rc80211_minstrel_ht.c 23.1 KB
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/*
 * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
 *
 * 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 <linux/netdevice.h>
#include <linux/types.h>
#include <linux/skbuff.h>
#include <linux/debugfs.h>
#include <linux/random.h>
#include <linux/ieee80211.h>
#include <net/mac80211.h>
#include "rate.h"
#include "rc80211_minstrel.h"
#include "rc80211_minstrel_ht.h"

#define AVG_PKT_SIZE	1200
#define SAMPLE_COLUMNS	10
#define EWMA_LEVEL		75

/* Number of bits for an average sized packet */
#define MCS_NBITS (AVG_PKT_SIZE << 3)

/* Number of symbols for a packet with (bps) bits per symbol */
#define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))

/* Transmission time for a packet containing (syms) symbols */
#define MCS_SYMBOL_TIME(sgi, syms)					\
	(sgi ?								\
	  ((syms) * 18 + 4) / 5 :	/* syms * 3.6 us */		\
	  (syms) << 2			/* syms * 4 us */		\
	)

/* Transmit duration for the raw data part of an average sized packet */
#define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))

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/*
 * Define group sort order: HT40 -> SGI -> #streams
 */
#define GROUP_IDX(_streams, _sgi, _ht40)	\
	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\
	MINSTREL_MAX_STREAMS * _sgi +		\
	_streams - 1

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/* MCS rate information for an MCS group */
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#define MCS_GROUP(_streams, _sgi, _ht40)				\
	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\
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	.streams = _streams,						\
	.flags =							\
		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
		(_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),		\
	.duration = {							\
		MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26),		\
		MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52),		\
		MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78),		\
		MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104),	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156),	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208),	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234),	\
		MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260)		\
	}								\
}

/*
 * To enable sufficiently targeted rate sampling, MCS rates are divided into
 * groups, based on the number of streams and flags (HT40, SGI) that they
 * use.
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 *
 * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
 * HT40 -> SGI -> #streams
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 */
const struct mcs_group minstrel_mcs_groups[] = {
	MCS_GROUP(1, 0, 0),
	MCS_GROUP(2, 0, 0),
#if MINSTREL_MAX_STREAMS >= 3
	MCS_GROUP(3, 0, 0),
#endif

	MCS_GROUP(1, 1, 0),
	MCS_GROUP(2, 1, 0),
#if MINSTREL_MAX_STREAMS >= 3
	MCS_GROUP(3, 1, 0),
#endif

	MCS_GROUP(1, 0, 1),
	MCS_GROUP(2, 0, 1),
#if MINSTREL_MAX_STREAMS >= 3
	MCS_GROUP(3, 0, 1),
#endif

	MCS_GROUP(1, 1, 1),
	MCS_GROUP(2, 1, 1),
#if MINSTREL_MAX_STREAMS >= 3
	MCS_GROUP(3, 1, 1),
#endif
};

static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];

/*
 * Perform EWMA (Exponentially Weighted Moving Average) calculation
 */
static int
minstrel_ewma(int old, int new, int weight)
{
	return (new * (100 - weight) + old * weight) / 100;
}

/*
 * Look up an MCS group index based on mac80211 rate information
 */
static int
minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
{
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	return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
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}

static inline struct minstrel_rate_stats *
minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
{
	return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
}


/*
 * Recalculate success probabilities and counters for a rate using EWMA
 */
static void
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minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
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{
	if (unlikely(mr->attempts > 0)) {
		mr->sample_skipped = 0;
		mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
		if (!mr->att_hist)
			mr->probability = mr->cur_prob;
		else
			mr->probability = minstrel_ewma(mr->probability,
				mr->cur_prob, EWMA_LEVEL);
		mr->att_hist += mr->attempts;
		mr->succ_hist += mr->success;
	} else {
		mr->sample_skipped++;
	}
	mr->last_success = mr->success;
	mr->last_attempts = mr->attempts;
	mr->success = 0;
	mr->attempts = 0;
}

