mac80211: mesh power save basics

Add routines to
- maintain a PS mode for each peer and a non-peer PS mode
- indicate own PS mode in transmitted frames
- track neighbor STAs power modes
- buffer frames when neighbors are in PS mode
- add TIM and Awake Window IE to beacons
- release frames in Mesh Peer Service Periods

Add local_pm to sta_info to represent the link-specific power
mode at this station towards the remote station. When a peer
link is established, use the default power mode stored in mesh
config. Update the PS status if the peering status of a neighbor
changes.
Maintain a mesh power mode for non-peer mesh STAs. Set the
non-peer power mode to active mode during peering. Authenticated
mesh peering is currently not working when either node is
configured to be in power save mode.

Indicate the current power mode in transmitted frames. Use QoS
Nulls to indicate mesh power mode transitions.
For performance reasons, calls to the function setting the frame
flags are placed in HWMP routing routines, as there the STA
pointer is already available.

Add peer_pm to sta_info to represent the peer's link-specific
power mode towards the local station. Add nonpeer_pm to
represent the peer's power mode towards all non-peer stations.
Track power modes based on received frames.

Add the ps_data structure to ieee80211_if_mesh (for TIM map, PS
neighbor counter and group-addressed frame buffer).

Set WLAN_STA_PS flag for STA in PS mode to use the unicast frame
buffering routines in the tx path. Update num_sta_ps to buffer
and release group-addressed frames after DTIM beacons.

Announce the awake window duration in beacons if in light or
deep sleep mode towards any peer or non-peer. Create a TIM IE
similarly to AP mode and add it to mesh beacons. Parse received
Awake Window IEs and check TIM IEs for buffered frames.

Release frames towards peers in mesh Peer Service Periods. Use
the corresponding trigger frames and monitor the MPSP status.
Append a QoS Null as trigger frame if neccessary to properly end
the MPSP. Currently, in HT channels MPSPs behave imperfectly and
show large delay spikes and frame losses.

Signed-off-by: Marco Porsch <marco@cozybit.com>
Signed-off-by: Ivan Bezyazychnyy <ivan.bezyazychnyy@gmail.com>
Signed-off-by: Mike Krinkin <krinkin.m.u@gmail.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 585 insertions, 0 deletions

diff --git a/net/mac80211/mesh_ps.c b/net/mac80211/mesh_ps.c
new file mode 100644
index 00000000000..b677962525e
--- /dev/null
+++ b/net/mac80211/mesh_ps.c
@@ -0,0 +1,585 @@
+/*
+ * Copyright 2012-2013, Marco Porsch <marco.porsch@s2005.tu-chemnitz.de>
+ * Copyright 2012-2013, cozybit Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include "mesh.h"
+#include "wme.h"
+
+
+/* mesh PS management */
+
+/**
+ * mps_qos_null_get - create pre-addressed QoS Null frame for mesh powersave
+ */
+static struct sk_buff *mps_qos_null_get(struct sta_info *sta)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct ieee80211_local *local = sdata->local;
+	struct ieee80211_hdr *nullfunc; /* use 4addr header */
+	struct sk_buff *skb;
+	int size = sizeof(*nullfunc);
+	__le16 fc;
+
+	skb = dev_alloc_skb(local->hw.extra_tx_headroom + size + 2);
+	if (!skb)
+		return NULL;
+	skb_reserve(skb, local->hw.extra_tx_headroom);
+
+	nullfunc = (struct ieee80211_hdr *) skb_put(skb, size);
