[PATCH iwl-net 0/4] ice: fix PTP timestamp handling issues

[Przemyslaw Korba <przemyslaw.korba@intel.com>]

This series fixes several PTP timestamp handling issues in the ice
driver that manifest during link state transitions on E82x devices.
Together, these issues can cause Tx timestamp timeouts, ptp4l service
disruptions, and on PREEMPT_RT kernels, a system livelock requiring a
hard reboot.

The root cause is a set of race conditions in the PTP link change path.
When taking the link down (ice_down) or bringing it up
(ice_up_complete), the PTP recalibration and cleanup were not properly
synchronized with actual physical link transitions. This allowed Tx
timestamp requests to be queued against uncalibrated or stopped PHY
hardware, producing orphaned timestamp ready bits in the PHY registers.

On E82x, the PHY will not generate a new timestamp interrupt until all
outstanding ready bits have been read. Orphaned bits — set for slots
with no matching software tracker entry — are never read, permanently
blocking new timestamp interrupts. The existing periodic work detects
this symptom and re-triggers the interrupt, but without clearing the
stale bits, this creates an infinite trigger loop. On PREEMPT_RT
kernels, the resulting interrupt storm causes RCU stalls and eventually
a full system livelock.

Arkadiusz Kubalewski (1):
  ice: call PTP link change only from link events

Jacob Keller (1):
  ice: clear unexpected Tx timestamp ready bits to prevent stuck PHY

Karol Kolacinski (2):
  ice: keep Tx timestamps disabled until offset calibration completes
  ice: cancel E82x offset verification work during reset preparation

 drivers/net/ethernet/intel/ice/ice_main.c   |   3 +-
 drivers/net/ethernet/intel/ice/ice_ptp.c    | 155 +++++++++++++++++---
 drivers/net/ethernet/intel/ice/ice_ptp_hw.c |  89 +++++++++--
 drivers/net/ethernet/intel/ice/ice_ptp_hw.h |   1 +
 drivers/net/ethernet/intel/ice/ice_type.h   |   7 +
 5 files changed, 219 insertions(+), 36 deletions(-)

-- 
2.43.0