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linux/net/mac80211/rc80211_minstrel_ht.c

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/*
* Copyright (C) 2010-2013 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/moduleparam.h>
#include <linux/ieee80211.h>
#include <net/mac80211.h>
#include "rate.h"
#include "rc80211_minstrel.h"
#include "rc80211_minstrel_ht.h"
#define AVG_AMPDU_SIZE 16
#define AVG_PKT_SIZE 1200
/* Number of bits for an average sized packet */
#define MCS_NBITS ((AVG_PKT_SIZE * AVG_AMPDU_SIZE) << 3)
/* Number of symbols for a packet with (bps) bits per symbol */
#define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))
/* Transmission time (nanoseconds) for a packet containing (syms) symbols */
#define MCS_SYMBOL_TIME(sgi, syms) \
(sgi ? \
((syms) * 18000 + 4000) / 5 : /* syms * 3.6 us */ \
((syms) * 1000) << 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))) / AVG_AMPDU_SIZE)
#define BW_20 0
#define BW_40 1
#define BW_80 2
/*
* Define group sort order: HT40 -> SGI -> #streams
*/
#define GROUP_IDX(_streams, _sgi, _ht40) \
MINSTREL_HT_GROUP_0 + \
MINSTREL_MAX_STREAMS * 2 * _ht40 + \
MINSTREL_MAX_STREAMS * _sgi + \
_streams - 1
/* MCS rate information for an MCS group */
#define MCS_GROUP(_streams, _sgi, _ht40) \
[GROUP_IDX(_streams, _sgi, _ht40)] = { \
.streams = _streams, \
.flags = \
IEEE80211_TX_RC_MCS | \
(_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) \
} \
}
#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)) \
} \
}
#define CCK_DURATION(_bitrate, _short, _len) \
(1000 * (10 /* SIFS */ + \
(_short ? 72 + 24 : 144 + 48) + \
(8 * (_len + 4) * 10) / (_bitrate)))
#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)
#define CCK_GROUP \
[MINSTREL_CCK_GROUP] = { \
.streams = 0, \
.flags = 0, \
.duration = { \
CCK_DURATION_LIST(false), \
CCK_DURATION_LIST(true) \
} \
}
#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
/*
* 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.
*
* Sortorder has to be fixed for GROUP_IDX macro to be applicable:
* BW -> SGI -> #streams
*/
const struct mcs_group minstrel_mcs_groups[] = {
MCS_GROUP(1, 0, BW_20),
MCS_GROUP(2, 0, BW_20),
#if MINSTREL_MAX_STREAMS >= 3
MCS_GROUP(3, 0, BW_20),
#endif
MCS_GROUP(1, 1, BW_20),
MCS_GROUP(2, 1, BW_20),
#if MINSTREL_MAX_STREAMS >= 3
MCS_GROUP(3, 1, BW_20),
#endif
MCS_GROUP(1, 0, BW_40),
MCS_GROUP(2, 0, BW_40),
#if MINSTREL_MAX_STREAMS >= 3
MCS_GROUP(3, 0, BW_40),
#endif
MCS_GROUP(1, 1, BW_40),
MCS_GROUP(2, 1, BW_40),
#if MINSTREL_MAX_STREAMS >= 3
MCS_GROUP(3, 1, BW_40),
#endif
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
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
};
static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
static void
minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
/*
* 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;
}
/*
* Look up an MCS group index based on mac80211 rate information
*/
static int
minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
{
return GROUP_IDX((rate->idx / 8) + 1,
!!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
!!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
}
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));
}
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);
idx = rate->idx % 8;
} else if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
group = minstrel_vht_get_group_idx(rate);
idx = ieee80211_rate_get_vht_mcs(rate);
} 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];
}
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];
}
/*
* Return current throughput based on the average A-MPDU length, taking into
* account the expected number of retransmissions and their expected length
*/
int
minstrel_ht_get_tp_avg(struct minstrel_ht_sta *mi, int group, int rate,
int prob_ewma)
{
unsigned int nsecs = 0;
/* do not account throughput if sucess prob is below 10% */
if (prob_ewma < MINSTREL_FRAC(10, 100))
return 0;
if (group != MINSTREL_CCK_GROUP)
nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
nsecs += minstrel_mcs_groups[group].duration[rate];
/*
* For the throughput calculation, limit the probability value to 90% to
* account for collision related packet error rate fluctuation
* (prob is scaled - see MINSTREL_FRAC above)
*/
if (prob_ewma > MINSTREL_FRAC(90, 100))
return MINSTREL_TRUNC(100000 * ((MINSTREL_FRAC(90, 100) * 1000)
/ nsecs));
else
return MINSTREL_TRUNC(100000 * ((prob_ewma * 1000) / nsecs));
}
/*
* 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
minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
u16 *tp_list)
{
int cur_group, cur_idx, cur_tp_avg, cur_prob;
int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
int j = MAX_THR_RATES;
cur_group = index / MCS_GROUP_RATES;
cur_idx = index % MCS_GROUP_RATES;
cur_prob = mi->groups[cur_group].rates[cur_idx].prob_ewma;
cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx, cur_prob);
do {
tmp_group = tp_list[j - 1] / MCS_GROUP_RATES;
tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES;
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx,
tmp_prob);
if (cur_tp_avg < tmp_tp_avg ||
(cur_tp_avg == tmp_tp_avg && cur_prob <= tmp_prob))
break;
j--;
} while (j > 0);
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
minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 index)
{
struct minstrel_mcs_group_data *mg;
struct minstrel_rate_stats *mrs;
int tmp_group, tmp_idx, tmp_tp_avg, tmp_prob;
int max_tp_group, cur_tp_avg, cur_group, cur_idx;
int max_gpr_group, max_gpr_idx;
int max_gpr_tp_avg, max_gpr_prob;
cur_group = index / MCS_GROUP_RATES;
cur_idx = index % MCS_GROUP_RATES;
mg = &mi->groups[index / MCS_GROUP_RATES];
mrs = &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_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
tmp_tp_avg = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
/* 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 (mrs->prob_ewma > MINSTREL_FRAC(75, 100)) {
cur_tp_avg = minstrel_ht_get_tp_avg(mi, cur_group, cur_idx,
mrs->prob_ewma);
if (cur_tp_avg > tmp_tp_avg)
mi->max_prob_rate = index;
max_gpr_group = mg->max_group_prob_rate / MCS_GROUP_RATES;
max_gpr_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
max_gpr_prob = mi->groups[max_gpr_group].rates[max_gpr_idx].prob_ewma;
max_gpr_tp_avg = minstrel_ht_get_tp_avg(mi, max_gpr_group,
max_gpr_idx,
max_gpr_prob);
if (cur_tp_avg > max_gpr_tp_avg)
mg->max_group_prob_rate = index;
} else {
if (mrs->prob_ewma > tmp_prob)
mi->max_prob_rate = index;
if (mrs->prob_ewma > mg->rates[mg->max_group_prob_rate].prob_ewma)
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,
u16 tmp_mcs_tp_rate[MAX_THR_RATES],
u16 tmp_cck_tp_rate[MAX_THR_RATES])
{
unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp, tmp_prob;
int i;
tmp_group = tmp_cck_tp_rate[0] / MCS_GROUP_RATES;
tmp_idx = tmp_cck_tp_rate[0] % MCS_GROUP_RATES;
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
tmp_cck_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
tmp_group = tmp_mcs_tp_rate[0] / MCS_GROUP_RATES;
tmp_idx = tmp_mcs_tp_rate[0] % MCS_GROUP_RATES;
tmp_prob = mi->groups[tmp_group].rates[tmp_idx].prob_ewma;
tmp_mcs_tp = minstrel_ht_get_tp_avg(mi, tmp_group, tmp_idx, tmp_prob);
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;
int tmp_max_streams, group, tmp_idx, tmp_prob;
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;
tmp_idx = mg->max_group_prob_rate % MCS_GROUP_RATES;
tmp_prob = mi->groups[group].rates[tmp_idx].prob_ewma;
if (tmp_tp < minstrel_ht_get_tp_avg(mi, group, tmp_idx, tmp_prob) &&
(minstrel_mcs_groups[group].streams < tmp_max_streams)) {
mi->max_prob_rate = mg->max_group_prob_rate;
tmp_tp = minstrel_ht_get_tp_avg(mi, group,
tmp_idx,
tmp_prob);
}
}
}
/*
* 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 75%, 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 *mrs;
int group, i, j, cur_prob;
u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
u16 tmp_cck_tp_rate[MAX_THR_RATES], 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;
/* Initialize global rate indexes */
for(j = 0; j < MAX_THR_RATES; j++){
tmp_mcs_tp_rate[j] = 0;
tmp_cck_tp_rate[j] = 0;
}
/* Find best rate sets within all MCS groups*/
for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
mg = &mi->groups[group];
if (!mg->supported)
continue;
mi->sample_count++;
/* (re)Initialize group rate indexes */
for(j = 0; j < MAX_THR_RATES; j++)
tmp_group_tp_rate[j] = group;
for (i = 0; i < MCS_GROUP_RATES; i++) {
if (!(mg->supported & BIT(i)))
continue;
index = MCS_GROUP_RATES * group + i;
mrs = &mg->rates[i];
mrs->retry_updated = false;
minstrel_calc_rate_stats(mrs);
cur_prob = mrs->prob_ewma;
if (minstrel_ht_get_tp_avg(mi, group, i, cur_prob) == 0)
continue;
/* 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);
}
/* Find max throughput rate set within a group */
minstrel_ht_sort_best_tp_rates(mi, index,
tmp_group_tp_rate);
/* Find max probability rate per group and global */
minstrel_ht_set_best_prob_rate(mi, index);
}
memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