/*
 * Calculate throughput based on the average A-MPDU length, taking into account
 * the expected number of retransmissions and their expected length
 */
static void
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minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
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{
	struct minstrel_rate_stats *mr;
	unsigned int usecs;

	mr = &mi->groups[group].rates[rate];

	if (mr->probability < MINSTREL_FRAC(1, 10)) {
		mr->cur_tp = 0;
		return;
	}

	usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
	usecs += minstrel_mcs_groups[group].duration[rate];
	mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
}

/*
 * Update rate statistics and select new primary rates
 *
 * Rules for rate selection:
 *  - max_prob_rate must use only one stream, as a tradeoff between delivery
 *    probability and throughput during strong fluctuations
 *  - as long as the max prob rate has a probability of more than 3/4, pick
 *    higher throughput rates, even if the probablity is a bit lower
 */
static void
minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
	struct minstrel_mcs_group_data *mg;
	struct minstrel_rate_stats *mr;
	int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
	int group, i, index;

	if (mi->ampdu_packets > 0) {
		mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
			MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
		mi->ampdu_len = 0;
		mi->ampdu_packets = 0;
	}

	mi->sample_slow = 0;
	mi->sample_count = 0;
	mi->max_tp_rate = 0;
	mi->max_tp_rate2 = 0;
	mi->max_prob_rate = 0;

	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
		cur_prob = 0;
		cur_prob_tp = 0;
		cur_tp = 0;
		cur_tp2 = 0;

		mg = &mi->groups[group];
		if (!mg->supported)
			continue;

		mg->max_tp_rate = 0;
		mg->max_tp_rate2 = 0;
		mg->max_prob_rate = 0;
		mi->sample_count++;

		for (i = 0; i < MCS_GROUP_RATES; i++) {
			if (!(mg->supported & BIT(i)))
				continue;

			mr = &mg->rates[i];
			mr->retry_updated = false;
			index = MCS_GROUP_RATES * group + i;
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			minstrel_calc_rate_ewma(mr);
			minstrel_ht_calc_tp(mi, group, i);
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			if (!mr->cur_tp)
				continue;

			/* ignore the lowest rate of each single-stream group */
			if (!i && minstrel_mcs_groups[group].streams == 1)
				continue;

			if ((mr->cur_tp > cur_prob_tp && mr->probability >
			     MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
				mg->max_prob_rate = index;
				cur_prob = mr->probability;
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				cur_prob_tp = mr->cur_tp;
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			}

			if (mr->cur_tp > cur_tp) {
				swap(index, mg->max_tp_rate);
				cur_tp = mr->cur_tp;
				mr = minstrel_get_ratestats(mi, index);
			}

			if (index >= mg->max_tp_rate)
				continue;

			if (mr->cur_tp > cur_tp2) {
				mg->max_tp_rate2 = index;
				cur_tp2 = mr->cur_tp;
			}
		}
	}

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	/* try to sample up to half of the available rates during each interval */
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	mi->sample_count *= 4;

	cur_prob = 0;
	cur_prob_tp = 0;
	cur_tp = 0;
	cur_tp2 = 0;
	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
		mg = &mi->groups[group];
		if (!mg->supported)
			continue;

		mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
		if (cur_prob_tp < mr->cur_tp &&
		    minstrel_mcs_groups[group].streams == 1) {
			mi->max_prob_rate = mg->max_prob_rate;
			cur_prob = mr->cur_prob;
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			cur_prob_tp = mr->cur_tp;
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		}

		mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
		if (cur_tp < mr->cur_tp) {
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			mi->max_tp_rate2 = mi->max_tp_rate;
			cur_tp2 = cur_tp;
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			mi->max_tp_rate = mg->max_tp_rate;
			cur_tp = mr->cur_tp;
		}

		mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
		if (cur_tp2 < mr->cur_tp) {
			mi->max_tp_rate2 = mg->max_tp_rate2;
			cur_tp2 = mr->cur_tp;
		}
	}

	mi->stats_update = jiffies;
}

static bool
minstrel_ht_txstat_valid(struct ieee80211_tx_rate *rate)
{
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	if (rate->idx < 0)
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		return false;

