iwlagn: move the check_empty logic to the transport layer

This logic is responsible to tell mac80211 when the HW queues are
empty and the BA session can be started / torn down.

Fix a bug on the way:
When the the Tx BA session is stopped and the HW queues aren't empty,
we stop the SW queue to drain the HW queue and then switch to the
legacy HW queue. This is the IWL_EMPTYING_HW_QUEUE_DELBA state.

While in this state, we never wake the SW queue, even when the HW
queue is almost empty, since we need to drain it completely. Look
at iwl_trans_pcie_reclaim regarding this.

Once the HW queue is really empty, we must wake the SW queue in order
to get traffic to the legacy queue.
This step was missing leading to an odd situation were the traffic
would just stall after we tore down a Tx BA session while the HW
queue was not empty.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 66 insertions, 7 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-trans.c b/drivers/net/wireless/iwlwifi/iwl-trans.c
index 13e8fdc4c01..0256454427f 100644
--- a/drivers/net/wireless/iwlwifi/iwl-trans.c
+++ b/drivers/net/wireless/iwlwifi/iwl-trans.c
@@ -1265,19 +1265,75 @@ static int iwl_trans_pcie_request_irq(struct iwl_trans *trans)
 	return 0;
 }
 
-static void iwl_trans_pcie_reclaim(struct iwl_trans *trans, int txq_id,
-		      int ssn, u32 status, struct sk_buff_head *skbs)
+static int iwlagn_txq_check_empty(struct iwl_trans *trans,
+			   int sta_id, u8 tid, int txq_id)
 {
-	struct iwl_priv *priv = priv(trans);
-	struct iwl_tx_queue *txq = &priv->txq[txq_id];
+	struct iwl_queue *q = &priv(trans)->txq[txq_id].q;
+	struct iwl_tid_data *tid_data = &trans->shrd->tid_data[sta_id][tid];
+
+	lockdep_assert_held(&trans->shrd->sta_lock);
+
+	switch (trans->shrd->tid_data[sta_id][tid].agg.state) {
+	case IWL_EMPTYING_HW_QUEUE_DELBA:
+		/* We are reclaiming the last packet of the */
+		/* aggregated HW queue */
+		if ((txq_id  == tid_data->agg.txq_id) &&
+		    (q->read_ptr == q->write_ptr)) {
+			IWL_DEBUG_HT(trans,
+				"HW queue empty: continue DELBA flow\n");
+			iwl_trans_pcie_txq_agg_disable(priv(trans), txq_id);
+			tid_data->agg.state = IWL_AGG_OFF;
+			iwl_stop_tx_ba_trans_ready(priv(trans),
+						   NUM_IWL_RXON_CTX,
+						   sta_id, tid);
+			iwl_wake_queue(priv(trans), &priv(trans)->txq[txq_id]);
+		}
+		break;
+	case IWL_EMPTYING_HW_QUEUE_ADDBA:
+		/* We are reclaiming the last packet of the queue */
+		if (tid_data->tfds_in_queue == 0) {
+			IWL_DEBUG_HT(trans,
+				"HW queue empty: continue ADDBA flow\n");
+			tid_data->agg.state = IWL_AGG_ON;
+			iwl_start_tx_ba_trans_ready(priv(trans),
+						    NUM_IWL_RXON_CTX,
+						    sta_id, tid);
+		}
+		break;
+	}
+
+	return 0;
+}
+
+static void iwl_free_tfds_in_queue(struct iwl_trans *trans,
+			    int sta_id, int tid, int freed)
+{
+	lockdep_assert_held(&trans->shrd->sta_lock);
+
+	if (trans->shrd->tid_data[sta_id][tid].tfds_in_queue >= freed)
+		trans->shrd->tid_data[sta_id][tid].tfds_in_queue -= freed;
+	else {
+		IWL_DEBUG_TX(trans, "free more than tfds_in_queue (%u:%d)\n",
+			trans->shrd->tid_data[sta_id][tid].tfds_in_queue,
+			freed);
+		trans->shrd->tid_data[sta_id][tid].tfds_in_queue = 0;
+	}
+}
+
+static void iwl_trans_pcie_reclaim(struct iwl_trans *trans, int sta_id, int tid,
+		      int txq_id, int ssn, u32 status,
+		      struct sk_buff_head *skbs)
+{
+	struct iwl_tx_queue *txq = &priv(trans)->txq[txq_id];
 	/* n_bd is usually 256 => n_bd - 1 = 0xff */
 	int tfd_num = ssn & (txq->q.n_bd - 1);
+	int freed = 0;
 	u8 agg_state;
 	bool cond;
 
 	if (txq->sched_retry) {
 		agg_state =
-			priv->shrd->tid_data[txq->sta_id][txq->tid].agg.state;
+			trans->shrd->tid_data[txq->sta_id][txq->tid].agg.state;
 		cond = (agg_state != IWL_EMPTYING_HW_QUEUE_DELBA);
 	} else {
 		cond = (status != TX_STATUS_FAIL_PASSIVE_NO_RX);
@@ -1287,10 +1343,13 @@ static void iwl_trans_pcie_reclaim(struct iwl_trans *trans, int txq_id,
 		IWL_DEBUG_TX_REPLY(trans, "Retry scheduler reclaim "
 				"scd_ssn=%d idx=%d txq=%d swq=%d\n",
 				ssn , tfd_num, txq_id, txq->swq_id);
-		iwl_tx_queue_reclaim(trans, txq_id, tfd_num, skbs);
+		freed = iwl_tx_queue_reclaim(trans, txq_id, tfd_num, skbs);
 		if (iwl_queue_space(&txq->q) > txq->q.low_mark && cond)
-			iwl_wake_queue(priv, txq);
+			iwl_wake_queue(priv(trans), txq);
 	}
+
+	iwl_free_tfds_in_queue(trans, sta_id, tid, freed);
+	iwlagn_txq_check_empty(trans, sta_id, tid, txq_id);
 }
 
 static void iwl_trans_pcie_free(struct iwl_trans *trans)