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mac80211: improve the rate control API
[deliverable/linux.git] / net / mac80211 / rc80211_minstrel_ht.c
CommitLineData
ec8aa669 1/*
a0497f9f 2 * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
ec8aa669
FF		 3 *
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.
7 */
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>
15#include "rate.h"
16#include "rc80211_minstrel.h"
17#include "rc80211_minstrel_ht.h"
18
19#define AVG_PKT_SIZE 1200
ec8aa669
FF		 20
21/* Number of bits for an average sized packet */
22#define MCS_NBITS (AVG_PKT_SIZE << 3)
23
24/* Number of symbols for a packet with (bps) bits per symbol */
25#define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
26
ed97a13c 27/* Transmission time (nanoseconds) for a packet containing (syms) symbols */
ec8aa669
FF		 28#define MCS_SYMBOL_TIME(sgi, syms) \
29 (sgi ? \
ed97a13c
FF		 30 ((syms) * 18000 + 4000) / 5 : /* syms * 3.6 us */ \
31 ((syms) * 1000) << 2 /* syms * 4 us */ \
ec8aa669
FF		 32 )
33
34/* Transmit duration for the raw data part of an average sized packet */
35#define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
36
a5f69d94
HS		 37/*
38 * Define group sort order: HT40 -> SGI -> #streams
39 */
40#define GROUP_IDX(_streams, _sgi, _ht40) \
41 MINSTREL_MAX_STREAMS * 2 * _ht40 + \
42 MINSTREL_MAX_STREAMS * _sgi + \
43 _streams - 1
44
ec8aa669 45/* MCS rate information for an MCS group */
a5f69d94
HS		 46#define MCS_GROUP(_streams, _sgi, _ht40) \
47 [GROUP_IDX(_streams, _sgi, _ht40)] = { \
ec8aa669
FF		 48 .streams = _streams, \
49 .flags = \
50 (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
51 (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
52 .duration = { \
53 MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \
54 MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \
55 MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \
56 MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \
57 MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \
58 MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \
59 MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \
60 MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \
61 } \
62}
63
a0497f9f 64#define CCK_DURATION(_bitrate, _short, _len) \
ed97a13c 65 (1000 * (10 /* SIFS */ + \
a0497f9f 66 (_short ? 72 + 24 : 144 + 48 ) + \
ed97a13c 67 (8 * (_len + 4) * 10) / (_bitrate)))
a0497f9f
FF		 68
69#define CCK_ACK_DURATION(_bitrate, _short) \
70 (CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \
71 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))
72
73#define CCK_DURATION_LIST(_short) \
74 CCK_ACK_DURATION(10, _short), \
75 CCK_ACK_DURATION(20, _short), \
76 CCK_ACK_DURATION(55, _short), \
77 CCK_ACK_DURATION(110, _short)
78
79#define CCK_GROUP \
80 [MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = { \
81 .streams = 0, \
82 .duration = { \
83 CCK_DURATION_LIST(false), \
84 CCK_DURATION_LIST(true) \
85 } \
86 }
87
ec8aa669
FF		 88/*
89 * To enable sufficiently targeted rate sampling, MCS rates are divided into
90 * groups, based on the number of streams and flags (HT40, SGI) that they
91 * use.