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	if (!rate->count)
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		return false;

	return !!(rate->flags & IEEE80211_TX_RC_MCS);
}

static void
minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
{
	struct minstrel_mcs_group_data *mg;

	for (;;) {
		mi->sample_group++;
		mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
		mg = &mi->groups[mi->sample_group];

		if (!mg->supported)
			continue;

		if (++mg->index >= MCS_GROUP_RATES) {
			mg->index = 0;
			if (++mg->column >= ARRAY_SIZE(sample_table))
				mg->column = 0;
		}
		break;
	}
}

static void
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minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
			bool primary)
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{
	int group, orig_group;

	orig_group = group = *idx / MCS_GROUP_RATES;
	while (group > 0) {
		group--;

		if (!mi->groups[group].supported)
			continue;

		if (minstrel_mcs_groups[group].streams >
		    minstrel_mcs_groups[orig_group].streams)
			continue;

		if (primary)
			*idx = mi->groups[group].max_tp_rate;
		else
			*idx = mi->groups[group].max_tp_rate2;
		break;
	}
}

static void
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minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
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{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
	u16 tid;

	if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
		return;

	if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
		return;

	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
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	if (likely(sta->ampdu_mlme.tid_tx[tid]))
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		return;

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	if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
		return;

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	ieee80211_start_tx_ba_session(pubsta, tid, 5000);
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}

static void
minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
                      struct ieee80211_sta *sta, void *priv_sta,
                      struct sk_buff *skb)
{
	struct minstrel_ht_sta_priv *msp = priv_sta;
	struct minstrel_ht_sta *mi = &msp->ht;
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
	struct ieee80211_tx_rate *ar = info->status.rates;
	struct minstrel_rate_stats *rate, *rate2;
	struct minstrel_priv *mp = priv;
	bool last = false;
	int group;
	int i = 0;

	if (!msp->is_ht)
		return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);

	/* This packet was aggregated but doesn't carry status info */
	if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
	    !(info->flags & IEEE80211_TX_STAT_AMPDU))
		return;

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	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
		info->status.ampdu_ack_len =
			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
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		info->status.ampdu_len = 1;
	}

	mi->ampdu_packets++;
	mi->ampdu_len += info->status.ampdu_len;

	if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
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		mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
		mi->sample_tries = 2;
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		mi->sample_count--;
	}

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	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
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		mi->sample_packets += info->status.ampdu_len;

	for (i = 0; !last; i++) {
		last = (i == IEEE80211_TX_MAX_RATES - 1) ||
		       !minstrel_ht_txstat_valid(&ar[i + 1]);

		if (!minstrel_ht_txstat_valid(&ar[i]))
			break;

		group = minstrel_ht_get_group_idx(&ar[i]);
		rate = &mi->groups[group].rates[ar[i].idx % 8];

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		if (last)
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			rate->success += info->status.ampdu_ack_len;

		rate->attempts += ar[i].count * info->status.ampdu_len;
	}

	/*
	 * check for sudden death of spatial multiplexing,
	 * downgrade to a lower number of streams if necessary.
	 */
	rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
	if (rate->attempts > 30 &&
	    MINSTREL_FRAC(rate->success, rate->attempts) <
	    MINSTREL_FRAC(20, 100))
		minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);

	rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
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	if (rate2->attempts > 30 &&
	    MINSTREL_FRAC(rate2->success, rate2->attempts) <
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	    MINSTREL_FRAC(20, 100))
		minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);

	if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
		minstrel_ht_update_stats(mp, mi);
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		if (!(info->flags & IEEE80211_TX_CTL_AMPDU))
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			minstrel_aggr_check(sta, skb);
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	}
}

static void
minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
                         int index)
{
	struct minstrel_rate_stats *mr;
	const struct mcs_group *group;
	unsigned int tx_time, tx_time_rtscts, tx_time_data;
	unsigned int cw = mp->cw_min;
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	unsigned int ctime = 0;
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	unsigned int t_slot = 9; /* FIXME */
	unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);

