2 * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
8 #include <linux/netdevice.h>
9 #include <linux/types.h>
10 #include <linux/skbuff.h>
11 #include <linux/debugfs.h>
12 #include <linux/random.h>
13 #include <linux/ieee80211.h>
14 #include <net/mac80211.h>
16 #include "rc80211_minstrel.h"
17 #include "rc80211_minstrel_ht.h"
19 #define AVG_PKT_SIZE 1200
20 #define SAMPLE_COLUMNS 10
23 /* Number of bits for an average sized packet */
24 #define MCS_NBITS (AVG_PKT_SIZE << 3)
26 /* Number of symbols for a packet with (bps) bits per symbol */
27 #define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
29 /* Transmission time for a packet containing (syms) symbols */
30 #define MCS_SYMBOL_TIME(sgi, syms) \
32 ((syms) * 18 + 4) / 5 : /* syms * 3.6 us */ \
33 (syms) << 2 /* syms * 4 us */ \
36 /* Transmit duration for the raw data part of an average sized packet */
37 #define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
39 /* MCS rate information for an MCS group */
40 #define MCS_GROUP(_streams, _sgi, _ht40) { \
41 .streams = _streams, \
43 (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
44 (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
46 MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \
47 MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \
48 MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \
49 MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \
50 MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \
51 MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \
52 MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \
53 MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \
58 * To enable sufficiently targeted rate sampling, MCS rates are divided into
59 * groups, based on the number of streams and flags (HT40, SGI) that they
62 const struct mcs_group minstrel_mcs_groups[] = {
65 #if MINSTREL_MAX_STREAMS >= 3
71 #if MINSTREL_MAX_STREAMS >= 3
77 #if MINSTREL_MAX_STREAMS >= 3
83 #if MINSTREL_MAX_STREAMS >= 3
88 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
91 * Perform EWMA (Exponentially Weighted Moving Average) calculation
94 minstrel_ewma(int old, int new, int weight)
96 return (new * (100 - weight) + old * weight) / 100;
100 * Look up an MCS group index based on mac80211 rate information
103 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
105 int streams = (rate->idx / MCS_GROUP_RATES) + 1;
106 u32 flags = IEEE80211_TX_RC_SHORT_GI | IEEE80211_TX_RC_40_MHZ_WIDTH;
109 for (i = 0; i < ARRAY_SIZE(minstrel_mcs_groups); i++) {
110 if (minstrel_mcs_groups[i].streams != streams)
112 if (minstrel_mcs_groups[i].flags != (rate->flags & flags))
122 static inline struct minstrel_rate_stats *
123 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
125 return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
130 * Recalculate success probabilities and counters for a rate using EWMA
133 minstrel_calc_rate_ewma(struct minstrel_priv *mp, struct minstrel_rate_stats *mr)
135 if (unlikely(mr->attempts > 0)) {
136 mr->sample_skipped = 0;
137 mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
139 mr->probability = mr->cur_prob;
141 mr->probability = minstrel_ewma(mr->probability,
142 mr->cur_prob, EWMA_LEVEL);
143 mr->att_hist += mr->attempts;
144 mr->succ_hist += mr->success;
146 mr->sample_skipped++;
148 mr->last_success = mr->success;
149 mr->last_attempts = mr->attempts;
155 * Calculate throughput based on the average A-MPDU length, taking into account
156 * the expected number of retransmissions and their expected length
159 minstrel_ht_calc_tp(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
162 struct minstrel_rate_stats *mr;
165 mr = &mi->groups[group].rates[rate];
167 if (mr->probability < MINSTREL_FRAC(1, 10)) {
172 usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
173 usecs += minstrel_mcs_groups[group].duration[rate];
174 mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
178 * Update rate statistics and select new primary rates
180 * Rules for rate selection:
181 * - max_prob_rate must use only one stream, as a tradeoff between delivery
182 * probability and throughput during strong fluctuations
183 * - as long as the max prob rate has a probability of more than 3/4, pick
184 * higher throughput rates, even if the probablity is a bit lower
187 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
189 struct minstrel_mcs_group_data *mg;
190 struct minstrel_rate_stats *mr;
191 int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
194 if (mi->ampdu_packets > 0) {
195 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
196 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
198 mi->ampdu_packets = 0;
