drivers/net/wireless/ath/ath9k/dynack.c - vendor/opensource/backports - Git at Google

 /*
  * Copyright (c) 2014, Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 #include "ath9k.h"
 #include "hw.h"
 #include "dynack.h"

 #define COMPUTE_TO		(5 * HZ)
 #define LATEACK_DELAY		(10 * HZ)
 #define LATEACK_TO		256
 #define MAX_DELAY		300
 #define EWMA_LEVEL		96
 #define EWMA_DIV		128

 /**
  * ath_dynack_ewma - EWMA (Exponentially Weighted Moving Average) calculation
  *
  */
 static inline u32 ath_dynack_ewma(u32 old, u32 new)
 {
 	return (new * (EWMA_DIV - EWMA_LEVEL) + old * EWMA_LEVEL) / EWMA_DIV;
 }

 /**
  * ath_dynack_get_sifs - get sifs time based on phy used
  * @ah: ath hw
  * @phy: phy used
  *
  */
 static inline u32 ath_dynack_get_sifs(struct ath_hw *ah, int phy)
 {
 	u32 sifs = CCK_SIFS_TIME;

 	if (phy == WLAN_RC_PHY_OFDM) {
 		if (IS_CHAN_QUARTER_RATE(ah->curchan))
 			sifs = OFDM_SIFS_TIME_QUARTER;
 		else if (IS_CHAN_HALF_RATE(ah->curchan))
 			sifs = OFDM_SIFS_TIME_HALF;
 		else
 			sifs = OFDM_SIFS_TIME;
 	}
 	return sifs;
 }

 /**
  * ath_dynack_bssidmask - filter out ACK frames based on BSSID mask
  * @ah: ath hw
  * @mac: receiver address
  */
 static inline bool ath_dynack_bssidmask(struct ath_hw *ah, const u8 *mac)
 {
 	int i;
 	struct ath_common *common = ath9k_hw_common(ah);

 	for (i = 0; i < ETH_ALEN; i++) {
 		if ((common->macaddr[i] & common->bssidmask[i]) !=
 		    (mac[i] & common->bssidmask[i]))
 			return false;
 	}

 	return true;
 }

 /**
  * ath_dynack_compute_ackto - compute ACK timeout as the maximum STA timeout
  * @ah: ath hw
  *
  * should be called while holding qlock
  */
 static void ath_dynack_compute_ackto(struct ath_hw *ah)
 {
 	struct ath_node *an;
 	u32 to = 0;
 	struct ath_dynack *da = &ah->dynack;
 	struct ath_common *common = ath9k_hw_common(ah);

 	list_for_each_entry(an, &da->nodes, list)
 		if (an->ackto > to)
 			to = an->ackto;

 	if (to && da->ackto != to) {
 		u32 slottime;

 		slottime = (to - 3) / 2;
 		da->ackto = to;
 		ath_dbg(common, DYNACK, "ACK timeout %u slottime %u\n",
 			da->ackto, slottime);
 		ath9k_hw_setslottime(ah, slottime);
 		ath9k_hw_set_ack_timeout(ah, da->ackto);
 		ath9k_hw_set_cts_timeout(ah, da->ackto);
 	}
 }

 /**
  * ath_dynack_compute_to - compute STA ACK timeout
  * @ah: ath hw
  *
  * should be called while holding qlock
  */
 static void ath_dynack_compute_to(struct ath_hw *ah)
 {
 	u32 ackto, ack_ts;
 	u8 *dst, *src;
 	struct ieee80211_sta *sta;
 	struct ath_node *an;
 	struct ts_info *st_ts;
 	struct ath_dynack *da = &ah->dynack;

 	rcu_read_lock();

 	while (da->st_rbf.h_rb != da->st_rbf.t_rb &&
 	       da->ack_rbf.h_rb != da->ack_rbf.t_rb) {
 		ack_ts = da->ack_rbf.tstamp[da->ack_rbf.h_rb];
 		st_ts = &da->st_rbf.ts[da->st_rbf.h_rb];
 		dst = da->st_rbf.addr[da->st_rbf.h_rb].h_dest;
 		src = da->st_rbf.addr[da->st_rbf.h_rb].h_src;

