iwlwifi: handle unicast PS buffering

Using the new mac80211 functionality, this makes
iwlwifi handle unicast PS buffering correctly.
The device works like this:

 * when a station goes to sleep, the microcode notices
   this and marks the station as asleep
 * when the station is marked asleep, the microcode
   refuses to transmit to the station and rejects all
   frames queued to it with the failure status code
   TX_STATUS_FAIL_DEST_PS (a previous patch handled
   this correctly)
 * when we need to send frames to the station _although_
   it is asleep, we need to tell the ucode how many,
   and this is asynchronous with sending so we cannot
   just send the frames, we need to wait for all other
   frames to be flushed, and then update the counter
   before sending out the poll response frames. This
   is handled partially in the driver and partially in
   mac80211.

In order to do all this correctly, we need to
 * keep track of how many frames are pending for each
   associated client station (avoid doing it for other
   stations to avoid the atomic ops)
 * tell mac80211 that we driver-block the PS status
   while there are still frames pending on the queues,
   and once they are all rejected (due to the dest sta
   being in PS) unblock mac80211

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 50 insertions, 1 deletions

diff --git a/drivers/net/wireless/iwlwifi/iwl-tx.c b/drivers/net/wireless/iwlwifi/iwl-tx.c
index 9370e062000d..ebfc460115d6 100644
--- a/drivers/net/wireless/iwlwifi/iwl-tx.c
+++ b/drivers/net/wireless/iwlwifi/iwl-tx.c
@@ -709,6 +709,8 @@ int iwl_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
 {
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+	struct ieee80211_sta *sta = info->control.sta;
+	struct iwl_station_priv *sta_priv = NULL;
 	struct iwl_tx_queue *txq;
 	struct iwl_queue *q;
 	struct iwl_device_cmd *out_cmd;
@@ -771,6 +773,24 @@ int iwl_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
 
 	IWL_DEBUG_TX(priv, "station Id %d\n", sta_id);
 
+	if (sta)
+		sta_priv = (void *)sta->drv_priv;
+
+	if (sta_priv && sta_id != priv->hw_params.bcast_sta_id &&
+	    sta_priv->asleep) {
+		WARN_ON(!(info->flags & IEEE80211_TX_CTL_PSPOLL_RESPONSE));
+		/*
+		 * This sends an asynchronous command to the device,
+		 * but we can rely on it being processed before the
+		 * next frame is processed -- and the next frame to
+		 * this station is the one that will consume this
+		 * counter.
+		 * For now set the counter to just 1 since we do not
+		 * support uAPSD yet.
+		 */
+		iwl_sta_modify_sleep_tx_count(priv, sta_id, 1);
+	}
+
 	txq_id = skb_get_queue_mapping(skb);
 	if (ieee80211_is_data_qos(fc)) {
 		qc = ieee80211_get_qos_ctl(hdr);
@@ -930,6 +950,17 @@ int iwl_tx_skb(struct iwl_priv *priv, struct sk_buff *skb)
 	ret = iwl_txq_update_write_ptr(priv, txq);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
+	/*
+	 * At this point the frame is "transmitted" successfully
+	 * and we will get a TX status notification eventually,
+	 * regardless of the value of ret. "ret" only indicates
+	 * whether or not we should update the write pointer.
+	 */
+
+	/* avoid atomic ops if it isn't an associated client */
+	if (sta_priv && sta_priv->client)
+		atomic_inc(&sta_priv->pending_frames);
+
 	if (ret)
 		return ret;
 
@@ -1074,6 +1105,24 @@ int iwl_enqueue_hcmd(struct iwl_priv *priv, struct iwl_host_cmd *cmd)
 	return ret ? ret : idx;
 }
 
+static void iwl_tx_status(struct iwl_priv *priv, struct sk_buff *skb)
+{
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	struct ieee80211_sta *sta;
+	struct iwl_station_priv *sta_priv;
+
+	sta = ieee80211_find_sta(priv->vif, hdr->addr1);
+	if (sta) {
+		sta_priv = (void *)sta->drv_priv;
+		/* avoid atomic ops if this isn't a client */
+		if (sta_priv->client &&
+		    atomic_dec_return(&sta_priv->pending_frames) == 0)
+			ieee80211_sta_block_awake(priv->hw, sta, false);
+	}
+
+	ieee80211_tx_status_irqsafe(priv->hw, skb);
+}
+
 int iwl_tx_queue_reclaim(struct iwl_priv *priv, int txq_id, int index)
 {
 	struct iwl_tx_queue *txq = &priv->txq[txq_id];
@@ -1093,7 +1142,7 @@ int iwl_tx_queue_reclaim(struct iwl_priv *priv, int txq_id, int index)
 	     q->read_ptr = iwl_queue_inc_wrap(q->read_ptr, q->n_bd)) {
 
 		tx_info = &txq->txb[txq->q.read_ptr];
-		ieee80211_tx_status_irqsafe(priv->hw, tx_info->skb[0]);
+		iwl_tx_status(priv, tx_info->skb[0]);
 		tx_info->skb[0] = NULL;
 
 		if (priv->cfg->ops->lib->txq_inval_byte_cnt_tbl)