a5f69d94
HS		 92 *
93 * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
94 * HT40 -> SGI -> #streams
ec8aa669
FF		 95 */
96const struct mcs_group minstrel_mcs_groups[] = {
97 MCS_GROUP(1, 0, 0),
98 MCS_GROUP(2, 0, 0),
99#if MINSTREL_MAX_STREAMS >= 3
100 MCS_GROUP(3, 0, 0),
101#endif
102
103 MCS_GROUP(1, 1, 0),
104 MCS_GROUP(2, 1, 0),
105#if MINSTREL_MAX_STREAMS >= 3
106 MCS_GROUP(3, 1, 0),
107#endif
108
109 MCS_GROUP(1, 0, 1),
110 MCS_GROUP(2, 0, 1),
111#if MINSTREL_MAX_STREAMS >= 3
112 MCS_GROUP(3, 0, 1),
113#endif
114
115 MCS_GROUP(1, 1, 1),
116 MCS_GROUP(2, 1, 1),
117#if MINSTREL_MAX_STREAMS >= 3
118 MCS_GROUP(3, 1, 1),
119#endif
a0497f9f
FF		 120
121 /* must be last */
122 CCK_GROUP
ec8aa669
FF		 123};
124
a0497f9f
FF		 125#define MINSTREL_CCK_GROUP (ARRAY_SIZE(minstrel_mcs_groups) - 1)
126
ec8aa669
FF		 127static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
128
ec8aa669
FF		 129/*
130 * Look up an MCS group index based on mac80211 rate information
131 */
132static int
133minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
134{
a5f69d94
HS		 135 return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
136 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
137 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
ec8aa669
FF		 138}
139
a0497f9f
FF		 140static struct minstrel_rate_stats *
141minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
142 struct ieee80211_tx_rate *rate)
143{
144 int group, idx;
145
146 if (rate->flags & IEEE80211_TX_RC_MCS) {
147 group = minstrel_ht_get_group_idx(rate);
148 idx = rate->idx % MCS_GROUP_RATES;
149 } else {
150 group = MINSTREL_CCK_GROUP;
151
152 for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
153 if (rate->idx == mp->cck_rates[idx])
154 break;
155
156 /* short preamble */
157 if (!(mi->groups[group].supported & BIT(idx)))
158 idx += 4;
159 }
160 return &mi->groups[group].rates[idx];
161}
162
ec8aa669
FF		 163static inline struct minstrel_rate_stats *
164minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
165{
166 return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
167}
168
169
170/*
171 * Recalculate success probabilities and counters for a rate using EWMA
172 */
173static void
6048d763 174minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
ec8aa669
FF		 175{
176 if (unlikely(mr->attempts > 0)) {
177 mr->sample_skipped = 0;
178 mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
179 if (!mr->att_hist)
180 mr->probability = mr->cur_prob;
181 else
182 mr->probability = minstrel_ewma(mr->probability,
183 mr->cur_prob, EWMA_LEVEL);
184 mr->att_hist += mr->attempts;
185 mr->succ_hist += mr->success;
186 } else {
187 mr->sample_skipped++;
188 }
189 mr->last_success = mr->success;
190 mr->last_attempts = mr->attempts;
191 mr->success = 0;
192 mr->attempts = 0;
193}
194
195/*
196 * Calculate throughput based on the average A-MPDU length, taking into account
197 * the expected number of retransmissions and their expected length
198 */
199static void
6048d763 200minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
ec8aa669
FF		 201{
202 struct minstrel_rate_stats *mr;
ed97a13c
FF		 203 unsigned int nsecs = 0;
204 unsigned int tp;
3e8b1eb2 205 unsigned int prob;
ec8aa669
FF		 206
207 mr = &mi->groups[group].rates[rate];
3e8b1eb2 208 prob = mr->probability;
ec8aa669 209
3e8b1eb2 210 if (prob < MINSTREL_FRAC(1, 10)) {
ec8aa669
FF		 211 mr->cur_tp = 0;
212 return;
213 }
214
3e8b1eb2
FF		 215 /*
216 * For the throughput calculation, limit the probability value to 90% to
217 * account for collision related packet error rate fluctuation
218 */
219 if (prob > MINSTREL_FRAC(9, 10))
220 prob = MINSTREL_FRAC(9, 10);
221
a0497f9f 222 if (group != MINSTREL_CCK_GROUP)
ed97a13c 223 nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
a0497f9f 224
ed97a13c
FF		 225 nsecs += minstrel_mcs_groups[group].duration[rate];
226 tp = 1000000 * ((mr->probability * 1000) / nsecs);
227
228 mr->cur_tp = MINSTREL_TRUNC(tp);
ec8aa669
FF		 229}
230
231/*
232 * Update rate statistics and select new primary rates
233 *