+	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_QOS_NULLFUNC);
+	ieee80211_fill_mesh_addresses(nullfunc, &fc, sta->sta.addr,
+				      sdata->vif.addr);
+	nullfunc->frame_control = fc;
+	nullfunc->duration_id = 0;
+	/* no address resolution for this frame -> set addr 1 immediately */
+	memcpy(nullfunc->addr1, sta->sta.addr, ETH_ALEN);
+	memset(skb_put(skb, 2), 0, 2); /* append QoS control field */
+	ieee80211_mps_set_frame_flags(sdata, sta, nullfunc);
+
+	return skb;
+}
+
+/**
+ * mps_qos_null_tx - send a QoS Null to indicate link-specific power mode
+ */
+static void mps_qos_null_tx(struct sta_info *sta)
+{
+	struct sk_buff *skb;
+
+	skb = mps_qos_null_get(sta);
+	if (!skb)
+		return;
+
+	mps_dbg(sta->sdata, "announcing peer-specific power mode to %pM\n",
+		sta->sta.addr);
+
+	/* don't unintentionally start a MPSP */
+	if (!test_sta_flag(sta, WLAN_STA_PS_STA)) {
+		u8 *qc = ieee80211_get_qos_ctl((void *) skb->data);
+
+		qc[0] |= IEEE80211_QOS_CTL_EOSP;
+	}
+
+	ieee80211_tx_skb(sta->sdata, skb);
+}
+
+/**
+ * ieee80211_mps_local_status_update - track status of local link-specific PMs
+ *
+ * @sdata: local mesh subif
+ *
+ * sets the non-peer power mode and triggers the driver PS (re-)configuration
+ */
+void ieee80211_mps_local_status_update(struct ieee80211_sub_if_data *sdata)
+{
+	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
+	struct sta_info *sta;
+	bool peering = false;
+	int light_sleep_cnt = 0;
+	int deep_sleep_cnt = 0;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(sta, &sdata->local->sta_list, list) {
+		if (sdata != sta->sdata)
+			continue;
+
+		switch (sta->plink_state) {
+		case NL80211_PLINK_OPN_SNT:
+		case NL80211_PLINK_OPN_RCVD:
+		case NL80211_PLINK_CNF_RCVD:
+			peering = true;
+			break;
+		case NL80211_PLINK_ESTAB:
+			if (sta->local_pm == NL80211_MESH_POWER_LIGHT_SLEEP)
+				light_sleep_cnt++;
+			else if (sta->local_pm == NL80211_MESH_POWER_DEEP_SLEEP)
+				deep_sleep_cnt++;
+			break;
+		default:
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	/*
+	 * Set non-peer mode to active during peering/scanning/authentication
+	 * (see IEEE802.11-2012 13.14.8.3). The non-peer mesh power mode is
+	 * deep sleep if the local STA is in light or deep sleep towards at
+	 * least one mesh peer (see 13.14.3.1). Otherwise, set it to the
+	 * user-configured default value.
+	 */
+	if (peering) {
+		mps_dbg(sdata, "setting non-peer PM to active for peering\n");
+		ifmsh->nonpeer_pm = NL80211_MESH_POWER_ACTIVE;
+	} else if (light_sleep_cnt || deep_sleep_cnt) {
+		mps_dbg(sdata, "setting non-peer PM to deep sleep\n");
+		ifmsh->nonpeer_pm = NL80211_MESH_POWER_DEEP_SLEEP;
+	} else {
+		mps_dbg(sdata, "setting non-peer PM to user value\n");
+		ifmsh->nonpeer_pm = ifmsh->mshcfg.power_mode;
+	}
+
+	ifmsh->ps_peers_light_sleep = light_sleep_cnt;
+	ifmsh->ps_peers_deep_sleep = deep_sleep_cnt;
+}
+
+/**
+ * ieee80211_mps_set_sta_local_pm - set local PM towards a mesh STA
+ *
+ * @sta: mesh STA
+ * @pm: the power mode to set
+ */
+void ieee80211_mps_set_sta_local_pm(struct sta_info *sta,
+				    enum nl80211_mesh_power_mode pm)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+
+	mps_dbg(sdata, "local STA operates in mode %d with %pM\n",
+		pm, sta->sta.addr);
+
+	sta->local_pm = pm;
+
+	/*
+	 * announce peer-specific power mode transition