 		ath_dbg(ath9k_hw_common(ah), DYNACK,
 			"ack_ts %u st_ts %u st_dur %u [%u-%u]\n",
 			ack_ts, st_ts->tstamp, st_ts->dur,
 			da->ack_rbf.h_rb, da->st_rbf.h_rb);

 		if (ack_ts > st_ts->tstamp + st_ts->dur) {
 			ackto = ack_ts - st_ts->tstamp - st_ts->dur;

 			if (ackto < MAX_DELAY) {
 				sta = ieee80211_find_sta_by_ifaddr(ah->hw, dst,
 								   src);
 				if (sta) {
 					an = (struct ath_node *)sta->drv_priv;
 					an->ackto = ath_dynack_ewma(an->ackto,
 								    ackto);
 					ath_dbg(ath9k_hw_common(ah), DYNACK,
 						"%pM to %u\n", dst, an->ackto);
 					if (time_is_before_jiffies(da->lto)) {
 						ath_dynack_compute_ackto(ah);
 						da->lto = jiffies + COMPUTE_TO;
 					}
 				}
 				INCR(da->ack_rbf.h_rb, ATH_DYN_BUF);
 			}
 			INCR(da->st_rbf.h_rb, ATH_DYN_BUF);
 		} else {
 			INCR(da->ack_rbf.h_rb, ATH_DYN_BUF);
 		}
 	}

 	rcu_read_unlock();
 }

 /**
  * ath_dynack_sample_tx_ts - status timestamp sampling method
  * @ah: ath hw
  * @skb: socket buffer
  * @ts: tx status info
  *
  */
 void ath_dynack_sample_tx_ts(struct ath_hw *ah, struct sk_buff *skb,
 			     struct ath_tx_status *ts)
 {
 	u8 ridx;
 	struct ieee80211_hdr *hdr;
 	struct ath_dynack *da = &ah->dynack;
 	struct ath_common *common = ath9k_hw_common(ah);
 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

 	if ((info->flags & IEEE80211_TX_CTL_NO_ACK) || !da->enabled)
 		return;

 	spin_lock_bh(&da->qlock);

 	hdr = (struct ieee80211_hdr *)skb->data;

 	/* late ACK */
 	if (ts->ts_status & ATH9K_TXERR_XRETRY) {
 		if (ieee80211_is_assoc_req(hdr->frame_control) ||
 		    ieee80211_is_assoc_resp(hdr->frame_control)) {
 			ath_dbg(common, DYNACK, "late ack\n");
 			ath9k_hw_setslottime(ah, (LATEACK_TO - 3) / 2);
 			ath9k_hw_set_ack_timeout(ah, LATEACK_TO);
 			ath9k_hw_set_cts_timeout(ah, LATEACK_TO);
 			da->lto = jiffies + LATEACK_DELAY;
 		}

 		spin_unlock_bh(&da->qlock);
 		return;
 	}

 	ridx = ts->ts_rateindex;

 	da->st_rbf.ts[da->st_rbf.t_rb].tstamp = ts->ts_tstamp;
 	da->st_rbf.ts[da->st_rbf.t_rb].dur = ts->duration;
 	ether_addr_copy(da->st_rbf.addr[da->st_rbf.t_rb].h_dest, hdr->addr1);
 	ether_addr_copy(da->st_rbf.addr[da->st_rbf.t_rb].h_src, hdr->addr2);

 	if (!(info->status.rates[ridx].flags & IEEE80211_TX_RC_MCS)) {
 		u32 phy, sifs;
 		const struct ieee80211_rate *rate;
 		struct ieee80211_tx_rate *rates = info->status.rates;

 		rate = &common->sbands[info->band].bitrates[rates[ridx].idx];
 		if (info->band == IEEE80211_BAND_2GHZ &&
 		    !(rate->flags & IEEE80211_RATE_ERP_G))
 			phy = WLAN_RC_PHY_CCK;
 		else
 			phy = WLAN_RC_PHY_OFDM;

 		sifs = ath_dynack_get_sifs(ah, phy);
 		da->st_rbf.ts[da->st_rbf.t_rb].dur -= sifs;
 	}

 	ath_dbg(common, DYNACK, "{%pM} tx sample %u [dur %u][h %u-t %u]\n",
 		hdr->addr1, da->st_rbf.ts[da->st_rbf.t_rb].tstamp,
 		da->st_rbf.ts[da->st_rbf.t_rb].dur, da->st_rbf.h_rb,
 		(da->st_rbf.t_rb + 1) % ATH_DYN_BUF);