234 * Rules for rate selection:
235 * - max_prob_rate must use only one stream, as a tradeoff between delivery
236 * probability and throughput during strong fluctuations
237 * - as long as the max prob rate has a probability of more than 3/4, pick
238 * higher throughput rates, even if the probablity is a bit lower
239 */
240static void
241minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
242{
243 struct minstrel_mcs_group_data *mg;
244 struct minstrel_rate_stats *mr;
245 int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
246 int group, i, index;
c2eb5b0f 247 bool mi_rates_valid = false;
ec8aa669
FF		 248
249 if (mi->ampdu_packets > 0) {
250 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
251 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
252 mi->ampdu_len = 0;
253 mi->ampdu_packets = 0;
254 }
255
256 mi->sample_slow = 0;
257 mi->sample_count = 0;
ec8aa669
FF		 258
259 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
c2eb5b0f
KB		 260 bool mg_rates_valid = false;
261
ec8aa669
FF		 262 cur_prob = 0;
263 cur_prob_tp = 0;
264 cur_tp = 0;
265 cur_tp2 = 0;
266
267 mg = &mi->groups[group];
268 if (!mg->supported)
269 continue;
270
ec8aa669
FF		 271 mi->sample_count++;
272
273 for (i = 0; i < MCS_GROUP_RATES; i++) {
274 if (!(mg->supported & BIT(i)))
275 continue;
276
c2eb5b0f
KB		 277 /* initialize rates selections starting indexes */
278 if (!mg_rates_valid) {
279 mg->max_tp_rate = mg->max_tp_rate2 =
280 mg->max_prob_rate = i;
281 if (!mi_rates_valid) {
282 mi->max_tp_rate = mi->max_tp_rate2 =
283 mi->max_prob_rate = i;
284 mi_rates_valid = true;
285 }
286 mg_rates_valid = true;
287 }
288
ec8aa669
FF		 289 mr = &mg->rates[i];
290 mr->retry_updated = false;
291 index = MCS_GROUP_RATES * group + i;
6048d763
PK		 292 minstrel_calc_rate_ewma(mr);
293 minstrel_ht_calc_tp(mi, group, i);
ec8aa669
FF		 294
295 if (!mr->cur_tp)
296 continue;
297
ec8aa669
FF		 298 if ((mr->cur_tp > cur_prob_tp && mr->probability >
299 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
300 mg->max_prob_rate = index;
301 cur_prob = mr->probability;
009271f9 302 cur_prob_tp = mr->cur_tp;
ec8aa669
FF		 303 }
304
305 if (mr->cur_tp > cur_tp) {
306 swap(index, mg->max_tp_rate);
307 cur_tp = mr->cur_tp;
308 mr = minstrel_get_ratestats(mi, index);
309 }
310
311 if (index >= mg->max_tp_rate)
312 continue;
313
314 if (mr->cur_tp > cur_tp2) {
315 mg->max_tp_rate2 = index;
316 cur_tp2 = mr->cur_tp;
317 }
318 }
319 }
320
96d4ac3f
FF		 321 /* try to sample all available rates during each interval */
322 mi->sample_count *= 8;
ec8aa669
FF		 323
324 cur_prob = 0;
325 cur_prob_tp = 0;
326 cur_tp = 0;
327 cur_tp2 = 0;
328 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
329 mg = &mi->groups[group];
330 if (!mg->supported)
331 continue;
332
ec8aa669
FF		 333 mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
334 if (cur_tp < mr->cur_tp) {
89888e36
LB		 335 mi->max_tp_rate2 = mi->max_tp_rate;
336 cur_tp2 = cur_tp;
ec8aa669
FF		 337 mi->max_tp_rate = mg->max_tp_rate;
338 cur_tp = mr->cur_tp;
965237ab 339 mi->max_prob_streams = minstrel_mcs_groups[group].streams - 1;
ec8aa669
FF		 340 }
341
342 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
343 if (cur_tp2 < mr->cur_tp) {
344 mi->max_tp_rate2 = mg->max_tp_rate2;
345 cur_tp2 = mr->cur_tp;
346 }
347 }
348
965237ab
FF		 349 if (mi->max_prob_streams < 1)
350 mi->max_prob_streams = 1;
a299c6d5
FF		 351
352 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
353 mg = &mi->groups[group];
354 if (!mg->supported)
355 continue;
356 mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
357 if (cur_prob_tp < mr->cur_tp &&
965237ab 358 minstrel_mcs_groups[group].streams <= mi->max_prob_streams) {
a299c6d5
FF		 359 mi->max_prob_rate = mg->max_prob_rate;
360 cur_prob = mr->cur_prob;
361 cur_prob_tp = mr->cur_tp;
362 }
363 }
364
365
ec8aa669
FF		 366 mi->stats_update = jiffies;
367}
368
369static bool
a0497f9f 370minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
ec8aa669 371{
b79296be 372 if (rate->idx < 0)
ec8aa669
FF		 373 return false;
374