sizeof(mg->max_group_tp_rate));
}
/* 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));
/* 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;
#ifdef CONFIG_MAC80211_DEBUGFS
/* use fixed index if set */
if (mp->fixed_rate_idx != -1) {
for (i = 0; i < 4; i++)
mi->max_tp_rate[i] = mp->fixed_rate_idx;
mi->max_prob_rate = mp->fixed_rate_idx;
}
#endif
/* Reset update timer */
mi->last_stats_update = jiffies;
}
static bool
minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
{
if (rate->idx < 0)
return false;
if (!rate->count)
return false;
if (rate->flags & IEEE80211_TX_RC_MCS ||
rate->flags & IEEE80211_TX_RC_VHT_MCS)
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];
}
static void
minstrel_set_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
minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
{
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_group_tp_rate[0];
else
*idx = mi->groups[group].max_group_tp_rate[1];
break;
}
}
static void
minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
{
struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
u16 tid;
if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
return;
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;
if (likely(sta->ampdu_mlme.tid_tx[tid]))
return;
ieee80211_start_tx_ba_session(pubsta, tid, 5000);
}
static void
minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
struct ieee80211_sta *sta, void *priv_sta,
struct ieee80211_tx_info *info)
{
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;
bool last, update = false;
int i;
if (!msp->is_ht)
return mac80211_minstrel.tx_status_noskb(priv, sband, sta,
&msp->legacy, info);
/* This packet was aggregated but doesn't carry status info */
if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
!(info->flags & IEEE80211_TX_STAT_AMPDU))
return;
if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
info->status.ampdu_ack_len =
(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
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) {
mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
mi->sample_tries = 1;
mi->sample_count--;
}
if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
mi->sample_packets += info->status.ampdu_len;
last = !minstrel_ht_txstat_valid(mp, &ar[0]);
for (i = 0; !last; i++) {
last = (i == IEEE80211_TX_MAX_RATES - 1) ||
!minstrel_ht_txstat_valid(mp, &ar[i + 1]);
rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
if (last)
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[0]);
if (rate->attempts > 30 &&
MINSTREL_FRAC(rate->success, rate->attempts) <
MINSTREL_FRAC(20, 100)) {
minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
update = true;
}
rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
if (rate2->attempts > 30 &&
MINSTREL_FRAC(rate2->success, rate2->attempts) <
MINSTREL_FRAC(20, 100)) {
minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
update = true;
}
if (time_after(jiffies, mi->last_stats_update +
(mp->update_interval / 2 * HZ) / 1000)) {
update = true;
minstrel_ht_update_stats(mp, mi);
}
if (update)
minstrel_ht_update_rates(mp, mi);
}
static void
minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
int index)
{
struct minstrel_rate_stats *mrs;
const struct mcs_group *group;
unsigned int tx_time, tx_time_rtscts, tx_time_data;
unsigned int cw = mp->cw_min;
unsigned int ctime = 0;
unsigned int t_slot = 9; /* FIXME */
unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
unsigned int overhead = 0, overhead_rtscts = 0;
mrs = minstrel_get_ratestats(mi, index);
if (mrs->prob_ewma < MINSTREL_FRAC(1, 10)) {
mrs->retry_count = 1;
mrs->retry_count_rtscts = 1;
return;
}
mrs->retry_count = 2;
mrs->retry_count_rtscts = 2;
mrs->retry_updated = true;
group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
/* 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);
if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
overhead = mi->overhead;
overhead_rtscts = mi->overhead_rtscts;
}
/* Total TX time for data and Contention after first 2 tries */
tx_time = ctime + 2 * (overhead + tx_time_data);
tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
/* See how many more tries we can fit inside segment size */
do {
/* 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 + overhead + tx_time_data;
tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
if (tx_time_rtscts < mp->segment_size)
mrs->retry_count_rtscts++;
} while ((tx_time < mp->segment_size) &&
(++mrs->retry_count < mp->max_retry));
}