202 mi->sample_count = 0;
204 mi->max_tp_rate2 = 0;
205 mi->max_prob_rate = 0;
207 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
213 mg = &mi->groups[group];
218 mg->max_tp_rate2 = 0;
219 mg->max_prob_rate = 0;
222 for (i = 0; i < MCS_GROUP_RATES; i++) {
223 if (!(mg->supported & BIT(i)))
227 mr->retry_updated = false;
228 index = MCS_GROUP_RATES * group + i;
229 minstrel_calc_rate_ewma(mp, mr);
230 minstrel_ht_calc_tp(mp, mi, group, i);
235 /* ignore the lowest rate of each single-stream group */
236 if (!i && minstrel_mcs_groups[group].streams == 1)
239 if ((mr->cur_tp > cur_prob_tp && mr->probability >
240 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
241 mg->max_prob_rate = index;
242 cur_prob = mr->probability;
243 cur_prob_tp = mr->cur_tp;
246 if (mr->cur_tp > cur_tp) {
247 swap(index, mg->max_tp_rate);
249 mr = minstrel_get_ratestats(mi, index);
252 if (index >= mg->max_tp_rate)
255 if (mr->cur_tp > cur_tp2) {
256 mg->max_tp_rate2 = index;
257 cur_tp2 = mr->cur_tp;
262 /* try to sample up to half of the availble rates during each interval */
263 mi->sample_count *= 4;
269 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
270 mg = &mi->groups[group];
274 mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
275 if (cur_prob_tp < mr->cur_tp &&
276 minstrel_mcs_groups[group].streams == 1) {
277 mi->max_prob_rate = mg->max_prob_rate;
278 cur_prob = mr->cur_prob;
279 cur_prob_tp = mr->cur_tp;
282 mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
283 if (cur_tp < mr->cur_tp) {
284 mi->max_tp_rate = mg->max_tp_rate;
288 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
289 if (cur_tp2 < mr->cur_tp) {
290 mi->max_tp_rate2 = mg->max_tp_rate2;
291 cur_tp2 = mr->cur_tp;
295 mi->stats_update = jiffies;
299 minstrel_ht_txstat_valid(struct ieee80211_tx_rate *rate)
307 return !!(rate->flags & IEEE80211_TX_RC_MCS);
311 minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
313 struct minstrel_mcs_group_data *mg;
317 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
318 mg = &mi->groups[mi->sample_group];
323 if (++mg->index >= MCS_GROUP_RATES) {
325 if (++mg->column >= ARRAY_SIZE(sample_table))
333 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
336 int group, orig_group;
338 orig_group = group = *idx / MCS_GROUP_RATES;
342 if (!mi->groups[group].supported)
345 if (minstrel_mcs_groups[group].streams >
346 minstrel_mcs_groups[orig_group].streams)
350 *idx = mi->groups[group].max_tp_rate;
352 *idx = mi->groups[group].max_tp_rate2;
358 minstrel_aggr_check(struct minstrel_priv *mp, struct ieee80211_sta *pubsta, struct sk_buff *skb)
360 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
361 struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
364 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
367 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
370 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
371 if (likely(sta->ampdu_mlme.tid_tx[tid]))
374 ieee80211_start_tx_ba_session(pubsta, tid);
378 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
379 struct ieee80211_sta *sta, void *priv_sta,
382 struct minstrel_ht_sta_priv *msp = priv_sta;
383 struct minstrel_ht_sta *mi = &msp->ht;
384 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
385 struct ieee80211_tx_rate *ar = info->status.rates;
386 struct minstrel_rate_stats *rate, *rate2;
387 struct minstrel_priv *mp = priv;
393 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
395 /* This packet was aggregated but doesn't carry status info */
396 if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
397 !(info->flags & IEEE80211_TX_STAT_AMPDU))
400 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
401 info->status.ampdu_ack_len =
402 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
403 info->status.ampdu_len = 1;
407 mi->ampdu_len += info->status.ampdu_len;
409 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
410 mi->sample_wait = 4 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
411 mi->sample_tries = 3;
415 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE) {
416 mi->sample_packets += info->status.ampdu_len;
417 minstrel_next_sample_idx(mi);
420 for (i = 0; !last; i++) {
421 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
422 !minstrel_ht_txstat_valid(&ar[i + 1]);
424 if (!minstrel_ht_txstat_valid(&ar[i]))
427 group = minstrel_ht_get_group_idx(&ar[i]);
428 rate = &mi->groups[group].rates[ar[i].idx % 8];
431 rate->success += info->status.ampdu_ack_len;
433 rate->attempts += ar[i].count * info->status.ampdu_len;
437 * check for sudden death of spatial multiplexing,
438 * downgrade to a lower number of streams if necessary.