b79296be 375 if (!rate->count)
ec8aa669
FF		 376 return false;
377
a0497f9f
FF		 378 if (rate->flags & IEEE80211_TX_RC_MCS)
379 return true;
380
381 return rate->idx == mp->cck_rates[0] ||
382 rate->idx == mp->cck_rates[1] ||
383 rate->idx == mp->cck_rates[2] ||
384 rate->idx == mp->cck_rates[3];
ec8aa669
FF		 385}
386
387static void
388minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
389{
390 struct minstrel_mcs_group_data *mg;
391
392 for (;;) {
393 mi->sample_group++;
394 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
395 mg = &mi->groups[mi->sample_group];
396
397 if (!mg->supported)
398 continue;
399
400 if (++mg->index >= MCS_GROUP_RATES) {
401 mg->index = 0;
402 if (++mg->column >= ARRAY_SIZE(sample_table))
403 mg->column = 0;
404 }
405 break;
406 }
407}
408
409static void
d5ece215
JL		 410minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
411 bool primary)
ec8aa669
FF		 412{
413 int group, orig_group;
414
415 orig_group = group = *idx / MCS_GROUP_RATES;
416 while (group > 0) {
417 group--;
418
419 if (!mi->groups[group].supported)
420 continue;
421
422 if (minstrel_mcs_groups[group].streams >
423 minstrel_mcs_groups[orig_group].streams)
424 continue;
425
426 if (primary)
427 *idx = mi->groups[group].max_tp_rate;
428 else
429 *idx = mi->groups[group].max_tp_rate2;
430 break;
431 }
432}
433
434static void
6048d763 435minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
ec8aa669
FF		 436{
437 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
438 struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
439 u16 tid;
440
441 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
442 return;
443
444 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
445 return;
446
447 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
a622ab72 448 if (likely(sta->ampdu_mlme.tid_tx[tid]))
ec8aa669
FF		 449 return;
450
48124d1a
LR		 451 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
452 return;
453
bd2ce6e4 454 ieee80211_start_tx_ba_session(pubsta, tid, 5000);
ec8aa669
FF		 455}
456
457static void
458minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
459 struct ieee80211_sta *sta, void *priv_sta,
460 struct sk_buff *skb)
461{
462 struct minstrel_ht_sta_priv *msp = priv_sta;
463 struct minstrel_ht_sta *mi = &msp->ht;
464 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
465 struct ieee80211_tx_rate *ar = info->status.rates;
466 struct minstrel_rate_stats *rate, *rate2;
467 struct minstrel_priv *mp = priv;
a544ab7f 468 bool last;
a544ab7f 469 int i;
ec8aa669
FF		 470
471 if (!msp->is_ht)
472 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
473
474 /* This packet was aggregated but doesn't carry status info */
475 if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
476 !(info->flags & IEEE80211_TX_STAT_AMPDU))
477 return;
478
15d46f38
BS		 479 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
480 info->status.ampdu_ack_len =
481 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
ec8aa669
FF		 482 info->status.ampdu_len = 1;
483 }
484
485 mi->ampdu_packets++;
486 mi->ampdu_len += info->status.ampdu_len;
487
488 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
c7317e41 489 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
52c00a37 490 mi->sample_tries = 1;
ec8aa669
FF		 491 mi->sample_count--;
492 }
493
8d5eab5a 494 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
ec8aa669 495 mi->sample_packets += info->status.ampdu_len;
ec8aa669 496
a0497f9f 497 last = !minstrel_ht_txstat_valid(mp, &ar[0]);
ec8aa669
FF		 498 for (i = 0; !last; i++) {
499 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
a0497f9f 500 !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
ec8aa669 501
a0497f9f 502 rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
ec8aa669 503
15d46f38 504 if (last)
ec8aa669
FF		 505 rate->success += info->status.ampdu_ack_len;
506
507 rate->attempts += ar[i].count * info->status.ampdu_len;
508 }
509
510 /*
511 * check for sudden death of spatial multiplexing,
512 * downgrade to a lower number of streams if necessary.
