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Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
[linux-2.6/libata-dev.git] / net / mac80211 / rc80211_minstrel_ht.c
blob3af141c6971214e9b1bb29b2976e858d86585da6
1 /*
2 * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
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
20 #define SAMPLE_COLUMNS 10
21 #define EWMA_LEVEL 75
22
23 /* Number of bits for an average sized packet */
24 #define MCS_NBITS (AVG_PKT_SIZE << 3)
25
26 /* Number of symbols for a packet with (bps) bits per symbol */
27 #define MCS_NSYMS(bps) ((MCS_NBITS + (bps) - 1) / (bps))
28
29 /* Transmission time for a packet containing (syms) symbols */
30 #define MCS_SYMBOL_TIME(sgi, syms) \
31 (sgi ? \
32 ((syms) * 18 + 4) / 5 : /* syms * 3.6 us */ \
33 (syms) << 2 /* syms * 4 us */ \
34 )
35
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)))
38
39 /*
40 * Define group sort order: HT40 -> SGI -> #streams
41 */
42 #define GROUP_IDX(_streams, _sgi, _ht40) \
43 MINSTREL_MAX_STREAMS * 2 * _ht40 + \
44 MINSTREL_MAX_STREAMS * _sgi + \
45 _streams - 1
46
47 /* MCS rate information for an MCS group */
48 #define MCS_GROUP(_streams, _sgi, _ht40) \
49 [GROUP_IDX(_streams, _sgi, _ht40)] = { \
50 .streams = _streams, \
51 .flags = \
52 (_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) | \
53 (_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0), \
54 .duration = { \
55 MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26), \
56 MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52), \
57 MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78), \
58 MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104), \
59 MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156), \
60 MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208), \
61 MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234), \
62 MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260) \
63 } \
64 }
65
66 #define CCK_DURATION(_bitrate, _short, _len) \
67 (10 /* SIFS */ + \
68 (_short ? 72 + 24 : 144 + 48 ) + \
69 (8 * (_len + 4) * 10) / (_bitrate))
70
71 #define CCK_ACK_DURATION(_bitrate, _short) \
72 (CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \
73 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))
74
75 #define CCK_DURATION_LIST(_short) \
76 CCK_ACK_DURATION(10, _short), \
77 CCK_ACK_DURATION(20, _short), \
78 CCK_ACK_DURATION(55, _short), \
79 CCK_ACK_DURATION(110, _short)
80
81 #define CCK_GROUP \
82 [MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = { \
83 .streams = 0, \
84 .duration = { \
85 CCK_DURATION_LIST(false), \
86 CCK_DURATION_LIST(true) \
87 } \
88 }
89
90 /*
91 * To enable sufficiently targeted rate sampling, MCS rates are divided into
92 * groups, based on the number of streams and flags (HT40, SGI) that they
93 * use.
94 *
95 * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
96 * HT40 -> SGI -> #streams
97 */
98 const struct mcs_group minstrel_mcs_groups[] = {
99 MCS_GROUP(1, 0, 0),
100 MCS_GROUP(2, 0, 0),
101 #if MINSTREL_MAX_STREAMS >= 3
102 MCS_GROUP(3, 0, 0),
103 #endif
104
105 MCS_GROUP(1, 1, 0),
106 MCS_GROUP(2, 1, 0),
107 #if MINSTREL_MAX_STREAMS >= 3
108 MCS_GROUP(3, 1, 0),
109 #endif
110
111 MCS_GROUP(1, 0, 1),
112 MCS_GROUP(2, 0, 1),
113 #if MINSTREL_MAX_STREAMS >= 3
114 MCS_GROUP(3, 0, 1),
115 #endif
116
117 MCS_GROUP(1, 1, 1),
118 MCS_GROUP(2, 1, 1),
119 #if MINSTREL_MAX_STREAMS >= 3
120 MCS_GROUP(3, 1, 1),
121 #endif
122
123 /* must be last */
124 CCK_GROUP
125 };
126
127 #define MINSTREL_CCK_GROUP (ARRAY_SIZE(minstrel_mcs_groups) - 1)
128
129 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
130
131 /*
132 * Perform EWMA (Exponentially Weighted Moving Average) calculation
133 */
134 static int
135 minstrel_ewma(int old, int new, int weight)
136 {
137 return (new * (100 - weight) + old * weight) / 100;
138 }
139
140 /*
141 * Look up an MCS group index based on mac80211 rate information
142 */
143 static int
144 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
145 {
146 return GROUP_IDX((rate->idx / MCS_GROUP_RATES) + 1,
147 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
148 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
149 }
150
151 static struct minstrel_rate_stats *
152 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
153 struct ieee80211_tx_rate *rate)
154 {
155 int group, idx;
156
157 if (rate->flags & IEEE80211_TX_RC_MCS) {
158 group = minstrel_ht_get_group_idx(rate);