	mr = minstrel_get_ratestats(mi, index);
	if (mr->probability < MINSTREL_FRAC(1, 10)) {
		mr->retry_count = 1;
		mr->retry_count_rtscts = 1;
		return;
	}

	mr->retry_count = 2;
	mr->retry_count_rtscts = 2;
	mr->retry_updated = true;

	group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len;
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	/* Contention time for first 2 tries */
	ctime = (t_slot * cw) >> 1;
	cw = min((cw << 1) | 1, mp->cw_max);
	ctime += (t_slot * cw) >> 1;
	cw = min((cw << 1) | 1, mp->cw_max);

	/* Total TX time for data and Contention after first 2 tries */
	tx_time = ctime + 2 * (mi->overhead + tx_time_data);
	tx_time_rtscts = ctime + 2 * (mi->overhead_rtscts + tx_time_data);

	/* See how many more tries we can fit inside segment size */
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	do {
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		/* Contention time for this try */
		ctime = (t_slot * cw) >> 1;
		cw = min((cw << 1) | 1, mp->cw_max);

		/* Total TX time after this try */
		tx_time += ctime + mi->overhead + tx_time_data;
		tx_time_rtscts += ctime + mi->overhead_rtscts + tx_time_data;

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		if (tx_time_rtscts < mp->segment_size)
			mr->retry_count_rtscts++;
	} while ((tx_time < mp->segment_size) &&
	         (++mr->retry_count < mp->max_retry));
}


static void
minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
                     struct ieee80211_tx_rate *rate, int index,
                     bool sample, bool rtscts)
{
	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
	struct minstrel_rate_stats *mr;

	mr = minstrel_get_ratestats(mi, index);
	if (!mr->retry_updated)
		minstrel_calc_retransmit(mp, mi, index);

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	if (sample)
		rate->count = 1;
	else if (mr->probability < MINSTREL_FRAC(20, 100))
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		rate->count = 2;
	else if (rtscts)
		rate->count = mr->retry_count_rtscts;
	else
		rate->count = mr->retry_count;

	rate->flags = IEEE80211_TX_RC_MCS | group->flags;
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	if (rtscts)
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		rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
	rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
}

static inline int
minstrel_get_duration(int index)
{
	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
	return group->duration[index % MCS_GROUP_RATES];
}

static int
minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
	struct minstrel_rate_stats *mr;
	struct minstrel_mcs_group_data *mg;
	int sample_idx = 0;

	if (mi->sample_wait > 0) {
		mi->sample_wait--;
		return -1;
	}

	if (!mi->sample_tries)
		return -1;

	mi->sample_tries--;
	mg = &mi->groups[mi->sample_group];
	sample_idx = sample_table[mg->column][mg->index];
	mr = &mg->rates[sample_idx];
	sample_idx += mi->sample_group * MCS_GROUP_RATES;
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	minstrel_next_sample_idx(mi);
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	/*
	 * When not using MRR, do not sample if the probability is already
	 * higher than 95% to avoid wasting airtime
	 */
	if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
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		return -1;
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	/*
	 * Make sure that lower rates get sampled only occasionally,
	 * if the link is working perfectly.
	 */
	if (minstrel_get_duration(sample_idx) >
	    minstrel_get_duration(mi->max_tp_rate)) {
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		if (mr->sample_skipped < 20)
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			return -1;
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		if (mi->sample_slow++ > 2)
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			return -1;
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	}

	return sample_idx;
}

static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
                     struct ieee80211_tx_rate_control *txrc)
{
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
	struct ieee80211_tx_rate *ar = info->status.rates;
	struct minstrel_ht_sta_priv *msp = priv_sta;
	struct minstrel_ht_sta *mi = &msp->ht;
	struct minstrel_priv *mp = priv;
	int sample_idx;
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	bool sample = false;
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	if (rate_control_send_low(sta, priv_sta, txrc))
		return;

	if (!msp->is_ht)
		return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);

	info->flags |= mi->tx_flags;
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	/* Don't use EAPOL frames for sampling on non-mrr hw */
	if (mp->hw->max_rates == 1 &&
	    txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
		sample_idx = -1;
	else
		sample_idx = minstrel_get_sample_rate(mp, mi);
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#ifdef CONFIG_MAC80211_DEBUGFS
	/* use fixed index if set */
	if (mp->fixed_rate_idx != -1)
		sample_idx = mp->fixed_rate_idx;
#endif