513 */
514 rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
515 if (rate->attempts > 30 &&
516 MINSTREL_FRAC(rate->success, rate->attempts) <
517 MINSTREL_FRAC(20, 100))
518 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
519
520 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
ecc3d5ae
ML		 521 if (rate2->attempts > 30 &&
522 MINSTREL_FRAC(rate2->success, rate2->attempts) <
ec8aa669
FF		 523 MINSTREL_FRAC(20, 100))
524 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
525
526 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
527 minstrel_ht_update_stats(mp, mi);
a0497f9f
FF		 528 if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
529 mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
6048d763 530 minstrel_aggr_check(sta, skb);
ec8aa669
FF		 531 }
532}
533
534static void
535minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
536 int index)
537{
538 struct minstrel_rate_stats *mr;
539 const struct mcs_group *group;
540 unsigned int tx_time, tx_time_rtscts, tx_time_data;
541 unsigned int cw = mp->cw_min;
8fddddff 542 unsigned int ctime = 0;
ec8aa669
FF		 543 unsigned int t_slot = 9; /* FIXME */
544 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
a0497f9f 545 unsigned int overhead = 0, overhead_rtscts = 0;
ec8aa669
FF		 546
547 mr = minstrel_get_ratestats(mi, index);
548 if (mr->probability < MINSTREL_FRAC(1, 10)) {
549 mr->retry_count = 1;
550 mr->retry_count_rtscts = 1;
551 return;
552 }
553
554 mr->retry_count = 2;
555 mr->retry_count_rtscts = 2;
556 mr->retry_updated = true;
557
558 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
ed97a13c 559 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
8fddddff
DH		 560
561 /* Contention time for first 2 tries */
562 ctime = (t_slot * cw) >> 1;
563 cw = min((cw << 1) | 1, mp->cw_max);
564 ctime += (t_slot * cw) >> 1;
565 cw = min((cw << 1) | 1, mp->cw_max);
566
a0497f9f
FF		 567 if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
568 overhead = mi->overhead;
569 overhead_rtscts = mi->overhead_rtscts;
570 }
571
8fddddff 572 /* Total TX time for data and Contention after first 2 tries */
a0497f9f
FF		 573 tx_time = ctime + 2 * (overhead + tx_time_data);
574 tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
8fddddff
DH		 575
576 /* See how many more tries we can fit inside segment size */
ec8aa669 577 do {
8fddddff
DH		 578 /* Contention time for this try */
579 ctime = (t_slot * cw) >> 1;
580 cw = min((cw << 1) | 1, mp->cw_max);
581
582 /* Total TX time after this try */
a0497f9f
FF		 583 tx_time += ctime + overhead + tx_time_data;
584 tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
8fddddff 585
ec8aa669
FF		 586 if (tx_time_rtscts < mp->segment_size)
587 mr->retry_count_rtscts++;
588 } while ((tx_time < mp->segment_size) &&
589 (++mr->retry_count < mp->max_retry));
590}
591
592
593static void
594minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
595 struct ieee80211_tx_rate *rate, int index,
ec8aa669
FF		 596 bool sample, bool rtscts)
597{
598 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
599 struct minstrel_rate_stats *mr;
600
601 mr = minstrel_get_ratestats(mi, index);
602 if (!mr->retry_updated)
603 minstrel_calc_retransmit(mp, mi, index);
604
c7317e41
FF		 605 if (sample)
606 rate->count = 1;
607 else if (mr->probability < MINSTREL_FRAC(20, 100))
ec8aa669
FF		 608 rate->count = 2;
609 else if (rtscts)
610 rate->count = mr->retry_count_rtscts;
611 else
612 rate->count = mr->retry_count;
613
a0497f9f 614 rate->flags = 0;
9d468d22 615 if (rtscts)
ec8aa669 616 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
a0497f9f
FF		 617
618 if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
619 rate->idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
620 return;
621 }
622
623 rate->flags |= IEEE80211_TX_RC_MCS | group->flags;
ec8aa669
FF		 624 rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
625}
626
627static inline int
628minstrel_get_duration(int index)
629{
630 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
631 return group->duration[index % MCS_GROUP_RATES];
632}
633
634static int
635minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
636{
637 struct minstrel_rate_stats *mr;
638 struct minstrel_mcs_group_data *mg;
965237ab 639 unsigned int sample_dur, sample_group;
ec8aa669
FF		 640 int sample_idx = 0;
641
642 if (mi->sample_wait > 0) {
643 mi->sample_wait--;
644 return -1;
645 }
646
647 if (!mi->sample_tries)
648 return -1;
649
ec8aa669
FF		 650 mg = &mi->groups[mi->sample_group];
651 sample_idx = sample_table[mg->column][mg->index];
652 mr = &mg->rates[sample_idx];
965237ab
FF		 653 sample_group = mi->sample_group;
654 sample_idx += sample_group * MCS_GROUP_RATES;
8d5eab5a 655 minstrel_next_sample_idx(mi);
ec8aa669 656
ba6fa29c
HS		 657 /*
658 * Sampling might add some overhead (RTS, no aggregation)
659 * to the frame. Hence, don't use sampling for the currently
a0ca796c 660 * used rates.