159 idx = rate->idx % MCS_GROUP_RATES;
160 } else {
161 group = MINSTREL_CCK_GROUP;
162
163 for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
164 if (rate->idx == mp->cck_rates[idx])
165 break;
166
167 /* short preamble */
168 if (!(mi->groups[group].supported & BIT(idx)))
169 idx += 4;
170 }
171 return &mi->groups[group].rates[idx];
172 }
173
174 static inline struct minstrel_rate_stats *
175 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
176 {
177 return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
178 }
179
180
181 /*
182 * Recalculate success probabilities and counters for a rate using EWMA
183 */
184 static void
185 minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
186 {
187 if (unlikely(mr->attempts > 0)) {
188 mr->sample_skipped = 0;
189 mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
190 if (!mr->att_hist)
191 mr->probability = mr->cur_prob;
192 else
193 mr->probability = minstrel_ewma(mr->probability,
194 mr->cur_prob, EWMA_LEVEL);
195 mr->att_hist += mr->attempts;
196 mr->succ_hist += mr->success;
197 } else {
198 mr->sample_skipped++;
199 }
200 mr->last_success = mr->success;
201 mr->last_attempts = mr->attempts;
202 mr->success = 0;
203 mr->attempts = 0;
204 }
205
206 /*
207 * Calculate throughput based on the average A-MPDU length, taking into account
208 * the expected number of retransmissions and their expected length
209 */
210 static void
211 minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
212 {
213 struct minstrel_rate_stats *mr;
214 unsigned int usecs = 0;
215
216 mr = &mi->groups[group].rates[rate];
217
218 if (mr->probability < MINSTREL_FRAC(1, 10)) {
219 mr->cur_tp = 0;
220 return;
221 }
222
223 if (group != MINSTREL_CCK_GROUP)
224 usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
225
226 usecs += minstrel_mcs_groups[group].duration[rate];
227 mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
228 }
229
230 /*
231 * Update rate statistics and select new primary rates
232 *
233 * Rules for rate selection:
234 * - max_prob_rate must use only one stream, as a tradeoff between delivery
235 * probability and throughput during strong fluctuations
236 * - as long as the max prob rate has a probability of more than 3/4, pick
237 * higher throughput rates, even if the probablity is a bit lower
238 */
239 static void
240 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
241 {
242 struct minstrel_mcs_group_data *mg;
243 struct minstrel_rate_stats *mr;
244 int cur_prob, cur_prob_tp, cur_tp, cur_tp2;
245 int group, i, index;
246
247 if (mi->ampdu_packets > 0) {
248 mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
249 MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
250 mi->ampdu_len = 0;
251 mi->ampdu_packets = 0;
252 }
253
254 mi->sample_slow = 0;
255 mi->sample_count = 0;
256 mi->max_tp_rate = 0;
257 mi->max_tp_rate2 = 0;
258 mi->max_prob_rate = 0;
259
260 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
261 cur_prob = 0;
262 cur_prob_tp = 0;
263 cur_tp = 0;
264 cur_tp2 = 0;
265
266 mg = &mi->groups[group];
267 if (!mg->supported)
268 continue;
269
270 mg->max_tp_rate = 0;
271 mg->max_tp_rate2 = 0;
272 mg->max_prob_rate = 0;
273 mi->sample_count++;
274
275 for (i = 0; i < MCS_GROUP_RATES; i++) {
276 if (!(mg->supported & BIT(i)))
277 continue;
278
279 mr = &mg->rates[i];
280 mr->retry_updated = false;
281 index = MCS_GROUP_RATES * group + i;
282 minstrel_calc_rate_ewma(mr);
283 minstrel_ht_calc_tp(mi, group, i);
284
285 if (!mr->cur_tp)
286 continue;
287
288 if ((mr->cur_tp > cur_prob_tp && mr->probability >
289 MINSTREL_FRAC(3, 4)) || mr->probability > cur_prob) {
290 mg->max_prob_rate = index;
291 cur_prob = mr->probability;
292 cur_prob_tp = mr->cur_tp;
293 }
294
295 if (mr->cur_tp > cur_tp) {
296 swap(index, mg->max_tp_rate);
297 cur_tp = mr->cur_tp;
298 mr = minstrel_get_ratestats(mi, index);
299 }
300
301 if (index >= mg->max_tp_rate)
302 continue;
303
304 if (mr->cur_tp > cur_tp2) {
305 mg->max_tp_rate2 = index;
306 cur_tp2 = mr->cur_tp;
307 }
308 }
309 }
310
311 /* try to sample up to half of the available rates during each interval */
312 mi->sample_count *= 4;
313
314 cur_prob = 0;
315 cur_prob_tp = 0;
316 cur_tp = 0;
317 cur_tp2 = 0;
318 for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
319 mg = &mi->groups[group];
320 if (!mg->supported)
321 continue;
322
323 mr = minstrel_get_ratestats(mi, mg->max_prob_rate);
324 if (cur_prob_tp < mr->cur_tp &&
