rc80211_minstrel_ht.c 36.8 KB
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/*
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 * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
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 *
 * 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>
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#include <linux/moduleparam.h>
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#include <linux/ieee80211.h>
#include <net/mac80211.h>
#include "rate.h"
#include "rc80211_minstrel.h"
#include "rc80211_minstrel_ht.h"

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#define AVG_AMPDU_SIZE	16
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#define AVG_PKT_SIZE	1200

/* Number of bits for an average sized packet */
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#define MCS_NBITS ((AVG_PKT_SIZE * AVG_AMPDU_SIZE) << 3)
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/* Number of symbols for a packet with (bps) bits per symbol */
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#define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))
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/* Transmission time (nanoseconds) for a packet containing (syms) symbols */
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#define MCS_SYMBOL_TIME(sgi, syms)					\
	(sgi ?								\
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	  ((syms) * 18000 + 4000) / 5 :	/* syms * 3.6 us */		\
	  ((syms) * 1000) << 2		/* syms * 4 us */		\
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	)

/* Transmit duration for the raw data part of an average sized packet */
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#define MCS_DURATION(streams, sgi, bps) \
	(MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps))) / AVG_AMPDU_SIZE)
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#define BW_20			0
#define BW_40			1
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#define BW_80			2
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/*
 * Define group sort order: HT40 -> SGI -> #streams
 */
#define GROUP_IDX(_streams, _sgi, _ht40)	\
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	MINSTREL_HT_GROUP_0 +			\
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	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\
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	MINSTREL_MAX_STREAMS * _sgi +	\
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	_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 =							\
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		IEEE80211_TX_RC_MCS |					\
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		(_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)		\
	}								\
}

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#define VHT_GROUP_IDX(_streams, _sgi, _bw)				\
	(MINSTREL_VHT_GROUP_0 +						\
	 MINSTREL_MAX_STREAMS * 2 * (_bw) +				\
	 MINSTREL_MAX_STREAMS * (_sgi) +				\
	 (_streams) - 1)

#define BW2VBPS(_bw, r3, r2, r1)					\
	(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)

#define VHT_GROUP(_streams, _sgi, _bw)					\
	[VHT_GROUP_IDX(_streams, _sgi, _bw)] = {			\
	.streams = _streams,						\
	.flags =							\
		IEEE80211_TX_RC_VHT_MCS |				\
		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
		(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH :		\
		 _bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),	\
	.duration = {							\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  117,  54,  26)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  234, 108,  52)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  351, 162,  78)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  468, 216, 104)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  702, 324, 156)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw,  936, 432, 208)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1053, 486, 234)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1170, 540, 260)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1404, 648, 312)),		\
		MCS_DURATION(_streams, _sgi,				\
			     BW2VBPS(_bw, 1560, 720, 346))		\
	}								\
}

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#define CCK_DURATION(_bitrate, _short, _len)		\
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	(1000 * (10 /* SIFS */ +			\
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	 (_short ? 72 + 24 : 144 + 48) +		\
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	 (8 * (_len + 4) * 10) / (_bitrate)))
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#define CCK_ACK_DURATION(_bitrate, _short)			\
	(CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) +	\
	 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))

#define CCK_DURATION_LIST(_short)			\
	CCK_ACK_DURATION(10, _short),			\
	CCK_ACK_DURATION(20, _short),			\
	CCK_ACK_DURATION(55, _short),			\
	CCK_ACK_DURATION(110, _short)

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#define CCK_GROUP					\
	[MINSTREL_CCK_GROUP] = {			\
		.streams = 0,				\
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		.flags = 0,				\
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		.duration = {				\
			CCK_DURATION_LIST(false),	\
			CCK_DURATION_LIST(true)		\
		}					\
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	}

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#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
static bool minstrel_vht_only = true;
module_param(minstrel_vht_only, bool, 0644);
MODULE_PARM_DESC(minstrel_vht_only,
		 "Use only VHT rates when VHT is supported by sta.");
#endif

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/*
 * 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:
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 * BW -> SGI -> #streams
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 */
const struct mcs_group minstrel_mcs_groups[] = {
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	MCS_GROUP(1, 0, BW_20),
	MCS_GROUP(2, 0, BW_20),
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#if MINSTREL_MAX_STREAMS >= 3
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	MCS_GROUP(3, 0, BW_20),
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#endif