 	INCR(da->st_rbf.t_rb, ATH_DYN_BUF);
 	if (da->st_rbf.t_rb == da->st_rbf.h_rb)
 		INCR(da->st_rbf.h_rb, ATH_DYN_BUF);

 	ath_dynack_compute_to(ah);

 	spin_unlock_bh(&da->qlock);
 }
 EXPORT_SYMBOL(ath_dynack_sample_tx_ts);

 /**
  * ath_dynack_sample_ack_ts - ACK timestamp sampling method
  * @ah: ath hw
  * @skb: socket buffer
  * @ts: rx timestamp
  *
  */
 void ath_dynack_sample_ack_ts(struct ath_hw *ah, struct sk_buff *skb,
 			      u32 ts)
 {
 	struct ath_dynack *da = &ah->dynack;
 	struct ath_common *common = ath9k_hw_common(ah);
 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;

 	if (!ath_dynack_bssidmask(ah, hdr->addr1) || !da->enabled)
 		return;

 	spin_lock_bh(&da->qlock);
 	da->ack_rbf.tstamp[da->ack_rbf.t_rb] = ts;

 	ath_dbg(common, DYNACK, "rx sample %u [h %u-t %u]\n",
 		da->ack_rbf.tstamp[da->ack_rbf.t_rb],
 		da->ack_rbf.h_rb, (da->ack_rbf.t_rb + 1) % ATH_DYN_BUF);

 	INCR(da->ack_rbf.t_rb, ATH_DYN_BUF);
 	if (da->ack_rbf.t_rb == da->ack_rbf.h_rb)
 		INCR(da->ack_rbf.h_rb, ATH_DYN_BUF);

 	ath_dynack_compute_to(ah);

 	spin_unlock_bh(&da->qlock);
 }
 EXPORT_SYMBOL(ath_dynack_sample_ack_ts);

 /**
  * ath_dynack_node_init - init ath_node related info
  * @ah: ath hw
  * @an: ath node
  *
  */
 void ath_dynack_node_init(struct ath_hw *ah, struct ath_node *an)
 {
 	/* ackto = slottime + sifs + air delay */
 	u32 ackto = ATH9K_SLOT_TIME_9 + 16 + 64;
 	struct ath_dynack *da = &ah->dynack;

 	an->ackto = ackto;

 	spin_lock(&da->qlock);
 	list_add_tail(&an->list, &da->nodes);
 	spin_unlock(&da->qlock);
 }
 EXPORT_SYMBOL(ath_dynack_node_init);

 /**
  * ath_dynack_node_deinit - deinit ath_node related info
  * @ah: ath hw
  * @an: ath node
  *
  */
 void ath_dynack_node_deinit(struct ath_hw *ah, struct ath_node *an)
 {
 	struct ath_dynack *da = &ah->dynack;

 	spin_lock(&da->qlock);
 	list_del(&an->list);
 	spin_unlock(&da->qlock);
 }
 EXPORT_SYMBOL(ath_dynack_node_deinit);

 /**
  * ath_dynack_reset - reset dynack processing
  * @ah: ath hw
  *
  */
 void ath_dynack_reset(struct ath_hw *ah)
 {
 	/* ackto = slottime + sifs + air delay */
 	u32 ackto = ATH9K_SLOT_TIME_9 + 16 + 64;
 	struct ath_dynack *da = &ah->dynack;

 	da->lto = jiffies;
 	da->ackto = ackto;

 	da->st_rbf.t_rb = 0;
 	da->st_rbf.h_rb = 0;
 	da->ack_rbf.t_rb = 0;
 	da->ack_rbf.h_rb = 0;

 	/* init acktimeout */
 	ath9k_hw_setslottime(ah, (ackto - 3) / 2);
 	ath9k_hw_set_ack_timeout(ah, ackto);
 	ath9k_hw_set_cts_timeout(ah, ackto);
 }
 EXPORT_SYMBOL(ath_dynack_reset);