ba6fa29c 661 */
a0ca796c
FF		 662 if (sample_idx == mi->max_tp_rate ||
663 sample_idx == mi->max_tp_rate2 ||
664 sample_idx == mi->max_prob_rate)
ba6fa29c 665 return -1;
a0ca796c 666
ec8aa669 667 /*
bc96f242
FF		 668 * Do not sample if the probability is already higher than 95%
669 * to avoid wasting airtime.
ec8aa669 670 */
bc96f242 671 if (mr->probability > MINSTREL_FRAC(95, 100))
8d5eab5a 672 return -1;
ec8aa669
FF		 673
674 /*
675 * Make sure that lower rates get sampled only occasionally,
676 * if the link is working perfectly.
677 */
965237ab
FF		 678 sample_dur = minstrel_get_duration(sample_idx);
679 if (sample_dur >= minstrel_get_duration(mi->max_tp_rate2) &&
680 (mi->max_prob_streams <
681 minstrel_mcs_groups[sample_group].streams ||
682 sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
c7317e41 683 if (mr->sample_skipped < 20)
8d5eab5a 684 return -1;
ec8aa669
FF		 685
686 if (mi->sample_slow++ > 2)
8d5eab5a 687 return -1;
ec8aa669 688 }
098b8afb 689 mi->sample_tries--;
ec8aa669
FF		 690
691 return sample_idx;
ec8aa669
FF		 692}
693
a0497f9f
FF		 694static void
695minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
696 struct minstrel_ht_sta *mi, bool val)
697{
698 u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
699
700 if (!supported || !mi->cck_supported_short)
701 return;
702
703 if (supported & (mi->cck_supported_short << (val * 4)))
704 return;
705
706 supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
707 mi->groups[MINSTREL_CCK_GROUP].supported = supported;
708}
709
ec8aa669
FF		 710static void
711minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
712 struct ieee80211_tx_rate_control *txrc)
713{
714 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
715 struct ieee80211_tx_rate *ar = info->status.rates;
716 struct minstrel_ht_sta_priv *msp = priv_sta;
717 struct minstrel_ht_sta *mi = &msp->ht;
718 struct minstrel_priv *mp = priv;
719 int sample_idx;
c7317e41 720 bool sample = false;
ec8aa669
FF		 721
722 if (rate_control_send_low(sta, priv_sta, txrc))
723 return;
724
725 if (!msp->is_ht)
726 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
727
728 info->flags |= mi->tx_flags;
a0497f9f 729 minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
6de062ce
HS		 730
731 /* Don't use EAPOL frames for sampling on non-mrr hw */
732 if (mp->hw->max_rates == 1 &&
733 txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
734 sample_idx = -1;
735 else
736 sample_idx = minstrel_get_sample_rate(mp, mi);
24f7580e
ZK		 737
738#ifdef CONFIG_MAC80211_DEBUGFS
739 /* use fixed index if set */
2a9e6c58
SRR		 740 if (mp->fixed_rate_idx != -1) {
741 mi->max_tp_rate = mp->fixed_rate_idx;
742 mi->max_tp_rate2 = mp->fixed_rate_idx;
743 mi->max_prob_rate = mp->fixed_rate_idx;
744 sample_idx = -1;
745 }
24f7580e
ZK		 746#endif
747
ec8aa669 748 if (sample_idx >= 0) {
c7317e41 749 sample = true;
ec8aa669 750 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
6048d763 751 true, false);
ec8aa669
FF		 752 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
753 } else {
754 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
6048d763 755 false, false);
ec8aa669 756 }
ec8aa669 757
cf28d793
HS		 758 if (mp->hw->max_rates >= 3) {
759 /*
760 * At least 3 tx rates supported, use
761 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
762 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
763 */
764 if (sample_idx >= 0)
765 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
6048d763 766 false, false);
cf28d793
HS		 767 else
768 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
6048d763 769 false, true);
cf28d793
HS		 770
771 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
6048d763 772 false, !sample);
cf28d793
HS		 773
774 ar[3].count = 0;
775 ar[3].idx = -1;
776 } else if (mp->hw->max_rates == 2) {
777 /*
778 * Only 2 tx rates supported, use
779 * sample_rate -> max_prob_rate for sampling and
780 * max_tp_rate -> max_prob_rate by default.