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	MCS_GROUP(1, 1, BW_20),
	MCS_GROUP(2, 1, BW_20),
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#if MINSTREL_MAX_STREAMS >= 3
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	MCS_GROUP(3, 1, BW_20),
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#endif

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	MCS_GROUP(1, 0, BW_40),
	MCS_GROUP(2, 0, BW_40),
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#if MINSTREL_MAX_STREAMS >= 3
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	MCS_GROUP(3, 0, BW_40),
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#endif

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	MCS_GROUP(1, 1, BW_40),
	MCS_GROUP(2, 1, BW_40),
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#if MINSTREL_MAX_STREAMS >= 3
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	MCS_GROUP(3, 1, BW_40),
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#endif
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	CCK_GROUP,

#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
	VHT_GROUP(1, 0, BW_20),
	VHT_GROUP(2, 0, BW_20),
#if MINSTREL_MAX_STREAMS >= 3
	VHT_GROUP(3, 0, BW_20),
#endif

	VHT_GROUP(1, 1, BW_20),
	VHT_GROUP(2, 1, BW_20),
#if MINSTREL_MAX_STREAMS >= 3
	VHT_GROUP(3, 1, BW_20),
#endif
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	VHT_GROUP(1, 0, BW_40),
	VHT_GROUP(2, 0, BW_40),
#if MINSTREL_MAX_STREAMS >= 3
	VHT_GROUP(3, 0, BW_40),
#endif

	VHT_GROUP(1, 1, BW_40),
	VHT_GROUP(2, 1, BW_40),
#if MINSTREL_MAX_STREAMS >= 3
	VHT_GROUP(3, 1, BW_40),
#endif

	VHT_GROUP(1, 0, BW_80),
	VHT_GROUP(2, 0, BW_80),
#if MINSTREL_MAX_STREAMS >= 3
	VHT_GROUP(3, 0, BW_80),
#endif

	VHT_GROUP(1, 1, BW_80),
	VHT_GROUP(2, 1, BW_80),
#if MINSTREL_MAX_STREAMS >= 3
	VHT_GROUP(3, 1, BW_80),
#endif
#endif
};
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static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
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static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);

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/*
 * Some VHT MCSes are invalid (when Ndbps / Nes is not an integer)
 * e.g for MCS9@20MHzx1Nss: Ndbps=8x52*(5/6) Nes=1
 *
 * Returns the valid mcs map for struct minstrel_mcs_group_data.supported
 */
static u16
minstrel_get_valid_vht_rates(int bw, int nss, __le16 mcs_map)
{
	u16 mask = 0;

	if (bw == BW_20) {
		if (nss != 3 && nss != 6)
			mask = BIT(9);
	} else if (bw == BW_80) {
		if (nss == 3 || nss == 7)
			mask = BIT(6);
		else if (nss == 6)
			mask = BIT(9);
	} else {
		WARN_ON(bw != BW_40);
	}

	switch ((le16_to_cpu(mcs_map) >> (2 * (nss - 1))) & 3) {
	case IEEE80211_VHT_MCS_SUPPORT_0_7:
		mask |= 0x300;
		break;
	case IEEE80211_VHT_MCS_SUPPORT_0_8:
		mask |= 0x200;
		break;
	case IEEE80211_VHT_MCS_SUPPORT_0_9:
		break;
	default:
		mask = 0x3ff;
	}

	return 0x3ff & ~mask;
}

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/*
 * 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 / 8) + 1,
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			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
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}

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static int
minstrel_vht_get_group_idx(struct ieee80211_tx_rate *rate)
{
	return VHT_GROUP_IDX(ieee80211_rate_get_vht_nss(rate),
			     !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
			     !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) +
			     2*!!(rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH));
}

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static struct minstrel_rate_stats *
minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
		      struct ieee80211_tx_rate *rate)
{
	int group, idx;

	if (rate->flags & IEEE80211_TX_RC_MCS) {
		group = minstrel_ht_get_group_idx(rate);
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		idx = rate->idx % 8;
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	} else if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
		group = minstrel_vht_get_group_idx(rate);
		idx = ieee80211_rate_get_vht_mcs(rate);
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	} else {
		group = MINSTREL_CCK_GROUP;

		for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
			if (rate->idx == mp->cck_rates[idx])
				break;