440 rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
441 if (rate->attempts > 30 &&
442 MINSTREL_FRAC(rate->success, rate->attempts) <
443 MINSTREL_FRAC(20, 100))
444 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
446 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
447 if (rate2->attempts > 30 &&
448 MINSTREL_FRAC(rate2->success, rate2->attempts) <
449 MINSTREL_FRAC(20, 100))
450 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
452 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
453 minstrel_ht_update_stats(mp, mi);
454 minstrel_aggr_check(mp, sta, skb);
459 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
462 struct minstrel_rate_stats *mr;
463 const struct mcs_group *group;
464 unsigned int tx_time, tx_time_rtscts, tx_time_data;
465 unsigned int cw = mp->cw_min;
466 unsigned int t_slot = 9; /* FIXME */
467 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
469 mr = minstrel_get_ratestats(mi, index);
470 if (mr->probability < MINSTREL_FRAC(1, 10)) {
472 mr->retry_count_rtscts = 1;
477 mr->retry_count_rtscts = 2;
478 mr->retry_updated = true;
480 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
481 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len;
482 tx_time = 2 * (t_slot + mi->overhead + tx_time_data);
483 tx_time_rtscts = 2 * (t_slot + mi->overhead_rtscts + tx_time_data);
486 cw = min(cw, mp->cw_max);
487 tx_time += cw + t_slot + mi->overhead;
488 tx_time_rtscts += cw + t_slot + mi->overhead_rtscts;
489 if (tx_time_rtscts < mp->segment_size)
490 mr->retry_count_rtscts++;
491 } while ((tx_time < mp->segment_size) &&
492 (++mr->retry_count < mp->max_retry));
497 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
498 struct ieee80211_tx_rate *rate, int index,
499 struct ieee80211_tx_rate_control *txrc,
500 bool sample, bool rtscts)
502 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
503 struct minstrel_rate_stats *mr;
505 mr = minstrel_get_ratestats(mi, index);
506 if (!mr->retry_updated)
507 minstrel_calc_retransmit(mp, mi, index);
509 if (mr->probability < MINSTREL_FRAC(20, 100))
512 rate->count = mr->retry_count_rtscts;
514 rate->count = mr->retry_count;
516 rate->flags = IEEE80211_TX_RC_MCS | group->flags;
517 if (txrc->short_preamble)
518 rate->flags |= IEEE80211_TX_RC_USE_SHORT_PREAMBLE;
519 if (txrc->rts || rtscts)
520 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
521 rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
525 minstrel_get_duration(int index)
527 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
528 return group->duration[index % MCS_GROUP_RATES];
532 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
534 struct minstrel_rate_stats *mr;
535 struct minstrel_mcs_group_data *mg;
538 if (mi->sample_wait > 0) {
543 if (!mi->sample_tries)
547 mg = &mi->groups[mi->sample_group];
548 sample_idx = sample_table[mg->column][mg->index];
549 mr = &mg->rates[sample_idx];
550 sample_idx += mi->sample_group * MCS_GROUP_RATES;
553 * When not using MRR, do not sample if the probability is already
554 * higher than 95% to avoid wasting airtime
556 if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
560 * Make sure that lower rates get sampled only occasionally,
561 * if the link is working perfectly.