static void
minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
struct ieee80211_sta_rates *ratetbl, int offset, int index)
{
const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
struct minstrel_rate_stats *mrs;
u8 idx;
u16 flags = group->flags;
mrs = minstrel_get_ratestats(mi, index);
if (!mrs->retry_updated)
minstrel_calc_retransmit(mp, mi, index);
if (mrs->prob_ewma < MINSTREL_FRAC(20, 100) || !mrs->retry_count) {
ratetbl->rate[offset].count = 2;
ratetbl->rate[offset].count_rts = 2;
ratetbl->rate[offset].count_cts = 2;
} else {
ratetbl->rate[offset].count = mrs->retry_count;
ratetbl->rate[offset].count_cts = mrs->retry_count;
ratetbl->rate[offset].count_rts = mrs->retry_count_rtscts;
}
if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP)
idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
else if (flags & IEEE80211_TX_RC_VHT_MCS)
idx = ((group->streams - 1) << 4) |
((index % MCS_GROUP_RATES) & 0xF);
else
idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8;
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)
return;
/* Start with max_tp_rate[0] */
minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);
if (mp->hw->max_rates >= 3) {
/* 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]);
}
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);
}
rates->rate[i].idx = -1;
rate_control_set_rates(mp->hw, mi->sta, 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 *mrs;
struct minstrel_mcs_group_data *mg;
unsigned int sample_dur, sample_group, cur_max_tp_streams;
int sample_idx = 0;
if (mi->sample_wait > 0) {
mi->sample_wait--;
return -1;
}
if (!mi->sample_tries)
return -1;
sample_group = mi->sample_group;
mg = &mi->groups[sample_group];
sample_idx = sample_table[mg->column][mg->index];
minstrel_set_next_sample_idx(mi);
if (!(mg->supported & BIT(sample_idx)))
return -1;
mrs = &mg->rates[sample_idx];
sample_idx += sample_group * MCS_GROUP_RATES;
/*
* Sampling might add some overhead (RTS, no aggregation)
* to the frame. Hence, don't use sampling for the currently
* used rates.
*/
if (sample_idx == mi->max_tp_rate[0] ||
sample_idx == mi->max_tp_rate[1] ||
sample_idx == mi->max_prob_rate)
return -1;
/*
* Do not sample if the probability is already higher than 95%
* to avoid wasting airtime.
*/
if (mrs->prob_ewma > MINSTREL_FRAC(95, 100))
return -1;
/*
* Make sure that lower rates get sampled only occasionally,
* if the link is working perfectly.
*/
cur_max_tp_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
MCS_GROUP_RATES].streams;
sample_dur = minstrel_get_duration(sample_idx);
if (sample_dur >= minstrel_get_duration(mi->max_tp_rate[1]) &&
(cur_max_tp_streams - 1 <
minstrel_mcs_groups[sample_group].streams ||
sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
if (mrs->sample_skipped < 20)
return -1;
if (mi->sample_slow++ > 2)
return -1;
}
mi->sample_tries--;
return sample_idx;
}
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;
}
static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
struct ieee80211_tx_rate_control *txrc)
{
const struct mcs_group *sample_group;
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
struct ieee80211_tx_rate *rate = &info->status.rates[0];
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);
if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
minstrel_aggr_check(sta, txrc->skb);
info->flags |= mi->tx_flags;
minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
#ifdef CONFIG_MAC80211_DEBUGFS
if (mp->fixed_rate_idx != -1)
return;
#endif
/* Don't use EAPOL frames for sampling on non-mrr hw */
if (mp->hw->max_rates == 1 &&
(info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
sample_idx = -1;
else
sample_idx = minstrel_get_sample_rate(mp, mi);
mi->total_packets++;
/* wraparound */
if (mi->total_packets == ~0) {
mi->total_packets = 0;
mi->sample_packets = 0;
}
if (sample_idx < 0)
return;
sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
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];
} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
ieee80211_rate_set_vht(rate, sample_idx % MCS_GROUP_RATES,
sample_group->streams);
} else {
rate->idx = sample_idx % MCS_GROUP_RATES +
(sample_group->streams - 1) * 8;
}
rate->flags = sample_group->flags;
}
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;
if (!ieee80211_hw_check(mp->hw, SUPPORTS_HT_CCK_RATES))
return;
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;
}
static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
struct cfg80211_chan_def *chandef,