		/* short preamble */
		if (!(mi->groups[group].supported & BIT(idx)))
			idx += 4;
	}
	return &mi->groups[group].rates[idx];
}

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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;
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	unsigned int nsecs = 0;
	unsigned int tp;
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	unsigned int prob;
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	mr = &mi->groups[group].rates[rate];
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	prob = mr->probability;
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	if (prob < MINSTREL_FRAC(1, 10)) {
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		mr->cur_tp = 0;
		return;
	}

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	/*
	 * For the throughput calculation, limit the probability value to 90% to
	 * account for collision related packet error rate fluctuation
	 */
	if (prob > MINSTREL_FRAC(9, 10))
		prob = MINSTREL_FRAC(9, 10);

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	if (group != MINSTREL_CCK_GROUP)
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		nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
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	nsecs += minstrel_mcs_groups[group].duration[rate];

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	/* prob is scaled - see MINSTREL_FRAC above */
	tp = 1000000 * ((prob * 1000) / nsecs);
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	mr->cur_tp = MINSTREL_TRUNC(tp);
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}

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/*
 * Find & sort topmost throughput rates
 *
 * If multiple rates provide equal throughput the sorting is based on their
 * current success probability. Higher success probability is preferred among
 * MCS groups, CCK rates do not provide aggregation and are therefore at last.
 */
static void
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minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
			       u16 *tp_list)
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{
	int cur_group, cur_idx, cur_thr, cur_prob;
	int tmp_group, tmp_idx, tmp_thr, tmp_prob;
	int j = MAX_THR_RATES;

	cur_group = index / MCS_GROUP_RATES;
	cur_idx = index  % MCS_GROUP_RATES;
	cur_thr = mi->groups[cur_group].rates[cur_idx].cur_tp;
	cur_prob = mi->groups[cur_group].rates[cur_idx].probability;

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	do {
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		tmp_group = tp_list[j - 1] / MCS_GROUP_RATES;
		tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES;
		tmp_thr = mi->groups[tmp_group].rates[tmp_idx].cur_tp;
		tmp_prob = mi->groups[tmp_group].rates[tmp_idx].probability;
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		if (cur_thr < tmp_thr ||
		    (cur_thr == tmp_thr && cur_prob <= tmp_prob))
			break;
		j--;
	} while (j > 0);
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	if (j < MAX_THR_RATES - 1) {
		memmove(&tp_list[j + 1], &tp_list[j], (sizeof(*tp_list) *
		       (MAX_THR_RATES - (j + 1))));
	}
	if (j < MAX_THR_RATES)
		tp_list[j] = index;
}

/*
 * Find and set the topmost probability rate per sta and per group
 */
static void
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minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 index)
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{
	struct minstrel_mcs_group_data *mg;
	struct minstrel_rate_stats *mr;
	int tmp_group, tmp_idx, tmp_tp, tmp_prob, max_tp_group;

	mg = &mi->groups[index / MCS_GROUP_RATES];
	mr = &mg->rates[index % MCS_GROUP_RATES];

	tmp_group = mi->max_prob_rate / MCS_GROUP_RATES;
	tmp_idx = mi->max_prob_rate % MCS_GROUP_RATES;
	tmp_tp = mi->groups[tmp_group].rates[tmp_idx].cur_tp;
	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].probability;

	/* if max_tp_rate[0] is from MCS_GROUP max_prob_rate get selected from
	 * MCS_GROUP as well as CCK_GROUP rates do not allow aggregation */
	max_tp_group = mi->max_tp_rate[0] / MCS_GROUP_RATES;
	if((index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) &&
	    (max_tp_group != MINSTREL_CCK_GROUP))
		return;

	if (mr->probability > MINSTREL_FRAC(75, 100)) {
		if (mr->cur_tp > tmp_tp)
			mi->max_prob_rate = index;
		if (mr->cur_tp > mg->rates[mg->max_group_prob_rate].cur_tp)
			mg->max_group_prob_rate = index;
	} else {
		if (mr->probability > tmp_prob)
			mi->max_prob_rate = index;
		if (mr->probability > mg->rates[mg->max_group_prob_rate].probability)
			mg->max_group_prob_rate = index;
	}
}