+	 * (see IEEE802.11-2012 13.14.3.2 and 13.14.3.3)
+	 */
+	if (sta->plink_state == NL80211_PLINK_ESTAB)
+		mps_qos_null_tx(sta);
+
+	ieee80211_mps_local_status_update(sdata);
+}
+
+/**
+ * ieee80211_mps_set_frame_flags - set mesh PS flags in FC (and QoS Control)
+ *
+ * @sdata: local mesh subif
+ * @sta: mesh STA
+ * @hdr: 802.11 frame header
+ *
+ * see IEEE802.11-2012 8.2.4.1.7 and 8.2.4.5.11
+ *
+ * NOTE: sta must be given when an individually-addressed QoS frame header
+ * is handled, for group-addressed and management frames it is not used
+ */
+void ieee80211_mps_set_frame_flags(struct ieee80211_sub_if_data *sdata,
+				   struct sta_info *sta,
+				   struct ieee80211_hdr *hdr)
+{
+	enum nl80211_mesh_power_mode pm;
+	u8 *qc;
+
+	if (WARN_ON(is_unicast_ether_addr(hdr->addr1) &&
+		    ieee80211_is_data_qos(hdr->frame_control) &&
+		    !sta))
+		return;
+
+	if (is_unicast_ether_addr(hdr->addr1) &&
+	    ieee80211_is_data_qos(hdr->frame_control) &&
+	    sta->plink_state == NL80211_PLINK_ESTAB)
+		pm = sta->local_pm;
+	else
+		pm = sdata->u.mesh.nonpeer_pm;
+
+	if (pm == NL80211_MESH_POWER_ACTIVE)
+		hdr->frame_control &= cpu_to_le16(~IEEE80211_FCTL_PM);
+	else
+		hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PM);
+
+	if (!ieee80211_is_data_qos(hdr->frame_control))
+		return;
+
+	qc = ieee80211_get_qos_ctl(hdr);
+
+	if ((is_unicast_ether_addr(hdr->addr1) &&
+	     pm == NL80211_MESH_POWER_DEEP_SLEEP) ||
+	    (is_multicast_ether_addr(hdr->addr1) &&
+	     sdata->u.mesh.ps_peers_deep_sleep > 0))
+		qc[1] |= (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
+	else
+		qc[1] &= ~(IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8);
+}
+
+/**
+ * ieee80211_mps_sta_status_update - update buffering status of neighbor STA
+ *
+ * @sta: mesh STA
+ *
+ * called after change of peering status or non-peer/peer-specific power mode
+ */
+void ieee80211_mps_sta_status_update(struct sta_info *sta)
+{
+	enum nl80211_mesh_power_mode pm;
+	bool do_buffer;
+
+	/*
+	 * use peer-specific power mode if peering is established and the
+	 * peer's power mode is known
+	 */
+	if (sta->plink_state == NL80211_PLINK_ESTAB &&
+	    sta->peer_pm != NL80211_MESH_POWER_UNKNOWN)
+		pm = sta->peer_pm;
+	else
+		pm = sta->nonpeer_pm;
+
+	do_buffer = (pm != NL80211_MESH_POWER_ACTIVE);
+
+	/* Don't let the same PS state be set twice */
+	if (test_sta_flag(sta, WLAN_STA_PS_STA) == do_buffer)
+		return;
+
+	if (do_buffer) {
+		set_sta_flag(sta, WLAN_STA_PS_STA);
+		atomic_inc(&sta->sdata->u.mesh.ps.num_sta_ps);
+		mps_dbg(sta->sdata, "start PS buffering frames towards %pM\n",
+			sta->sta.addr);
+	} else {
+		ieee80211_sta_ps_deliver_wakeup(sta);
+	}
+
+	/* clear the MPSP flags for non-peers or active STA */
+	if (sta->plink_state != NL80211_PLINK_ESTAB) {
+		clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
+		clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
+	} else if (!do_buffer) {
+		clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
+	}
+}
+
+static void mps_set_sta_peer_pm(struct sta_info *sta,
+				struct ieee80211_hdr *hdr)
+{
+	enum nl80211_mesh_power_mode pm;
+	u8 *qc = ieee80211_get_qos_ctl(hdr);
+
+	/*
+	 * Test Power Management field of frame control (PW) and
+	 * mesh power save level subfield of QoS control field (PSL)
+	 *
