iwlwifi: mvm: don't send the IWL_MVM_RXQ_NSSN_SYNC notif to Rx queues

commit d829229e35f302fd49c052b5c5906c90ecf9911d upstream.

The purpose of this was to keep all the queues updated with
the Rx sequence numbers because unlikely yet possible
situations where queues can't understand if a specific
packet needs to be dropped or not.

Unfortunately, it was reported that this caused issues in
our DMA engine. We don't fully understand how this is related,
but this is being currently debugged. For now, just don't send
this notification to the Rx queues. This de-facto reverts my
commit 3c514bf831ac12356b695ff054bef641b9e99593:

iwlwifi: mvm: add a loose synchronization of the NSSN across Rx queues

This issue was reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=204873
https://bugzilla.kernel.org/show_bug.cgi?id=205001
and others maybe.

Fixes: 3c514bf831ac ("iwlwifi: mvm: add a loose synchronization of the NSSN across Rx queues")
CC: <stable@vger.kernel.org> # 5.3+
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/constants.h b/drivers/net/wireless/intel/iwlwifi/mvm/constants.h
index 60aff2e..58df25e 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/mvm/constants.h
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/constants.h
@@ -154,5 +154,6 @@
 #define IWL_MVM_D3_DEBUG                       false
 #define IWL_MVM_USE_TWT                                false
 #define IWL_MVM_AMPDU_CONSEC_DROPS_DELBA       10
+#define IWL_MVM_USE_NSSN_SYNC                  0
 
 #endif /* __MVM_CONSTANTS_H */

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
index 77b03b7..a6e2a30 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c
@@ -514,14 +514,17 @@ static bool iwl_mvm_is_sn_less(u16 sn1, u16 sn2, u16 buffer_size)
 
 static void iwl_mvm_sync_nssn(struct iwl_mvm *mvm, u8 baid, u16 nssn)
 {
-       struct iwl_mvm_rss_sync_notif notif = {
-               .metadata.type = IWL_MVM_RXQ_NSSN_SYNC,
-               .metadata.sync = 0,
-               .nssn_sync.baid = baid,
-               .nssn_sync.nssn = nssn,
-       };
-
-       iwl_mvm_sync_rx_queues_internal(mvm, (void *)&notif, sizeof(notif));
+       if (IWL_MVM_USE_NSSN_SYNC) {
+               struct iwl_mvm_rss_sync_notif notif = {
+                       .metadata.type = IWL_MVM_RXQ_NSSN_SYNC,
+                       .metadata.sync = 0,
+                       .nssn_sync.baid = baid,
+                       .nssn_sync.nssn = nssn,
+               };
+
+               iwl_mvm_sync_rx_queues_internal(mvm, (void *)&notif,
+                                               sizeof(notif));
+       }
 }
 
 #define RX_REORDER_BUF_TIMEOUT_MQ (HZ / 10)