/*
 * Assign new rate set per sta and use CCK rates only if the fastest
 * rate (max_tp_rate[0]) is from CCK group. This prohibits such sorted
 * rate sets where MCS and CCK rates are mixed, because CCK rates can
 * not use aggregation.
 */
static void
minstrel_ht_assign_best_tp_rates(struct minstrel_ht_sta *mi,
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				 u16 tmp_mcs_tp_rate[MAX_THR_RATES],
				 u16 tmp_cck_tp_rate[MAX_THR_RATES])
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{
	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp;
	int i;

	tmp_group = tmp_cck_tp_rate[0] / MCS_GROUP_RATES;
	tmp_idx = tmp_cck_tp_rate[0] % MCS_GROUP_RATES;
	tmp_cck_tp = mi->groups[tmp_group].rates[tmp_idx].cur_tp;

	tmp_group = tmp_mcs_tp_rate[0] / MCS_GROUP_RATES;
	tmp_idx = tmp_mcs_tp_rate[0] % MCS_GROUP_RATES;
	tmp_mcs_tp = mi->groups[tmp_group].rates[tmp_idx].cur_tp;

	if (tmp_cck_tp > tmp_mcs_tp) {
		for(i = 0; i < MAX_THR_RATES; i++) {
			minstrel_ht_sort_best_tp_rates(mi, tmp_cck_tp_rate[i],
						       tmp_mcs_tp_rate);
		}
	}

}

/*
 * Try to increase robustness of max_prob rate by decrease number of
 * streams if possible.
 */
static inline void
minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
{
	struct minstrel_mcs_group_data *mg;
	struct minstrel_rate_stats *mr;
	int tmp_max_streams, group;
	int tmp_tp = 0;

	tmp_max_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
			  MCS_GROUP_RATES].streams;
	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
		mg = &mi->groups[group];
		if (!mg->supported || group == MINSTREL_CCK_GROUP)
			continue;
		mr = minstrel_get_ratestats(mi, mg->max_group_prob_rate);
		if (tmp_tp < mr->cur_tp &&
		   (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
				mi->max_prob_rate = mg->max_group_prob_rate;
				tmp_tp = mr->cur_tp;
		}
	}
}

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/*
 * 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
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 *  - as long as the max prob rate has a probability of more than 75%, pick
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 *    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;
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	int group, i, j;
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	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
	u16 tmp_cck_tp_rate[MAX_THR_RATES], index;
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	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;

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	/* Initialize global rate indexes */
	for(j = 0; j < MAX_THR_RATES; j++){
		tmp_mcs_tp_rate[j] = 0;
		tmp_cck_tp_rate[j] = 0;
	}
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	/* Find best rate sets within all MCS groups*/
	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
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		mg = &mi->groups[group];
		if (!mg->supported)
			continue;

		mi->sample_count++;

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		/* (re)Initialize group rate indexes */
		for(j = 0; j < MAX_THR_RATES; j++)
			tmp_group_tp_rate[j] = group;

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

566 567
			index = MCS_GROUP_RATES * group + i;

568 569
			mr = &mg->rates[i];
			mr->retry_updated = false;
570 571
			minstrel_calc_rate_ewma(mr);
			minstrel_ht_calc_tp(mi, group, i);
572 573 574 575

			if (!mr->cur_tp)
				continue;

576 577 578 579 580 581 582
			/* Find max throughput rate set */
			if (group != MINSTREL_CCK_GROUP) {
				minstrel_ht_sort_best_tp_rates(mi, index,
							       tmp_mcs_tp_rate);
			} else if (group == MINSTREL_CCK_GROUP) {
				minstrel_ht_sort_best_tp_rates(mi, index,
							       tmp_cck_tp_rate);
583 584
			}

585 586 587
			/* Find max throughput rate set within a group */
			minstrel_ht_sort_best_tp_rates(mi, index,
						       tmp_group_tp_rate);
588

589 590
			/* Find max probability rate per group and global */
			minstrel_ht_set_best_prob_rate(mi, index);
591 592
		}