563 if (minstrel_get_duration(sample_idx) >
564 minstrel_get_duration(mi->max_tp_rate)) {
565 if (mr->sample_skipped < 10)
568 if (mi->sample_slow++ > 2)
575 minstrel_next_sample_idx(mi);
580 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
581 struct ieee80211_tx_rate_control *txrc)
583 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
584 struct ieee80211_tx_rate *ar = info->status.rates;
585 struct minstrel_ht_sta_priv *msp = priv_sta;
586 struct minstrel_ht_sta *mi = &msp->ht;
587 struct minstrel_priv *mp = priv;
590 if (rate_control_send_low(sta, priv_sta, txrc))
594 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
596 info->flags |= mi->tx_flags;
597 sample_idx = minstrel_get_sample_rate(mp, mi);
598 if (sample_idx >= 0) {
599 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
601 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
603 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
605 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
607 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
610 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate, txrc, false, true);
618 if (mi->total_packets == ~0) {
619 mi->total_packets = 0;
620 mi->sample_packets = 0;
625 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
626 struct ieee80211_sta *sta, void *priv_sta,
627 enum nl80211_channel_type oper_chan_type)
629 struct minstrel_priv *mp = priv;
630 struct minstrel_ht_sta_priv *msp = priv_sta;
631 struct minstrel_ht_sta *mi = &msp->ht;
632 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
633 struct ieee80211_local *local = hw_to_local(mp->hw);
634 u16 sta_cap = sta->ht_cap.cap;
639 /* fall back to the old minstrel for legacy stations */
640 if (!sta->ht_cap.ht_supported) {
642 memset(&msp->legacy, 0, sizeof(msp->legacy));
643 msp->legacy.r = msp->ratelist;
644 msp->legacy.sample_table = msp->sample_table;
645 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
648 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
649 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
652 memset(mi, 0, sizeof(*mi));
653 mi->stats_update = jiffies;
655 ack_dur = ieee80211_frame_duration(local, 10, 60, 1, 1);
656 mi->overhead = ieee80211_frame_duration(local, 0, 60, 1, 1) + ack_dur;
657 mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
659 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
661 /* When using MRR, sample more on the first attempt, without delay */
663 mi->sample_count = 16;
666 mi->sample_count = 8;
669 mi->sample_tries = 4;
671 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
672 IEEE80211_HT_CAP_RX_STBC_SHIFT;
673 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
675 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
676 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
678 if (oper_chan_type != NL80211_CHAN_HT40MINUS &&
679 oper_chan_type != NL80211_CHAN_HT40PLUS)
680 sta_cap &= ~IEEE80211_HT_CAP_SUP_WIDTH_20_40;
682 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
685 mi->groups[i].supported = 0;
686 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
687 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
688 req |= IEEE80211_HT_CAP_SGI_40;
690 req |= IEEE80211_HT_CAP_SGI_20;
693 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
694 req |= IEEE80211_HT_CAP_SUP_WIDTH_20_40;
696 if ((sta_cap & req) != req)
699 mi->groups[i].supported =
700 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
705 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
706 struct ieee80211_sta *sta, void *priv_sta)
708 struct minstrel_priv *mp = priv;
710 minstrel_ht_update_caps(priv, sband, sta, priv_sta, mp->hw->conf.channel_type);
714 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
715 struct ieee80211_sta *sta, void *priv_sta,
716 u32 changed, enum nl80211_channel_type oper_chan_type)
718 minstrel_ht_update_caps(priv, sband, sta, priv_sta, oper_chan_type);
722 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
724 struct ieee80211_supported_band *sband;
725 struct minstrel_ht_sta_priv *msp;
726 struct minstrel_priv *mp = priv;
727 struct ieee80211_hw *hw = mp->hw;
731 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
732 sband = hw->wiphy->bands[i];
733 if (sband && sband->n_bitrates > max_rates)
734 max_rates = sband->n_bitrates;
737 msp = kzalloc(sizeof(struct minstrel_ht_sta), gfp);
741 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
745 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
746 if (!msp->sample_table)
752 kfree(msp->ratelist);
759 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
761 struct minstrel_ht_sta_priv *msp = priv_sta;
763 kfree(msp->sample_table);
764 kfree(msp->ratelist);
769 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
771 return mac80211_minstrel.alloc(hw, debugfsdir);
775 minstrel_ht_free(void *priv)
777 mac80211_minstrel.free(priv);
780 static struct rate_control_ops mac80211_minstrel_ht = {
781 .name = "minstrel_ht",
782 .tx_status = minstrel_ht_tx_status,
783 .get_rate = minstrel_ht_get_rate,
784 .rate_init = minstrel_ht_rate_init,
785 .rate_update = minstrel_ht_rate_update,
786 .alloc_sta = minstrel_ht_alloc_sta,
787 .free_sta = minstrel_ht_free_sta,
788 .alloc = minstrel_ht_alloc,
789 .free = minstrel_ht_free,
790 #ifdef CONFIG_MAC80211_DEBUGFS
791 .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
792 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
798 init_sample_table(void)
801 u8 rnd[MCS_GROUP_RATES];
803 memset(sample_table, 0xff, sizeof(sample_table));
804 for (col = 0; col < SAMPLE_COLUMNS; col++) {
805 for (i = 0; i < MCS_GROUP_RATES; i++) {
806 get_random_bytes(rnd, sizeof(rnd));
807 new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
809 while (sample_table[col][new_idx] != 0xff)
810 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
812 sample_table[col][new_idx] = i;
818 rc80211_minstrel_ht_init(void)
821 return ieee80211_rate_control_register(&mac80211_minstrel_ht);
825 rc80211_minstrel_ht_exit(void)
827 ieee80211_rate_control_unregister(&mac80211_minstrel_ht);