struct ieee80211_sta *sta, void *priv_sta)
{
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;
u16 sta_cap = sta->ht_cap.cap;
struct ieee80211_sta_vht_cap *vht_cap = &sta->vht_cap;
int use_vht;
int n_supported = 0;
int ack_dur;
int stbc;
int i;
/* fall back to the old minstrel for legacy stations */
if (!sta->ht_cap.ht_supported)
goto use_legacy;
BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != MINSTREL_GROUPS_NB);
#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
if (vht_cap->vht_supported)
use_vht = vht_cap->vht_mcs.tx_mcs_map != cpu_to_le16(~0);
else
#endif
use_vht = 0;
msp->is_ht = true;
memset(mi, 0, sizeof(*mi));
mi->sta = sta;
mi->last_stats_update = jiffies;
ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0);
mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0);
mi->overhead += 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;
/* TODO tx_flags for vht - ATM the RC API is not fine-grained enough */
if (!use_vht) {
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;
}
for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
u32 gflags = minstrel_mcs_groups[i].flags;
int bw, nss;
mi->groups[i].supported = 0;
if (i == MINSTREL_CCK_GROUP) {
minstrel_ht_update_cck(mp, mi, sband, sta);
continue;
}
if (gflags & IEEE80211_TX_RC_SHORT_GI) {
if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
continue;
} else {
if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
continue;
}
}
if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
sta->bandwidth < IEEE80211_STA_RX_BW_40)
continue;
nss = minstrel_mcs_groups[i].streams;
/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
if (sta->smps_mode == IEEE80211_SMPS_STATIC && nss > 1)
continue;
/* HT rate */
if (gflags & IEEE80211_TX_RC_MCS) {
#ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
if (use_vht && minstrel_vht_only)
continue;
#endif
mi->groups[i].supported = mcs->rx_mask[nss - 1];
if (mi->groups[i].supported)
n_supported++;
continue;
}
/* VHT rate */
if (!vht_cap->vht_supported ||
WARN_ON(!(gflags & IEEE80211_TX_RC_VHT_MCS)) ||
WARN_ON(gflags & IEEE80211_TX_RC_160_MHZ_WIDTH))
continue;
if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH) {
if (sta->bandwidth < IEEE80211_STA_RX_BW_80 ||
((gflags & IEEE80211_TX_RC_SHORT_GI) &&
!(vht_cap->cap & IEEE80211_VHT_CAP_SHORT_GI_80))) {
continue;
}
}
if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH)
bw = BW_40;
else if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH)
bw = BW_80;
else
bw = BW_20;
mi->groups[i].supported = minstrel_get_valid_vht_rates(bw, nss,
vht_cap->vht_mcs.tx_mcs_map);
if (mi->groups[i].supported)
n_supported++;
}
if (!n_supported)
goto use_legacy;
/* create an initial rate table with the lowest supported rates */
minstrel_ht_update_stats(mp, mi);
minstrel_ht_update_rates(mp, mi);
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, chandef, sta,
&msp->legacy);
}
static void
minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
struct cfg80211_chan_def *chandef,
struct ieee80211_sta *sta, void *priv_sta)
{
minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
}
static void
minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
struct cfg80211_chan_def *chandef,
struct ieee80211_sta *sta, void *priv_sta,
u32 changed)
{
minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
}
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(*msp), 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:
kfree(msp->ratelist);
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 u32 minstrel_ht_get_expected_throughput(void *priv_sta)
{
struct minstrel_ht_sta_priv *msp = priv_sta;
struct minstrel_ht_sta *mi = &msp->ht;
int i, j, prob, tp_avg;
if (!msp->is_ht)
return mac80211_minstrel.get_expected_throughput(priv_sta);
i = mi->max_tp_rate[0] / MCS_GROUP_RATES;
j = mi->max_tp_rate[0] % MCS_GROUP_RATES;
prob = mi->groups[i].rates[j].prob_ewma;
/* convert tp_avg from pkt per second in kbps */
tp_avg = minstrel_ht_get_tp_avg(mi, i, j, prob) * AVG_PKT_SIZE * 8 / 1024;
return tp_avg;
}
static const struct rate_control_ops mac80211_minstrel_ht = {
.name = "minstrel_ht",
.tx_status_noskb = 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
.get_expected_throughput = minstrel_ht_get_expected_throughput,
};
static void __init 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++) {
prandom_bytes(rnd, sizeof(rnd));
for (i = 0; i < MCS_GROUP_RATES; i++) {
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);
}
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