+	 * | PM | PSL| Mesh PM |
+	 * +----+----+---------+
+	 * | 0  |Rsrv|  Active |
+	 * | 1  | 0  |  Light  |
+	 * | 1  | 1  |  Deep   |
+	 */
+	if (ieee80211_has_pm(hdr->frame_control)) {
+		if (qc[1] & (IEEE80211_QOS_CTL_MESH_PS_LEVEL >> 8))
+			pm = NL80211_MESH_POWER_DEEP_SLEEP;
+		else
+			pm = NL80211_MESH_POWER_LIGHT_SLEEP;
+	} else {
+		pm = NL80211_MESH_POWER_ACTIVE;
+	}
+
+	if (sta->peer_pm == pm)
+		return;
+
+	mps_dbg(sta->sdata, "STA %pM enters mode %d\n",
+		sta->sta.addr, pm);
+
+	sta->peer_pm = pm;
+
+	ieee80211_mps_sta_status_update(sta);
+}
+
+static void mps_set_sta_nonpeer_pm(struct sta_info *sta,
+				   struct ieee80211_hdr *hdr)
+{
+	enum nl80211_mesh_power_mode pm;
+
+	if (ieee80211_has_pm(hdr->frame_control))
+		pm = NL80211_MESH_POWER_DEEP_SLEEP;
+	else
+		pm = NL80211_MESH_POWER_ACTIVE;
+
+	if (sta->nonpeer_pm == pm)
+		return;
+
+	mps_dbg(sta->sdata, "STA %pM sets non-peer mode to %d\n",
+		sta->sta.addr, pm);
+
+	sta->nonpeer_pm = pm;
+
+	ieee80211_mps_sta_status_update(sta);
+}
+
+/**
+ * ieee80211_mps_rx_h_sta_process - frame receive handler for mesh powersave
+ *
+ * @sta: STA info that transmitted the frame
+ * @hdr: IEEE 802.11 (QoS) Header
+ */
+void ieee80211_mps_rx_h_sta_process(struct sta_info *sta,
+				    struct ieee80211_hdr *hdr)
+{
+	if (is_unicast_ether_addr(hdr->addr1) &&
+	    ieee80211_is_data_qos(hdr->frame_control)) {
+		/*
+		 * individually addressed QoS Data/Null frames contain
+		 * peer link-specific PS mode towards the local STA
+		 */
+		mps_set_sta_peer_pm(sta, hdr);
+
+		/* check for mesh Peer Service Period trigger frames */
+		ieee80211_mpsp_trigger_process(ieee80211_get_qos_ctl(hdr),
+					       sta, false, false);
+	} else {
+		/*
+		 * can only determine non-peer PS mode
+		 * (see IEEE802.11-2012 8.2.4.1.7)
+		 */
+		mps_set_sta_nonpeer_pm(sta, hdr);
+	}
+}
+
+
+/* mesh PS frame release */
+
+static void mpsp_trigger_send(struct sta_info *sta, bool rspi, bool eosp)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct sk_buff *skb;
+	struct ieee80211_hdr *nullfunc;
+	struct ieee80211_tx_info *info;
+	u8 *qc;
+
+	skb = mps_qos_null_get(sta);
+	if (!skb)
+		return;
+
+	nullfunc = (struct ieee80211_hdr *) skb->data;
+	if (!eosp)
+		nullfunc->frame_control |=
+				cpu_to_le16(IEEE80211_FCTL_MOREDATA);
+	/*
+	 * | RSPI | EOSP |  MPSP triggering   |
+	 * +------+------+--------------------+
+	 * |  0   |  0   | local STA is owner |
+	 * |  0   |  1   | no MPSP (MPSP end) |
+	 * |  1   |  0   | both STA are owner |
+	 * |  1   |  1   | peer STA is owner  | see IEEE802.11-2012 13.14.9.2
+	 */
+	qc = ieee80211_get_qos_ctl(nullfunc);
+	if (rspi)
+		qc[1] |= (IEEE80211_QOS_CTL_RSPI >> 8);
+	if (eosp)
+		qc[0] |= IEEE80211_QOS_CTL_EOSP;
+
+	info = IEEE80211_SKB_CB(skb);
+
+	info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER |
+		       IEEE80211_TX_CTL_REQ_TX_STATUS;
+
+	mps_dbg(sdata, "sending MPSP trigger%s%s to %pM\n",
+		rspi ? " RSPI" : "", eosp ? " EOSP" : "", sta->sta.addr);
+
+	ieee80211_tx_skb(sdata, skb);
+}
+
+/**
+ * mpsp_qos_null_append - append QoS Null frame to MPSP skb queue if needed
+ *
+ * To properly end a mesh MPSP the last transmitted frame has to set the EOSP
+ * flag in the QoS Control field. In case the current tailing frame is not a
+ * QoS Data frame, append a QoS Null to carry the flag.