781 */
782 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
6048d763 783 false, !sample);
cf28d793
HS		 784
785 ar[2].count = 0;
786 ar[2].idx = -1;
787 } else {
788 /* Not using MRR, only use the first rate */
789 ar[1].count = 0;
790 ar[1].idx = -1;
791 }
ec8aa669
FF		 792
793 mi->total_packets++;
794
795 /* wraparound */
796 if (mi->total_packets == ~0) {
797 mi->total_packets = 0;
798 mi->sample_packets = 0;
799 }
800}
801
a0497f9f
FF		 802static void
803minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
804 struct ieee80211_supported_band *sband,
805 struct ieee80211_sta *sta)
806{
807 int i;
808
809 if (sband->band != IEEE80211_BAND_2GHZ)
810 return;
811
812 mi->cck_supported = 0;
813 mi->cck_supported_short = 0;
814 for (i = 0; i < 4; i++) {
815 if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
816 continue;
817
818 mi->cck_supported |= BIT(i);
819 if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
820 mi->cck_supported_short |= BIT(i);
821 }
822
823 mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
824}
825
ec8aa669
FF		 826static void
827minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
64f68e5d 828 struct ieee80211_sta *sta, void *priv_sta)
ec8aa669
FF		 829{
830 struct minstrel_priv *mp = priv;
831 struct minstrel_ht_sta_priv *msp = priv_sta;
832 struct minstrel_ht_sta *mi = &msp->ht;
833 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
ec8aa669 834 u16 sta_cap = sta->ht_cap.cap;
4dc217df 835 int n_supported = 0;
ec8aa669
FF		 836 int ack_dur;
837 int stbc;
838 int i;
839
840 /* fall back to the old minstrel for legacy stations */
4dc217df
FF		 841 if (!sta->ht_cap.ht_supported)
842 goto use_legacy;
ec8aa669
FF		 843
844 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
a0497f9f 845 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
ec8aa669
FF		 846
847 msp->is_ht = true;
848 memset(mi, 0, sizeof(*mi));
849 mi->stats_update = jiffies;
850
4ee73f33
MK		 851 ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
852 mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
ec8aa669
FF		 853 mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
854
855 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
856
857 /* When using MRR, sample more on the first attempt, without delay */
858 if (mp->has_mrr) {
859 mi->sample_count = 16;
860 mi->sample_wait = 0;
861 } else {
862 mi->sample_count = 8;
863 mi->sample_wait = 8;
864 }
865 mi->sample_tries = 4;
866
867 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
868 IEEE80211_HT_CAP_RX_STBC_SHIFT;
869 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
870
871 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
872 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
873
ec8aa669 874 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
ec8aa669 875 mi->groups[i].supported = 0;
a0497f9f
FF		 876 if (i == MINSTREL_CCK_GROUP) {
877 minstrel_ht_update_cck(mp, mi, sband, sta);
878 continue;
879 }
880
ec8aa669 881 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
e1a0c6b3
JB		 882 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
883 if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
884 continue;
885 } else {
886 if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
887 continue;
888 }
ec8aa669
FF		 889 }
890
e1a0c6b3
JB		 891 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
892 sta->bandwidth < IEEE80211_STA_RX_BW_40)
ec8aa669
FF		 893 continue;
894
e9219779 895 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
af0ed69b 896 if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
e9219779
HS		 897 minstrel_mcs_groups[i].streams > 1)
898 continue;
899
ec8aa669
FF		 900 mi->groups[i].supported =
901 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
4dc217df
FF		 902
903 if (mi->groups[i].supported)