325 minstrel_mcs_groups[group].streams == 1) {
326 mi->max_prob_rate = mg->max_prob_rate;
327 cur_prob = mr->cur_prob;
328 cur_prob_tp = mr->cur_tp;
329 }
330
331 mr = minstrel_get_ratestats(mi, mg->max_tp_rate);
332 if (cur_tp < mr->cur_tp) {
333 mi->max_tp_rate2 = mi->max_tp_rate;
334 cur_tp2 = cur_tp;
335 mi->max_tp_rate = mg->max_tp_rate;
336 cur_tp = mr->cur_tp;
337 }
338
339 mr = minstrel_get_ratestats(mi, mg->max_tp_rate2);
340 if (cur_tp2 < mr->cur_tp) {
341 mi->max_tp_rate2 = mg->max_tp_rate2;
342 cur_tp2 = mr->cur_tp;
343 }
344 }
345
346 mi->stats_update = jiffies;
347 }
348
349 static bool
350 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
351 {
352 if (rate->idx < 0)
353 return false;
354
355 if (!rate->count)
356 return false;
357
358 if (rate->flags & IEEE80211_TX_RC_MCS)
359 return true;
360
361 return rate->idx == mp->cck_rates[0] ||
362 rate->idx == mp->cck_rates[1] ||
363 rate->idx == mp->cck_rates[2] ||
364 rate->idx == mp->cck_rates[3];
365 }
366
367 static void
368 minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
369 {
370 struct minstrel_mcs_group_data *mg;
371
372 for (;;) {
373 mi->sample_group++;
374 mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
375 mg = &mi->groups[mi->sample_group];
376
377 if (!mg->supported)
378 continue;
379
380 if (++mg->index >= MCS_GROUP_RATES) {
381 mg->index = 0;
382 if (++mg->column >= ARRAY_SIZE(sample_table))
383 mg->column = 0;
384 }
385 break;
386 }
387 }
388
389 static void
390 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, unsigned int *idx,
391 bool primary)
392 {
393 int group, orig_group;
394
395 orig_group = group = *idx / MCS_GROUP_RATES;
396 while (group > 0) {
397 group--;
398
399 if (!mi->groups[group].supported)
400 continue;
401
402 if (minstrel_mcs_groups[group].streams >
403 minstrel_mcs_groups[orig_group].streams)
404 continue;
405
406 if (primary)
407 *idx = mi->groups[group].max_tp_rate;
408 else
409 *idx = mi->groups[group].max_tp_rate2;
410 break;
411 }
412 }
413
414 static void
415 minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
416 {
417 struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
418 struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
419 u16 tid;
420
421 if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
422 return;
423
424 if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
425 return;
426
427 tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
428 if (likely(sta->ampdu_mlme.tid_tx[tid]))
429 return;
430
431 if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
432 return;
433
434 ieee80211_start_tx_ba_session(pubsta, tid, 5000);
435 }
436
437 static void
438 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
439 struct ieee80211_sta *sta, void *priv_sta,
440 struct sk_buff *skb)
441 {
442 struct minstrel_ht_sta_priv *msp = priv_sta;
443 struct minstrel_ht_sta *mi = &msp->ht;
444 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
445 struct ieee80211_tx_rate *ar = info->status.rates;
446 struct minstrel_rate_stats *rate, *rate2;
447 struct minstrel_priv *mp = priv;
448 bool last;
449 int i;
450
451 if (!msp->is_ht)
452 return mac80211_minstrel.tx_status(priv, sband, sta, &msp->legacy, skb);
453
454 /* This packet was aggregated but doesn't carry status info */
455 if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
456 !(info->flags & IEEE80211_TX_STAT_AMPDU))
457 return;
458
459 if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
460 info->status.ampdu_ack_len =
461 (info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
462 info->status.ampdu_len = 1;
463 }
464
465 mi->ampdu_packets++;
466 mi->ampdu_len += info->status.ampdu_len;
467
468 if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
469 mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
470 mi->sample_tries = 2;
471 mi->sample_count--;
472 }
473
474 if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
475 mi->sample_packets += info->status.ampdu_len;
476
477 last = !minstrel_ht_txstat_valid(mp, &ar[0]);
478 for (i = 0; !last; i++) {
479 last = (i == IEEE80211_TX_MAX_RATES - 1) ||
480 !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
481
482 rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
483
484 if (last)
485 rate->success += info->status.ampdu_ack_len;
486
487 rate->attempts += ar[i].count * info->status.ampdu_len;
488 }
489
490 /*
491 * check for sudden death of spatial multiplexing,
492 * downgrade to a lower number of streams if necessary.