593 594
		memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
		       sizeof(mg->max_group_tp_rate));
595 596
	}

597 598 599
	/* Assign new rate set per sta */
	minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate, tmp_cck_tp_rate);
	memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));
600

601 602 603 604 605
	/* Try to increase robustness of max_prob_rate*/
	minstrel_ht_prob_rate_reduce_streams(mi);

	/* try to sample all available rates during each interval */
	mi->sample_count *= 8;
606

607 608 609
#ifdef CONFIG_MAC80211_DEBUGFS
	/* use fixed index if set */
	if (mp->fixed_rate_idx != -1) {
610 611
		for (i = 0; i < 4; i++)
			mi->max_tp_rate[i] = mp->fixed_rate_idx;
612 613 614
		mi->max_prob_rate = mp->fixed_rate_idx;
	}
#endif
615

616
	/* Reset update timer */
617 618 619 620
	mi->stats_update = jiffies;
}

static bool
621
minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
622
{
623
	if (rate->idx < 0)
624 625
		return false;

626
	if (!rate->count)
627 628
		return false;

629 630
	if (rate->flags & IEEE80211_TX_RC_MCS ||
	    rate->flags & IEEE80211_TX_RC_VHT_MCS)
631 632 633 634 635 636
		return true;

	return rate->idx == mp->cck_rates[0] ||
	       rate->idx == mp->cck_rates[1] ||
	       rate->idx == mp->cck_rates[2] ||
	       rate->idx == mp->cck_rates[3];
637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661
}

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
662
minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
663 664 665 666 667 668 669 670 671 672 673 674 675 676 677
{
	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)
678
			*idx = mi->groups[group].max_group_tp_rate[0];
679
		else
680
			*idx = mi->groups[group].max_group_tp_rate[1];
681 682 683 684 685
		break;
	}
}

static void
686
minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
687 688 689 690 691
{
	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
	u16 tid;

692 693 694
	if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
		return;

695 696 697
	if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
		return;

698
	if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
699 700 701
		return;

	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
702
	if (likely(sta->ampdu_mlme.tid_tx[tid]))
703 704
		return;

705
	ieee80211_start_tx_ba_session(pubsta, tid, 5000);
706 707 708 709 710
}

static void
minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
                      struct ieee80211_sta *sta, void *priv_sta,
711
                      struct ieee80211_tx_info *info)
712 713 714 715 716 717
{
	struct minstrel_ht_sta_priv *msp = priv_sta;
	struct minstrel_ht_sta *mi = &msp->ht;
	struct ieee80211_tx_rate *ar = info->status.rates;
	struct minstrel_rate_stats *rate, *rate2;
	struct minstrel_priv *mp = priv;
718
	bool last, update = false;
719
	int i;
720 721

	if (!msp->is_ht)
722 723
		return mac80211_minstrel.tx_status_noskb(priv, sband, sta,
							 &msp->legacy, info);
724 725 726 727 728 729

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

730 731 732
	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
		info->status.ampdu_ack_len =
			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
733 734 735 736 737 738 739
		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) {
740
		mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
741
		mi->sample_tries = 1;
742 743 744
		mi->sample_count--;
	}

745
	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
746 747
		mi->sample_packets += info->status.ampdu_len;

748
	last = !minstrel_ht_txstat_valid(mp, &ar[0]);
749 750
	for (i = 0; !last; i++) {
		last = (i == IEEE80211_TX_MAX_RATES - 1) ||
751
		       !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
752

753
		rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
754

755
		if (last)
756 757 758 759 760 761 762 763 764
			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.
	 */
765
	rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
766 767
	if (rate->attempts > 30 &&
	    MINSTREL_FRAC(rate->success, rate->attempts) <
768
	    MINSTREL_FRAC(20, 100)) {
769
		minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
770 771
		update = true;
	}
772

773
	rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
774 775
	if (rate2->attempts > 30 &&
	    MINSTREL_FRAC(rate2->success, rate2->attempts) <
776
	    MINSTREL_FRAC(20, 100)) {
777
		minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
778 779
		update = true;
	}
780 781

	if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
782
		update = true;
783 784
		minstrel_ht_update_stats(mp, mi);
	}
785 786 787

	if (update)
		minstrel_ht_update_rates(mp, mi);
788 789 790 791 792 793 794 795 796 797
}

