wifi: iwlwifi: disable multi rx queue for 9000

Multi rx queue allows to spread the load of the Rx streams on different
CPUs. 9000 series required complex synchronization mechanisms from the
driver side since the hardware / firmware is not able to provide
information about duplicate packets and timeouts inside the reordering
buffer.

Users have complained that for newer devices, all those synchronization
mechanisms have caused spurious packet drops. Those packet drops
disappeared if we simplify the code, but unfortunately, we can't have
RSS enabled on 9000 series without this complex code.

Remove support for RSS on 9000 so that we can make the code much simpler
for newer devices and fix the bugs for them.

The down side of this patch is a that all the Rx path will be routed to
a single CPU, but this has never been an issue, the modern CPUs are just
fast enough to cope with all the traffic.

Signed-off-by: Emmanuel Grumbach <[email protected]>
Signed-off-by: Gregory Greenman <[email protected]>
Link: https://lore.kernel.org/r/20231017115047.2917eb8b7af9.Iddd7dcf335387ba46fcbbb6067ef4ff9cd3755a7@changeid
Signed-off-by: Johannes Berg <[email protected]>

Author: egrumbach

drivers/net/wireless/intel/iwlwifi/iwl-trans.h

@@ -279,7 +279,7 @@ static inline void iwl_free_rxb(struct iwl_rx_cmd_buffer *r)
 #define IWL_MGMT_TID		15
 #define IWL_FRAME_LIMIT	64
 #define IWL_MAX_RX_HW_QUEUES	16
-#define IWL_9000_MAX_RX_HW_QUEUES	6
+#define IWL_9000_MAX_RX_HW_QUEUES	1
 
 /**
  * enum iwl_wowlan_status - WoWLAN image/device status

drivers/net/wireless/intel/iwlwifi/mvm/mac80211.c

@@ -376,7 +376,9 @@ int iwl_mvm_mac_setup_register(struct iwl_mvm *mvm)
 		ieee80211_hw_set(hw, HAS_RATE_CONTROL);
 	}
 
-	if (iwl_mvm_has_new_rx_api(mvm))
+	/* We want to use the mac80211's reorder buffer for 9000 */
+	if (iwl_mvm_has_new_rx_api(mvm) &&
+	    mvm->trans->trans_cfg->device_family > IWL_DEVICE_FAMILY_9000)
 		ieee80211_hw_set(hw, SUPPORTS_REORDERING_BUFFER);
 
 	if (fw_has_capa(&mvm->fw->ucode_capa,

drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c

@@ -957,6 +957,9 @@ static bool iwl_mvm_reorder(struct iwl_mvm *mvm,
 	baid = (reorder & IWL_RX_MPDU_REORDER_BAID_MASK) >>
 		IWL_RX_MPDU_REORDER_BAID_SHIFT;
 
+	if (mvm->trans->trans_cfg->device_family == IWL_DEVICE_FAMILY_9000)
+		return false;
+
 	/*
 	 * This also covers the case of receiving a Block Ack Request
 	 * outside a BA session; we'll pass it to mac80211 and that
@@ -2617,9 +2620,15 @@ void iwl_mvm_rx_mpdu_mq(struct iwl_mvm *mvm, struct napi_struct *napi,
 
 	if (!iwl_mvm_reorder(mvm, napi, queue, sta, skb, desc) &&
 	    likely(!iwl_mvm_time_sync_frame(mvm, skb, hdr->addr2)) &&
-	    likely(!iwl_mvm_mei_filter_scan(mvm, skb)))
+	    likely(!iwl_mvm_mei_filter_scan(mvm, skb))) {
+		if (mvm->trans->trans_cfg->device_family == IWL_DEVICE_FAMILY_9000 &&
+		    (desc->mac_flags2 & IWL_RX_MPDU_MFLG2_AMSDU) &&
+		    !(desc->amsdu_info & IWL_RX_MPDU_AMSDU_LAST_SUBFRAME))
+			rx_status->flag |= RX_FLAG_AMSDU_MORE;
+
 		iwl_mvm_pass_packet_to_mac80211(mvm, napi, skb, queue, sta,
 						link_sta);
+	}
 out:
 	rcu_read_unlock();
 }