493 */
494 rate = minstrel_get_ratestats(mi, mi->max_tp_rate);
495 if (rate->attempts > 30 &&
496 MINSTREL_FRAC(rate->success, rate->attempts) <
497 MINSTREL_FRAC(20, 100))
498 minstrel_downgrade_rate(mi, &mi->max_tp_rate, true);
499
500 rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate2);
501 if (rate2->attempts > 30 &&
502 MINSTREL_FRAC(rate2->success, rate2->attempts) <
503 MINSTREL_FRAC(20, 100))
504 minstrel_downgrade_rate(mi, &mi->max_tp_rate2, false);
505
506 if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
507 minstrel_ht_update_stats(mp, mi);
508 if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
509 mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
510 minstrel_aggr_check(sta, skb);
511 }
512 }
513
514 static void
515 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
516 int index)
517 {
518 struct minstrel_rate_stats *mr;
519 const struct mcs_group *group;
520 unsigned int tx_time, tx_time_rtscts, tx_time_data;
521 unsigned int cw = mp->cw_min;
522 unsigned int ctime = 0;
523 unsigned int t_slot = 9; /* FIXME */
524 unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
525 unsigned int overhead = 0, overhead_rtscts = 0;
526
527 mr = minstrel_get_ratestats(mi, index);
528 if (mr->probability < MINSTREL_FRAC(1, 10)) {
529 mr->retry_count = 1;
530 mr->retry_count_rtscts = 1;
531 return;
532 }
533
534 mr->retry_count = 2;
535 mr->retry_count_rtscts = 2;
536 mr->retry_updated = true;
537
538 group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
539 tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len;
540
541 /* Contention time for first 2 tries */
542 ctime = (t_slot * cw) >> 1;
543 cw = min((cw << 1) | 1, mp->cw_max);
544 ctime += (t_slot * cw) >> 1;
545 cw = min((cw << 1) | 1, mp->cw_max);
546
547 if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
548 overhead = mi->overhead;
549 overhead_rtscts = mi->overhead_rtscts;
550 }
551
552 /* Total TX time for data and Contention after first 2 tries */
553 tx_time = ctime + 2 * (overhead + tx_time_data);
554 tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
555
556 /* See how many more tries we can fit inside segment size */
557 do {
558 /* Contention time for this try */
559 ctime = (t_slot * cw) >> 1;
560 cw = min((cw << 1) | 1, mp->cw_max);
561
562 /* Total TX time after this try */
563 tx_time += ctime + overhead + tx_time_data;
564 tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
565
566 if (tx_time_rtscts < mp->segment_size)
567 mr->retry_count_rtscts++;
568 } while ((tx_time < mp->segment_size) &&
569 (++mr->retry_count < mp->max_retry));
570 }
571
572
573 static void
574 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
575 struct ieee80211_tx_rate *rate, int index,
576 bool sample, bool rtscts)
577 {
578 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
579 struct minstrel_rate_stats *mr;
580
581 mr = minstrel_get_ratestats(mi, index);
582 if (!mr->retry_updated)
583 minstrel_calc_retransmit(mp, mi, index);
584
585 if (sample)
586 rate->count = 1;
587 else if (mr->probability < MINSTREL_FRAC(20, 100))
588 rate->count = 2;
589 else if (rtscts)
590 rate->count = mr->retry_count_rtscts;
591 else
592 rate->count = mr->retry_count;
593
594 rate->flags = 0;
595 if (rtscts)
596 rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
597
598 if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
599 rate->idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
600 return;
601 }
602
603 rate->flags |= IEEE80211_TX_RC_MCS | group->flags;
604 rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
605 }
606
607 static inline int
608 minstrel_get_duration(int index)
609 {
610 const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
611 return group->duration[index % MCS_GROUP_RATES];
612 }
613
614 static int
615 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
616 {
617 struct minstrel_rate_stats *mr;
618 struct minstrel_mcs_group_data *mg;
619 int sample_idx = 0;
620
621 if (mi->sample_wait > 0) {
622 mi->sample_wait--;
623 return -1;
624 }
625
626 if (!mi->sample_tries)
627 return -1;
628
629 mi->sample_tries--;
630 mg = &mi->groups[mi->sample_group];
631 sample_idx = sample_table[mg->column][mg->index];
632 mr = &mg->rates[sample_idx];
633 sample_idx += mi->sample_group * MCS_GROUP_RATES;
634 minstrel_next_sample_idx(mi);
635
636 /*
637 * Sampling might add some overhead (RTS, no aggregation)
638 * to the frame. Hence, don't use sampling for the currently
639 * used max TP rate.