+ */
+static void mpsp_qos_null_append(struct sta_info *sta,
+				 struct sk_buff_head *frames)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct sk_buff *new_skb, *skb = skb_peek_tail(frames);
+	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
+	struct ieee80211_tx_info *info;
+
+	if (ieee80211_is_data_qos(hdr->frame_control))
+		return;
+
+	new_skb = mps_qos_null_get(sta);
+	if (!new_skb)
+		return;
+
+	mps_dbg(sdata, "appending QoS Null in MPSP towards %pM\n",
+		sta->sta.addr);
+	/*
+	 * This frame has to be transmitted last. Assign lowest priority to
+	 * make sure it cannot pass other frames when releasing multiple ACs.
+	 */
+	new_skb->priority = 1;
+	skb_set_queue_mapping(new_skb, IEEE80211_AC_BK);
+	ieee80211_set_qos_hdr(sdata, new_skb);
+
+	info = IEEE80211_SKB_CB(new_skb);
+	info->control.vif = &sdata->vif;
+	info->flags |= IEEE80211_TX_INTFL_NEED_TXPROCESSING;
+
+	__skb_queue_tail(frames, new_skb);
+}
+
+/**
+ * mps_frame_deliver - transmit frames during mesh powersave
+ *
+ * @sta: STA info to transmit to
+ * @n_frames: number of frames to transmit. -1 for all
+ */
+static void mps_frame_deliver(struct sta_info *sta, int n_frames)
+{
+	struct ieee80211_sub_if_data *sdata = sta->sdata;
+	struct ieee80211_local *local = sdata->local;
+	int ac;
+	struct sk_buff_head frames;
+	struct sk_buff *skb;
+	bool more_data = false;
+
+	skb_queue_head_init(&frames);
+
+	/* collect frame(s) from buffers */
+	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++) {
+		while (n_frames != 0) {
+			skb = skb_dequeue(&sta->tx_filtered[ac]);
+			if (!skb) {
+				skb = skb_dequeue(
+					&sta->ps_tx_buf[ac]);
+				if (skb)
+					local->total_ps_buffered--;
+			}
+			if (!skb)
+				break;
+			n_frames--;
+			__skb_queue_tail(&frames, skb);
+		}
+
+		if (!skb_queue_empty(&sta->tx_filtered[ac]) ||
+		    !skb_queue_empty(&sta->ps_tx_buf[ac]))
+			more_data = true;
+	}
+
+	/* nothing to send? -> EOSP */
+	if (skb_queue_empty(&frames)) {
+		mpsp_trigger_send(sta, false, true);
+		return;
+	}
+
+	/* in a MPSP make sure the last skb is a QoS Data frame */
+	if (test_sta_flag(sta, WLAN_STA_MPSP_OWNER))
+		mpsp_qos_null_append(sta, &frames);
+
+	mps_dbg(sta->sdata, "sending %d frames to PS STA %pM\n",
+		skb_queue_len(&frames), sta->sta.addr);
+
+	/* prepare collected frames for transmission */
+	skb_queue_walk(&frames, skb) {
+		struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+		struct ieee80211_hdr *hdr = (void *) skb->data;
+
+		/*
+		 * Tell TX path to send this frame even though the
+		 * STA may still remain is PS mode after this frame
+		 * exchange.