904 n_supported++;
ec8aa669 905 }
4dc217df
FF		 906
907 if (!n_supported)
908 goto use_legacy;
909
a3647362
KB		 910 /* init {mi,mi->groups[*]}->{max_tp_rate,max_tp_rate2,max_prob_rate} */
911 minstrel_ht_update_stats(mp, mi);
912
4dc217df
FF		 913 return;
914
915use_legacy:
916 msp->is_ht = false;
917 memset(&msp->legacy, 0, sizeof(msp->legacy));
918 msp->legacy.r = msp->ratelist;
919 msp->legacy.sample_table = msp->sample_table;
920 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
ec8aa669
FF		 921}
922
923static void
924minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
925 struct ieee80211_sta *sta, void *priv_sta)
926{
64f68e5d 927 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
ec8aa669
FF		 928}
929
930static void
931minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
932 struct ieee80211_sta *sta, void *priv_sta,
64f68e5d 933 u32 changed)
ec8aa669 934{
64f68e5d 935 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
ec8aa669
FF		 936}
937
938static void *
939minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
940{
941 struct ieee80211_supported_band *sband;
942 struct minstrel_ht_sta_priv *msp;
943 struct minstrel_priv *mp = priv;
944 struct ieee80211_hw *hw = mp->hw;
945 int max_rates = 0;
946 int i;
947
948 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
949 sband = hw->wiphy->bands[i];
950 if (sband && sband->n_bitrates > max_rates)
951 max_rates = sband->n_bitrates;
952 }
953
472dd35c 954 msp = kzalloc(sizeof(*msp), gfp);
ec8aa669
FF		 955 if (!msp)
956 return NULL;
957
958 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
959 if (!msp->ratelist)
960 goto error;
961
962 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
963 if (!msp->sample_table)
964 goto error1;
965
966 return msp;
967
968error1:
7e988014 969 kfree(msp->ratelist);
ec8aa669
FF		 970error:
971 kfree(msp);
972 return NULL;
973}
974
975static void
976minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
977{
978 struct minstrel_ht_sta_priv *msp = priv_sta;
979
980 kfree(msp->sample_table);
981 kfree(msp->ratelist);
982 kfree(msp);
983}
984
985static void *
986minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
987{
988 return mac80211_minstrel.alloc(hw, debugfsdir);
989}
990
991static void
992minstrel_ht_free(void *priv)
993{
994 mac80211_minstrel.free(priv);
995}
996
997static struct rate_control_ops mac80211_minstrel_ht = {
998 .name = "minstrel_ht",
999 .tx_status = minstrel_ht_tx_status,
1000 .get_rate = minstrel_ht_get_rate,
1001 .rate_init = minstrel_ht_rate_init,
1002 .rate_update = minstrel_ht_rate_update,
1003 .alloc_sta = minstrel_ht_alloc_sta,
1004 .free_sta = minstrel_ht_free_sta,
1005 .alloc = minstrel_ht_alloc,
1006 .free = minstrel_ht_free,
1007#ifdef CONFIG_MAC80211_DEBUGFS
1008 .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
1009 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
1010#endif
1011};
1012
1013
1014static void
1015init_sample_table(void)
1016{
1017 int col, i, new_idx;
1018 u8 rnd[MCS_GROUP_RATES];
1019
1020 memset(sample_table, 0xff, sizeof(sample_table));
1021 for (col = 0; col < SAMPLE_COLUMNS; col++) {
1022 for (i = 0; i < MCS_GROUP_RATES; i++) {
1023 get_random_bytes(rnd, sizeof(rnd));
1024 new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
1025
1026 while (sample_table[col][new_idx] != 0xff)
1027 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
1028
1029 sample_table[col][new_idx] = i;
1030 }
1031 }
1032}
1033
1034int __init
1035rc80211_minstrel_ht_init(void)
1036{
1037 init_sample_table();
1038 return ieee80211_rate_control_register(&mac80211_minstrel_ht);
1039}
1040
1041void
1042rc80211_minstrel_ht_exit(void)
1043{
1044 ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
1045}
Linux kernel - Deliverables
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