net: dsa: sja1105: Empty the RX timestamping queue on PTP settings change

When disabling PTP timestamping, don't reset the switch with the new
static config until all existing PTP frames have been timestamped on the
RX path or dropped. There's nothing we can do with these afterwards.

Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/sja1105/sja1105_ptp.c b/drivers/net/dsa/sja1105/sja1105_ptp.c
index 387b22a..e6b6114 100644
--- a/drivers/net/dsa/sja1105/sja1105_ptp.c
+++ b/drivers/net/dsa/sja1105/sja1105_ptp.c
@@ -83,6 +83,7 @@
 static int sja1105_change_rxtstamping(struct sja1105_private *priv,
 				      bool on)
 {
+	struct sja1105_ptp_data *ptp_data = &priv->ptp_data;
 	struct sja1105_general_params_entry *general_params;
 	struct sja1105_table *table;
 	int rc;
@@ -101,6 +102,8 @@
 		kfree_skb(priv->tagger_data.stampable_skb);
 		priv->tagger_data.stampable_skb = NULL;
 	}
+	ptp_cancel_worker_sync(ptp_data->clock);
+	skb_queue_purge(&ptp_data->skb_rxtstamp_queue);
 
 	return sja1105_static_config_reload(priv, SJA1105_RX_HWTSTAMPING);
 }