and discarded, reject new requests while the link is
> down, and free a not yet ready slot only after the two second timeout. This
> way an index is never reused while the hardware can still write it and never
> left untracked while a completion can still arrive.
>
> Since we're adding a new call to ice_ptp_mark_tx_tracker, notice that the
> function previously did not check the tracker initialization state. Fix this
> by only accessing the bitmaps if the init field is set.
>
> To avoid continuously re-triggering the IRQ at the end of a processing loop
> when we have a stale packet that is not timestamped, modify
> ice_ptp_tx_tstamps_pending() to ignore stale timestamps when checking for
> whether to re-arm the IRQ from the miscellaneous thread function. Instead,
> only count stale packets as part of the check in the auxiliary work thread.
> This way we do not keep spamming the IRQ when the timestamp won't be reported
> anyways.
>
> To ensure that forward progress is made on clearing stale timestamps, fix the
> check for ice_ptp_maybe_trigger_tx_interrupt to properly apply for devices
> that manage their own interrupt, instead of only checking on the clock owner.
> In the case of a timestamp which never completes, this does result in one
> extra IRQ every 500 msec until the timeout. In some sense this is extra work,
> but we need to recheck to ensure that timestamp slots do not remain locked
> forever, and the software can't reliably know whether a given index will or
> won't complete.
>
> Note that E810 does not have the ready bitmap in its hardware. It is
> currently excluded from the ice_ptp_maybe_trigger_tx_interrupt() by a check
> against the has_ready_bitmap field. This could lead to an interrupt stall if
> every single Tx timestamp index slot becomes stale. However, just removing
> the check against has_ready_bitmap would be problematic for the low latency
> path which currently is not protected against another IRQ happening while a
> request is outstanding. That is a pre-existing issue, but we should avoid
> making it worse until the path can be addressed by another fix. The low
> latency path also completely > bypasses the
> ice_ptp_process_tx_tstamp() flow. For now, skip the
> ice_ptp_maybe_trigger_tx_interrupt() when ts_ll_int_read is set and the low
> latency path is in use. The path still has preexisting issues but this avoids
> making it worse.
> This effectively reverts commit fcc2cef37fed ("ice/ptp: fix the PTP worker
> retrying indefinitely if the link went down"), which tried to release an
> index before this 2 second wait period.
> Fixes: fcc2cef37fed ("ice/ptp: fix the PTP worker retrying indefinitely if
> the link went down")
> Suggested-by: Jacob Keller <[email protected]>
> Signed-off-by: Petr Oros <[email protected]>
> Reviewed-by: Maciek Machnikowski <[email protected]>
> Signed-off-by: Jacob Keller <[email protected]>
> ---
> drivers/net/ethernet/intel/ice/ice_ptp.h | 8 +++--
> drivers/net/ethernet/intel/ice/ice_main.c | 2 +-
> drivers/net/ethernet/intel/ice/ice_ptp.c | 57 ++++++++++++++++---------------
> 3 files changed, 37 insertions(+), 30 deletions(-)
Tested-by: Alexander Nowlin <[email protected]>