626
	if (sample_idx >= 0) {
627
		sample = true;
628
		minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
629
			true, false);
630 631 632
		info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
	} else {
		minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
633
			false, false);
634 635
	}

636 637 638 639 640 641 642 643
	if (mp->hw->max_rates >= 3) {
		/*
		 * At least 3 tx rates supported, use
		 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
		 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
		 */
		if (sample_idx >= 0)
			minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
644
				false, false);
645 646
		else
			minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
647
				false, true);
648 649

		minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
650
				     false, !sample);
651 652 653 654 655 656 657 658 659 660

		ar[3].count = 0;
		ar[3].idx = -1;
	} else if (mp->hw->max_rates == 2) {
		/*
		 * Only 2 tx rates supported, use
		 * sample_rate -> max_prob_rate for sampling and
		 * max_tp_rate -> max_prob_rate by default.
		 */
		minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
661
				     false, !sample);
662 663 664 665 666 667 668 669

		ar[2].count = 0;
		ar[2].idx = -1;
	} else {
		/* Not using MRR, only use the first rate */
		ar[1].count = 0;
		ar[1].idx = -1;
	}
670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690

	mi->total_packets++;

	/* wraparound */
	if (mi->total_packets == ~0) {
		mi->total_packets = 0;
		mi->sample_packets = 0;
	}
}

static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
                        struct ieee80211_sta *sta, void *priv_sta,
			enum nl80211_channel_type oper_chan_type)
{
	struct minstrel_priv *mp = priv;
	struct minstrel_ht_sta_priv *msp = priv_sta;
	struct minstrel_ht_sta *mi = &msp->ht;
	struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
	struct ieee80211_local *local = hw_to_local(mp->hw);
	u16 sta_cap = sta->ht_cap.cap;
691
	int n_supported = 0;
692 693 694
	int ack_dur;
	int stbc;
	int i;
695
	unsigned int smps;
696 697

	/* fall back to the old minstrel for legacy stations */
698 699
	if (!sta->ht_cap.ht_supported)
		goto use_legacy;
700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734

	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
		MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);

	msp->is_ht = true;
	memset(mi, 0, sizeof(*mi));
	mi->stats_update = jiffies;

	ack_dur = ieee80211_frame_duration(local, 10, 60, 1, 1);
	mi->overhead = ieee80211_frame_duration(local, 0, 60, 1, 1) + ack_dur;
	mi->overhead_rtscts = mi->overhead + 2 * ack_dur;

	mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);

	/* When using MRR, sample more on the first attempt, without delay */
	if (mp->has_mrr) {
		mi->sample_count = 16;
		mi->sample_wait = 0;
	} else {
		mi->sample_count = 8;
		mi->sample_wait = 8;
	}
	mi->sample_tries = 4;

	stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
		IEEE80211_HT_CAP_RX_STBC_SHIFT;
	mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;

	if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
		mi->tx_flags |= IEEE80211_TX_CTL_LDPC;

	if (oper_chan_type != NL80211_CHAN_HT40MINUS &&
	    oper_chan_type != NL80211_CHAN_HT40PLUS)
		sta_cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;

735 736 737
	smps = (sta_cap & IEEE80211_HT_CAP_SM_PS) >>
		IEEE80211_HT_CAP_SM_PS_SHIFT;

738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754
	for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
		u16 req = 0;

		mi->groups[i].supported = 0;
		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
			if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
				req |= IEEE80211_HT_CAP_SGI_40;
			else
				req |= IEEE80211_HT_CAP_SGI_20;
		}

		if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
			req |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;

		if ((sta_cap & req) != req)
			continue;