+		 */
+		info->flags |= IEEE80211_TX_CTL_NO_PS_BUFFER;
+
+		if (more_data || !skb_queue_is_last(&frames, skb))
+			hdr->frame_control |=
+				cpu_to_le16(IEEE80211_FCTL_MOREDATA);
+		else
+			hdr->frame_control &=
+				cpu_to_le16(~IEEE80211_FCTL_MOREDATA);
+
+		if (skb_queue_is_last(&frames, skb) &&
+		    ieee80211_is_data_qos(hdr->frame_control)) {
+			u8 *qoshdr = ieee80211_get_qos_ctl(hdr);
+
+			/* MPSP trigger frame ends service period */
+			*qoshdr |= IEEE80211_QOS_CTL_EOSP;
+			info->flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
+		}
+	}
+
+	ieee80211_add_pending_skbs(local, &frames);
+	sta_info_recalc_tim(sta);
+}
+
+/**
+ * ieee80211_mpsp_trigger_process - track status of mesh Peer Service Periods
+ *
+ * @qc: QoS Control field
+ * @sta: peer to start a MPSP with
+ * @tx: frame was transmitted by the local STA
+ * @acked: frame has been transmitted successfully
+ *
+ * NOTE: active mode STA may only serve as MPSP owner
+ */
+void ieee80211_mpsp_trigger_process(u8 *qc, struct sta_info *sta,
+				    bool tx, bool acked)
+{
+	u8 rspi = qc[1] & (IEEE80211_QOS_CTL_RSPI >> 8);
+	u8 eosp = qc[0] & IEEE80211_QOS_CTL_EOSP;
+
+	if (tx) {
+		if (rspi && acked)
+			set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
+
+		if (eosp)
+			clear_sta_flag(sta, WLAN_STA_MPSP_OWNER);
+		else if (acked &&
+			 test_sta_flag(sta, WLAN_STA_PS_STA) &&
+			 !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
+			mps_frame_deliver(sta, -1);
+	} else {
+		if (eosp)
+			clear_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
+		else if (sta->local_pm != NL80211_MESH_POWER_ACTIVE)
+			set_sta_flag(sta, WLAN_STA_MPSP_RECIPIENT);
+
+		if (rspi && !test_and_set_sta_flag(sta, WLAN_STA_MPSP_OWNER))
+			mps_frame_deliver(sta, -1);
+	}
+}
+
+/**
+ * ieee80211_mps_frame_release - release buffered frames in response to beacon
+ *
+ * @sta: mesh STA
+ * @elems: beacon IEs
+ *
+ * For peers if we have individually-addressed frames buffered or the peer
+ * indicates buffered frames, send a corresponding MPSP trigger frame. Since
+ * we do not evaluate the awake window duration, QoS Nulls are used as MPSP
+ * trigger frames. If the neighbour STA is not a peer, only send single frames.
+ */
+void ieee80211_mps_frame_release(struct sta_info *sta,
+				 struct ieee802_11_elems *elems)
+{
+	int ac, buffer_local = 0;
+	bool has_buffered = false;
+
+	/* TIM map only for LLID <= IEEE80211_MAX_AID */
+	if (sta->plink_state == NL80211_PLINK_ESTAB)
+		has_buffered = ieee80211_check_tim(elems->tim, elems->tim_len,
+				le16_to_cpu(sta->llid) % IEEE80211_MAX_AID);
+
+	if (has_buffered)
+		mps_dbg(sta->sdata, "%pM indicates buffered frames\n",
+			sta->sta.addr);
+
+	/* only transmit to PS STA with announced, non-zero awake window */
+	if (test_sta_flag(sta, WLAN_STA_PS_STA) &&
+	    (!elems->awake_window || !le16_to_cpu(*elems->awake_window)))
+		return;
+
+	for (ac = 0; ac < IEEE80211_NUM_ACS; ac++)
+		buffer_local += skb_queue_len(&sta->ps_tx_buf[ac]) +
+				skb_queue_len(&sta->tx_filtered[ac]);
+
+	if (!has_buffered && !buffer_local)
+		return;
+
+	if (sta->plink_state == NL80211_PLINK_ESTAB)
+		mpsp_trigger_send(sta, has_buffered, !buffer_local);
+	else
+		mps_frame_deliver(sta, 1);
+}