 /**
  * ath_dynack_init - init dynack data structure
  * @ah: ath hw
  *
  */
 void ath_dynack_init(struct ath_hw *ah)
 {
 	struct ath_dynack *da = &ah->dynack;

 	memset(da, 0, sizeof(struct ath_dynack));

 	spin_lock_init(&da->qlock);
 	INIT_LIST_HEAD(&da->nodes);

 	ah->hw->wiphy->features |= NL80211_FEATURE_ACKTO_ESTIMATION;
 }
	/*
	* Copyright (c) 2014, Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
	*
	* Permission to use, copy, modify, and/or distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	#include "ath9k.h"
	#include "hw.h"
	#include "dynack.h"

	#define COMPUTE_TO (5 * HZ)
	#define LATEACK_DELAY (10 * HZ)
	#define LATEACK_TO 256
	#define MAX_DELAY 300
	#define EWMA_LEVEL 96
	#define EWMA_DIV 128

	/**
	* ath_dynack_ewma - EWMA (Exponentially Weighted Moving Average) calculation
	*
	*/
	static inline u32 ath_dynack_ewma(u32 old, u32 new)
	{
	return (new * (EWMA_DIV - EWMA_LEVEL) + old * EWMA_LEVEL) / EWMA_DIV;
	}

	/**
	* ath_dynack_get_sifs - get sifs time based on phy used
	* @ah: ath hw
	* @phy: phy used
	*
	*/
	static inline u32 ath_dynack_get_sifs(struct ath_hw *ah, int phy)
	{
	u32 sifs = CCK_SIFS_TIME;

	if (phy == WLAN_RC_PHY_OFDM) {
	if (IS_CHAN_QUARTER_RATE(ah->curchan))
	sifs = OFDM_SIFS_TIME_QUARTER;
	else if (IS_CHAN_HALF_RATE(ah->curchan))
	sifs = OFDM_SIFS_TIME_HALF;
	else
	sifs = OFDM_SIFS_TIME;
	}
	return sifs;
	}

	/**
	* ath_dynack_bssidmask - filter out ACK frames based on BSSID mask
	* @ah: ath hw
	* @mac: receiver address
	*/
	static inline bool ath_dynack_bssidmask(struct ath_hw ah, const u8 mac)
	{
	int i;
	struct ath_common *common = ath9k_hw_common(ah);

	for (i = 0; i < ETH_ALEN; i++) {
	if ((common->macaddr[i] & common->bssidmask[i]) !=
	(mac[i] & common->bssidmask[i]))
	return false;
	}

	return true;
	}

	/**
	* ath_dynack_compute_ackto - compute ACK timeout as the maximum STA timeout
	* @ah: ath hw
	*
	* should be called while holding qlock
	*/
	static void ath_dynack_compute_ackto(struct ath_hw *ah)
	{
	struct ath_node *an;
	u32 to = 0;
	struct ath_dynack *da = &ah->dynack;
	struct ath_common *common = ath9k_hw_common(ah);

	list_for_each_entry(an, &da->nodes, list)
	if (an->ackto > to)
	to = an->ackto;

	if (to && da->ackto != to) {
	u32 slottime;

	slottime = (to - 3) / 2;
	da->ackto = to;
	ath_dbg(common, DYNACK, "ACK timeout %u slottime %u\n",
	da->ackto, slottime);
	ath9k_hw_setslottime(ah, slottime);
	ath9k_hw_set_ack_timeout(ah, da->ackto);
	ath9k_hw_set_cts_timeout(ah, da->ackto);
	}
	}

	/**
	* ath_dynack_compute_to - compute STA ACK timeout
	* @ah: ath hw
	*
	* should be called while holding qlock
	*/
	static void ath_dynack_compute_to(struct ath_hw *ah)
	{
	u32 ackto, ack_ts;
	u8 dst, src;
	struct ieee80211_sta *sta;
	struct ath_node *an;
	struct ts_info *st_ts;
	struct ath_dynack *da = &ah->dynack;

	rcu_read_lock();

	while (da->st_rbf.h_rb != da->st_rbf.t_rb &&
	da->ack_rbf.h_rb != da->ack_rbf.t_rb) {
	ack_ts = da->ack_rbf.tstamp[da->ack_rbf.h_rb];
	st_ts = &da->st_rbf.ts[da->st_rbf.h_rb];
	dst = da->st_rbf.addr[da->st_rbf.h_rb].h_dest;
	src = da->st_rbf.addr[da->st_rbf.h_rb].h_src;

