[PATCH net 10/15] ice: wait for in-flight Tx timestamps before flushing the tracker

[Tony Nguyen <anthony.l.nguyen@intel.com>]

From: Petr Oros <poros@redhat.com>

ice_ptp_flush_tx_tracker() frees every tracked request, but a request
whose timestamp is still being captured by the PHY at that moment is
freed without touching the PHY entry. The ready bit published shortly
after has no tracked owner, and the PHY does not raise another Tx
timestamp interrupt until every outstanding ready bit is read, so
delivery for the whole quad degrades to the periodic work.

Wait up to 10 ms for in-flight captures to publish their ready bits
before flushing, so the flush clears them together with the rest.

Fixes: ea9b847cda64 ("ice: enable transmit timestamps for E810 devices")
Signed-off-by: Petr Oros <poros@redhat.com>
Reviewed-by: Maciek Machnikowski <maciej.machnikowski@intel.com>
Tested-by: Alexander Nowlin <alexander.nowlin@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
 drivers/net/ethernet/intel/ice/ice_ptp.c | 33 ++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/net/ethernet/intel/ice/ice_ptp.c b/drivers/net/ethernet/intel/ice/ice_ptp.c
index 4dec728e219d..b142b779dc10 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp.c
@@ -740,6 +740,37 @@ ice_ptp_alloc_tx_tracker(struct ice_ptp_tx *tx)
 	return 0;
 }
 
+static void
+ice_ptp_wait_for_tracker_drain(struct ice_pf *pf, struct ice_ptp_tx *tx)
+{
+	unsigned long deadline = jiffies + msecs_to_jiffies(10);
+	struct ice_hw *hw = &pf->hw;
+	u64 tstamp_ready;
+	bool pending;
+	u8 idx;
+
+	if (hw->reset_ongoing)
+		return;
+
+	do {
+		if (ice_get_phy_tx_tstamp_ready(hw, tx->block, &tstamp_ready))
+			return;
+
+		pending = false;
+		for_each_set_bit(idx, tx->in_use, tx->len) {
+			if (!(tstamp_ready & BIT_ULL(idx + tx->offset)))
+				pending = true;
+		}
+		if (!pending)
+			return;
+
+		usleep_range(500, 1000);
+	} while (time_before(jiffies, deadline));
+
+	dev_dbg(ice_pf_to_dev(pf), "Timed out waiting for in-flight Tx timestamps on block %u\n",
+		tx->block);
+}
+
 /**
  * ice_ptp_flush_tx_tracker - Flush any remaining timestamps from the tracker
  * @pf: Board private structure
@@ -756,6 +787,8 @@ ice_ptp_flush_tx_tracker(struct ice_pf *pf, struct ice_ptp_tx *tx)
 	int err;
 	u8 idx;
 
+	ice_ptp_wait_for_tracker_drain(pf, tx);
+
 	err = ice_get_phy_tx_tstamp_ready(hw, tx->block, &tstamp_ready);
 	if (err) {
 		dev_dbg(ice_pf_to_dev(pf), "Failed to get the Tx tstamp ready bitmap for block %u, err %d\n",
-- 
2.47.1