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;
798
	unsigned int ctime = 0;
799 800
	unsigned int t_slot = 9; /* FIXME */
	unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
801
	unsigned int overhead = 0, overhead_rtscts = 0;
802 803 804 805 806 807 808 809 810 811 812 813 814

	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];
815
	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
816 817 818 819 820 821 822

	/* 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);

823 824 825 826 827
	if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
		overhead = mi->overhead;
		overhead_rtscts = mi->overhead_rtscts;
	}

828
	/* Total TX time for data and Contention after first 2 tries */
829 830
	tx_time = ctime + 2 * (overhead + tx_time_data);
	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
831 832

	/* See how many more tries we can fit inside segment size */
833
	do {
834 835 836 837 838
		/* Contention time for this try */
		ctime = (t_slot * cw) >> 1;
		cw = min((cw << 1) | 1, mp->cw_max);

		/* Total TX time after this try */
839 840
		tx_time += ctime + overhead + tx_time_data;
		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
841

842 843 844 845 846 847 848 849 850
		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,
851
                     struct ieee80211_sta_rates *ratetbl, int offset, int index)
852 853 854
{
	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
	struct minstrel_rate_stats *mr;
855
	u8 idx;
856
	u16 flags = group->flags;
857 858 859 860 861

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

862 863 864 865 866 867 868 869 870
	if (mr->probability < MINSTREL_FRAC(20, 100) || !mr->retry_count) {
		ratetbl->rate[offset].count = 2;
		ratetbl->rate[offset].count_rts = 2;
		ratetbl->rate[offset].count_cts = 2;
	} else {
		ratetbl->rate[offset].count = mr->retry_count;
		ratetbl->rate[offset].count_cts = mr->retry_count;
		ratetbl->rate[offset].count_rts = mr->retry_count_rtscts;
	}
871

872
	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP)
873
		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
874 875 876
	else if (flags & IEEE80211_TX_RC_VHT_MCS)
		idx = ((group->streams - 1) << 4) |
		      ((index % MCS_GROUP_RATES) & 0xF);
877
	else
878
		idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8;
879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896

	if (offset > 0) {
		ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
		flags |= IEEE80211_TX_RC_USE_RTS_CTS;
	}

	ratetbl->rate[offset].idx = idx;
	ratetbl->rate[offset].flags = flags;
}

static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
{
	struct ieee80211_sta_rates *rates;
	int i = 0;

	rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
	if (!rates)
897
		return;
898

899 900
	/* Start with max_tp_rate[0] */
	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);
901 902

	if (mp->hw->max_rates >= 3) {
903 904
		/* At least 3 tx rates supported, use max_tp_rate[1] next */
		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[1]);
905 906 907 908 909 910
	}

	if (mp->hw->max_rates >= 2) {
		/*
		 * At least 2 tx rates supported, use max_prob_rate next */
		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
911 912
	}

913 914
	rates->rate[i].idx = -1;
	rate_control_set_rates(mp->hw, mi->sta, rates);
915 916 917 918 919 920 921 922 923 924 925 926 927 928
}

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;
929
	unsigned int sample_dur, sample_group, cur_max_tp_streams;
930 931 932 933 934 935 936 937 938 939
	int sample_idx = 0;

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

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

940 941
	sample_group = mi->sample_group;
	mg = &mi->groups[sample_group];
942
	sample_idx = sample_table[mg->column][mg->index];
943 944 945 946 947
	minstrel_next_sample_idx(mi);

	if (!(mg->supported & BIT(sample_idx)))
		return -1;

948
	mr = &mg->rates[sample_idx];
949
	sample_idx += sample_group * MCS_GROUP_RATES;
950

951 952 953
	/*
	 * Sampling might add some overhead (RTS, no aggregation)
	 * to the frame. Hence, don't use sampling for the currently
954
	 * used rates.
955
	 */
956 957
	if (sample_idx == mi->max_tp_rate[0] ||
	    sample_idx == mi->max_tp_rate[1] ||
958
	    sample_idx == mi->max_prob_rate)
959
		return -1;
960