755 756 757 758 759
		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
		if (smps == WLAN_HT_CAP_SM_PS_STATIC &&
		    minstrel_mcs_groups[i].streams > 1)
			continue;

760 761
		mi->groups[i].supported =
			mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
762 763 764

		if (mi->groups[i].supported)
			n_supported++;
765
	}
766 767 768 769 770 771 772 773 774 775 776 777

	if (!n_supported)
		goto use_legacy;

	return;

use_legacy:
	msp->is_ht = false;
	memset(&msp->legacy, 0, sizeof(msp->legacy));
	msp->legacy.r = msp->ratelist;
	msp->legacy.sample_table = msp->sample_table;
	return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827
}

static void
minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
                      struct ieee80211_sta *sta, void *priv_sta)
{
	struct minstrel_priv *mp = priv;

	minstrel_ht_update_caps(priv, sband, sta, priv_sta, mp->hw->conf.channel_type);
}

static void
minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
                        struct ieee80211_sta *sta, void *priv_sta,
                        u32 changed, enum nl80211_channel_type oper_chan_type)
{
	minstrel_ht_update_caps(priv, sband, sta, priv_sta, oper_chan_type);
}

static void *
minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
{
	struct ieee80211_supported_band *sband;
	struct minstrel_ht_sta_priv *msp;
	struct minstrel_priv *mp = priv;
	struct ieee80211_hw *hw = mp->hw;
	int max_rates = 0;
	int i;

	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
		sband = hw->wiphy->bands[i];
		if (sband && sband->n_bitrates > max_rates)
			max_rates = sband->n_bitrates;
	}

	msp = kzalloc(sizeof(struct minstrel_ht_sta), gfp);
	if (!msp)
		return NULL;

	msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
	if (!msp->ratelist)
		goto error;

	msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
	if (!msp->sample_table)
		goto error1;

	return msp;

error1:
828
	kfree(msp->ratelist);
829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904
error:
	kfree(msp);
	return NULL;
}

static void
minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
{
	struct minstrel_ht_sta_priv *msp = priv_sta;

	kfree(msp->sample_table);
	kfree(msp->ratelist);
	kfree(msp);
}

static void *
minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
{
	return mac80211_minstrel.alloc(hw, debugfsdir);
}

static void
minstrel_ht_free(void *priv)
{
	mac80211_minstrel.free(priv);
}

static struct rate_control_ops mac80211_minstrel_ht = {
	.name = "minstrel_ht",
	.tx_status = minstrel_ht_tx_status,
	.get_rate = minstrel_ht_get_rate,
	.rate_init = minstrel_ht_rate_init,
	.rate_update = minstrel_ht_rate_update,
	.alloc_sta = minstrel_ht_alloc_sta,
	.free_sta = minstrel_ht_free_sta,
	.alloc = minstrel_ht_alloc,
	.free = minstrel_ht_free,
#ifdef CONFIG_MAC80211_DEBUGFS
	.add_sta_debugfs = minstrel_ht_add_sta_debugfs,
	.remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
#endif
};


static void
init_sample_table(void)
{
	int col, i, new_idx;
	u8 rnd[MCS_GROUP_RATES];

	memset(sample_table, 0xff, sizeof(sample_table));
	for (col = 0; col < SAMPLE_COLUMNS; col++) {
		for (i = 0; i < MCS_GROUP_RATES; i++) {
			get_random_bytes(rnd, sizeof(rnd));
			new_idx = (i + rnd[i]) % MCS_GROUP_RATES;

			while (sample_table[col][new_idx] != 0xff)
				new_idx = (new_idx + 1) % MCS_GROUP_RATES;

			sample_table[col][new_idx] = i;
		}
	}
}

int __init
rc80211_minstrel_ht_init(void)
{
	init_sample_table();
	return ieee80211_rate_control_register(&mac80211_minstrel_ht);
}

void
rc80211_minstrel_ht_exit(void)
{
	ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
}