	ath_dbg(ath9k_hw_common(ah), DYNACK,
	"ack_ts %u st_ts %u st_dur %u [%u-%u]\n",
	ack_ts, st_ts->tstamp, st_ts->dur,
	da->ack_rbf.h_rb, da->st_rbf.h_rb);

	if (ack_ts > st_ts->tstamp + st_ts->dur) {
	ackto = ack_ts - st_ts->tstamp - st_ts->dur;

	if (ackto < MAX_DELAY) {
	sta = ieee80211_find_sta_by_ifaddr(ah->hw, dst,
	src);
	if (sta) {
	an = (struct ath_node *)sta->drv_priv;
	an->ackto = ath_dynack_ewma(an->ackto,
	ackto);
	ath_dbg(ath9k_hw_common(ah), DYNACK,
	"%pM to %u\n", dst, an->ackto);
	if (time_is_before_jiffies(da->lto)) {
	ath_dynack_compute_ackto(ah);
	da->lto = jiffies + COMPUTE_TO;
	}
	}
	INCR(da->ack_rbf.h_rb, ATH_DYN_BUF);
	}
	INCR(da->st_rbf.h_rb, ATH_DYN_BUF);
	} else {
	INCR(da->ack_rbf.h_rb, ATH_DYN_BUF);
	}
	}

	rcu_read_unlock();
	}

	/**
	* ath_dynack_sample_tx_ts - status timestamp sampling method
	* @ah: ath hw
	* @skb: socket buffer
	* @ts: tx status info
	*
	*/
	void ath_dynack_sample_tx_ts(struct ath_hw ah, struct sk_buff skb,
	struct ath_tx_status *ts)
	{
	u8 ridx;
	struct ieee80211_hdr *hdr;
	struct ath_dynack *da = &ah->dynack;
	struct ath_common *common = ath9k_hw_common(ah);
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);

	if ((info->flags & IEEE80211_TX_CTL_NO_ACK) \|\| !da->enabled)
	return;

	spin_lock_bh(&da->qlock);

	hdr = (struct ieee80211_hdr *)skb->data;

	/* late ACK */
	if (ts->ts_status & ATH9K_TXERR_XRETRY) {
	if (ieee80211_is_assoc_req(hdr->frame_control) \|\|
	ieee80211_is_assoc_resp(hdr->frame_control)) {
	ath_dbg(common, DYNACK, "late ack\n");
	ath9k_hw_setslottime(ah, (LATEACK_TO - 3) / 2);
	ath9k_hw_set_ack_timeout(ah, LATEACK_TO);
	ath9k_hw_set_cts_timeout(ah, LATEACK_TO);
	da->lto = jiffies + LATEACK_DELAY;
	}

	spin_unlock_bh(&da->qlock);
	return;
	}

	ridx = ts->ts_rateindex;

	da->st_rbf.ts[da->st_rbf.t_rb].tstamp = ts->ts_tstamp;
	da->st_rbf.ts[da->st_rbf.t_rb].dur = ts->duration;
	ether_addr_copy(da->st_rbf.addr[da->st_rbf.t_rb].h_dest, hdr->addr1);
	ether_addr_copy(da->st_rbf.addr[da->st_rbf.t_rb].h_src, hdr->addr2);

	if (!(info->status.rates[ridx].flags & IEEE80211_TX_RC_MCS)) {
	u32 phy, sifs;
	const struct ieee80211_rate *rate;
	struct ieee80211_tx_rate *rates = info->status.rates;

	rate = &common->sbands[info->band].bitrates[rates[ridx].idx];
	if (info->band == IEEE80211_BAND_2GHZ &&
	!(rate->flags & IEEE80211_RATE_ERP_G))
	phy = WLAN_RC_PHY_CCK;
	else
	phy = WLAN_RC_PHY_OFDM;

	sifs = ath_dynack_get_sifs(ah, phy);
	da->st_rbf.ts[da->st_rbf.t_rb].dur -= sifs;
	}

	ath_dbg(common, DYNACK, "{%pM} tx sample %u [dur %u][h %u-t %u]\n",
	hdr->addr1, da->st_rbf.ts[da->st_rbf.t_rb].tstamp,
	da->st_rbf.ts[da->st_rbf.t_rb].dur, da->st_rbf.h_rb,
	(da->st_rbf.t_rb + 1) % ATH_DYN_BUF);