961
	/*
962 963
	 * Do not sample if the probability is already higher than 95%
	 * to avoid wasting airtime.
964
	 */
965
	if (mr->probability > MINSTREL_FRAC(95, 100))
966
		return -1;
967 968 969 970 971

	/*
	 * Make sure that lower rates get sampled only occasionally,
	 * if the link is working perfectly.
	 */
972 973 974

	cur_max_tp_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
		MCS_GROUP_RATES].streams;
975
	sample_dur = minstrel_get_duration(sample_idx);
976 977
	if (sample_dur >= minstrel_get_duration(mi->max_tp_rate[1]) &&
	    (cur_max_tp_streams - 1 <
978 979
	     minstrel_mcs_groups[sample_group].streams ||
	     sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
980
		if (mr->sample_skipped < 20)
981
			return -1;
982 983

		if (mi->sample_slow++ > 2)
984
			return -1;
985
	}
986
	mi->sample_tries--;
987 988 989 990

	return sample_idx;
}

991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006
static void
minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
				    struct minstrel_ht_sta *mi, bool val)
{
	u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;

	if (!supported || !mi->cck_supported_short)
		return;

	if (supported & (mi->cck_supported_short << (val * 4)))
		return;

	supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
	mi->groups[MINSTREL_CCK_GROUP].supported = supported;
}

1007 1008 1009 1010
static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
                     struct ieee80211_tx_rate_control *txrc)
{
1011
	const struct mcs_group *sample_group;
1012
	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
1013
	struct ieee80211_tx_rate *rate = &info->status.rates[0];
1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024
	struct minstrel_ht_sta_priv *msp = priv_sta;
	struct minstrel_ht_sta *mi = &msp->ht;
	struct minstrel_priv *mp = priv;
	int sample_idx;

	if (rate_control_send_low(sta, priv_sta, txrc))
		return;

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

1025 1026 1027 1028
	if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
	    mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
		minstrel_aggr_check(sta, txrc->skb);

1029
	info->flags |= mi->tx_flags;
1030
	minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
1031

1032 1033 1034 1035 1036
#ifdef CONFIG_MAC80211_DEBUGFS
	if (mp->fixed_rate_idx != -1)
		return;
#endif

1037 1038
	/* Don't use EAPOL frames for sampling on non-mrr hw */
	if (mp->hw->max_rates == 1 &&
1039
	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
1040 1041 1042
		sample_idx = -1;
	else
		sample_idx = minstrel_get_sample_rate(mp, mi);
1043

1044 1045 1046 1047 1048 1049 1050
	mi->total_packets++;

	/* wraparound */
	if (mi->total_packets == ~0) {
		mi->total_packets = 0;
		mi->sample_packets = 0;
	}
1051 1052 1053 1054 1055 1056

	if (sample_idx < 0)
		return;

	sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
1057 1058 1059 1060 1061
	rate->count = 1;

	if (sample_idx / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
		int idx = sample_idx % ARRAY_SIZE(mp->cck_rates);
		rate->idx = mp->cck_rates[idx];
1062 1063 1064
	} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
		ieee80211_rate_set_vht(rate, sample_idx % MCS_GROUP_RATES,
				       sample_group->streams);
1065 1066 1067
	} else {
		rate->idx = sample_idx % MCS_GROUP_RATES +
			    (sample_group->streams - 1) * 8;
1068 1069
	}

1070
	rate->flags = sample_group->flags;
1071 1072
}

1073 1074 1075 1076 1077 1078 1079 1080 1081 1082
static void
minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
		       struct ieee80211_supported_band *sband,
		       struct ieee80211_sta *sta)
{
	int i;

	if (sband->band != IEEE80211_BAND_2GHZ)
		return;

1083 1084 1085
	if (!(mp->hw->flags & IEEE80211_HW_SUPPORTS_HT_CCK_RATES))
		return;

1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
	mi->cck_supported = 0;
	mi->cck_supported_short = 0;
	for (i = 0; i < 4; i++) {
		if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
			continue;

		mi->cck_supported |= BIT(i);
		if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
			mi->cck_supported_short |= BIT(i);
	}

	mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
}

1100 1101
static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,