iwlwifi: mvm: give client MACs time to synchronise during restart

When firmware restart happens, the timers are obviously reset and
the new firmware has no synchronisation with the AP as we program
timings to the pre-restart values. The firmware should attempt to
synchronise by itself, but in multi-channel scenarios this isn't
easy, particularly since it has to try to keep service quality up
for other MACs.

To make it more reliable, give each client MAC some time to catch
beacons when restarting or resuming. Service quality was impacted
anyway (or in resume doesn't really matter much.)

Reviewed-by: Moshe Island <moshe.island@intel.com>
Reviewed-by: Ilan Peer <ilan.peer@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/iwlwifi/mvm/mac80211.c
index 3261730181fa..77166520bc01 100644
--- a/drivers/net/wireless/iwlwifi/mvm/mac80211.c
+++ b/drivers/net/wireless/iwlwifi/mvm/mac80211.c
@@ -803,6 +803,27 @@ static void iwl_mvm_bss_info_changed_station(struct iwl_mvm *mvm,
 				return;
 			}
 			iwl_mvm_configure_mcast_filter(mvm, vif);
+
+			if (test_bit(IWL_MVM_STATUS_IN_HW_RESTART,
+				     &mvm->status)) {
+				/*
+				 * If we're restarting then the firmware will
+				 * obviously have lost synchronisation with
+				 * the AP. It will attempt to synchronise by
+				 * itself, but we can make it more reliable by
+				 * scheduling a session protection time event.
+				 *
+				 * The firmware needs to receive a beacon to
+				 * catch up with synchronisation, use 110% of
+				 * the beacon interval.
+				 *
+				 * Set a large maximum delay to allow for more
+				 * than a single interface.
+				 */
+				u32 dur = (11 * vif->bss_conf.beacon_int) / 10;
+				iwl_mvm_protect_session(mvm, vif, dur, dur,
+							5 * dur);
+			}
 		} else if (mvmvif->ap_sta_id != IWL_MVM_STATION_COUNT) {
 			/* remove AP station now that the MAC is unassoc */
 			ret = iwl_mvm_rm_sta_id(mvm, vif, mvmvif->ap_sta_id);
@@ -1170,7 +1191,7 @@ static void iwl_mvm_mac_mgd_prepare_tx(struct ieee80211_hw *hw,
 
 	mutex_lock(&mvm->mutex);
 	/* Try really hard to protect the session and hear a beacon */
-	iwl_mvm_protect_session(mvm, vif, duration, min_duration);
+	iwl_mvm_protect_session(mvm, vif, duration, min_duration, 500);
 	mutex_unlock(&mvm->mutex);
 }