	INCR(da->st_rbf.t_rb, ATH_DYN_BUF);
	if (da->st_rbf.t_rb == da->st_rbf.h_rb)
	INCR(da->st_rbf.h_rb, ATH_DYN_BUF);

	ath_dynack_compute_to(ah);

	spin_unlock_bh(&da->qlock);
	}
	EXPORT_SYMBOL(ath_dynack_sample_tx_ts);

	/**
	* ath_dynack_sample_ack_ts - ACK timestamp sampling method
	* @ah: ath hw
	* @skb: socket buffer
	* @ts: rx timestamp
	*
	*/
	void ath_dynack_sample_ack_ts(struct ath_hw ah, struct sk_buff skb,
	u32 ts)
	{
	struct ath_dynack *da = &ah->dynack;
	struct ath_common *common = ath9k_hw_common(ah);
	struct ieee80211_hdr hdr = (struct ieee80211_hdr )skb->data;

	if (!ath_dynack_bssidmask(ah, hdr->addr1) \|\| !da->enabled)
	return;

	spin_lock_bh(&da->qlock);
	da->ack_rbf.tstamp[da->ack_rbf.t_rb] = ts;

	ath_dbg(common, DYNACK, "rx sample %u [h %u-t %u]\n",
	da->ack_rbf.tstamp[da->ack_rbf.t_rb],
	da->ack_rbf.h_rb, (da->ack_rbf.t_rb + 1) % ATH_DYN_BUF);

	INCR(da->ack_rbf.t_rb, ATH_DYN_BUF);
	if (da->ack_rbf.t_rb == da->ack_rbf.h_rb)
	INCR(da->ack_rbf.h_rb, ATH_DYN_BUF);

	ath_dynack_compute_to(ah);

	spin_unlock_bh(&da->qlock);
	}
	EXPORT_SYMBOL(ath_dynack_sample_ack_ts);

	/**
	* ath_dynack_node_init - init ath_node related info
	* @ah: ath hw
	* @an: ath node
	*
	*/
	void ath_dynack_node_init(struct ath_hw ah, struct ath_node an)
	{
	/* ackto = slottime + sifs + air delay */
	u32 ackto = ATH9K_SLOT_TIME_9 + 16 + 64;
	struct ath_dynack *da = &ah->dynack;

	an->ackto = ackto;

	spin_lock(&da->qlock);
	list_add_tail(&an->list, &da->nodes);
	spin_unlock(&da->qlock);
	}
	EXPORT_SYMBOL(ath_dynack_node_init);

	/**
	* ath_dynack_node_deinit - deinit ath_node related info
	* @ah: ath hw
	* @an: ath node
	*
	*/
	void ath_dynack_node_deinit(struct ath_hw ah, struct ath_node an)
	{
	struct ath_dynack *da = &ah->dynack;

	spin_lock(&da->qlock);
	list_del(&an->list);
	spin_unlock(&da->qlock);
	}
	EXPORT_SYMBOL(ath_dynack_node_deinit);

	/**
	* ath_dynack_reset - reset dynack processing
	* @ah: ath hw
	*
	*/
	void ath_dynack_reset(struct ath_hw *ah)
	{
	/* ackto = slottime + sifs + air delay */
	u32 ackto = ATH9K_SLOT_TIME_9 + 16 + 64;
	struct ath_dynack *da = &ah->dynack;

	da->lto = jiffies;
	da->ackto = ackto;

	da->st_rbf.t_rb = 0;
	da->st_rbf.h_rb = 0;
	da->ack_rbf.t_rb = 0;
	da->ack_rbf.h_rb = 0;

	/* init acktimeout */
	ath9k_hw_setslottime(ah, (ackto - 3) / 2);
	ath9k_hw_set_ack_timeout(ah, ackto);
	ath9k_hw_set_cts_timeout(ah, ackto);
	}
	EXPORT_SYMBOL(ath_dynack_reset);

	/**
	* ath_dynack_init - init dynack data structure
	* @ah: ath hw
	*
	*/
	void ath_dynack_init(struct ath_hw *ah)
	{
	struct ath_dynack *da = &ah->dynack;

	memset(da, 0, sizeof(struct ath_dynack));

	spin_lock_init(&da->qlock);
	INIT_LIST_HEAD(&da->nodes);

	ah->hw->wiphy->features \|= NL80211_FEATURE_ACKTO_ESTIMATION;
	}