640 */
641 if (sample_idx == mi->max_tp_rate)
642 return -1;
643 /*
644 * When not using MRR, do not sample if the probability is already
645 * higher than 95% to avoid wasting airtime
646 */
647 if (!mp->has_mrr && (mr->probability > MINSTREL_FRAC(95, 100)))
648 return -1;
649
650 /*
651 * Make sure that lower rates get sampled only occasionally,
652 * if the link is working perfectly.
653 */
654 if (minstrel_get_duration(sample_idx) >
655 minstrel_get_duration(mi->max_tp_rate)) {
656 if (mr->sample_skipped < 20)
657 return -1;
658
659 if (mi->sample_slow++ > 2)
660 return -1;
661 }
662
663 return sample_idx;
664 }
665
666 static void
667 minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
668 struct minstrel_ht_sta *mi, bool val)
669 {
670 u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
671
672 if (!supported || !mi->cck_supported_short)
673 return;
674
675 if (supported & (mi->cck_supported_short << (val * 4)))
676 return;
677
678 supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
679 mi->groups[MINSTREL_CCK_GROUP].supported = supported;
680 }
681
682 static void
683 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
684 struct ieee80211_tx_rate_control *txrc)
685 {
686 struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
687 struct ieee80211_tx_rate *ar = info->status.rates;
688 struct minstrel_ht_sta_priv *msp = priv_sta;
689 struct minstrel_ht_sta *mi = &msp->ht;
690 struct minstrel_priv *mp = priv;
691 int sample_idx;
692 bool sample = false;
693
694 if (rate_control_send_low(sta, priv_sta, txrc))
695 return;
696
697 if (!msp->is_ht)
698 return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
699
700 info->flags |= mi->tx_flags;
701 minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
702
703 /* Don't use EAPOL frames for sampling on non-mrr hw */
704 if (mp->hw->max_rates == 1 &&
705 txrc->skb->protocol == cpu_to_be16(ETH_P_PAE))
706 sample_idx = -1;
707 else
708 sample_idx = minstrel_get_sample_rate(mp, mi);
709
710 #ifdef CONFIG_MAC80211_DEBUGFS
711 /* use fixed index if set */
712 if (mp->fixed_rate_idx != -1) {
713 mi->max_tp_rate = mp->fixed_rate_idx;
714 mi->max_tp_rate2 = mp->fixed_rate_idx;
715 mi->max_prob_rate = mp->fixed_rate_idx;
716 sample_idx = -1;
717 }
718 #endif
719
720 if (sample_idx >= 0) {
721 sample = true;
722 minstrel_ht_set_rate(mp, mi, &ar[0], sample_idx,
723 true, false);
724 info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
725 } else {
726 minstrel_ht_set_rate(mp, mi, &ar[0], mi->max_tp_rate,
727 false, false);
728 }
729
730 if (mp->hw->max_rates >= 3) {
731 /*
732 * At least 3 tx rates supported, use
733 * sample_rate -> max_tp_rate -> max_prob_rate for sampling and
734 * max_tp_rate -> max_tp_rate2 -> max_prob_rate by default.
735 */
736 if (sample_idx >= 0)
737 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate,
738 false, false);
739 else
740 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_tp_rate2,
741 false, true);
742
743 minstrel_ht_set_rate(mp, mi, &ar[2], mi->max_prob_rate,
744 false, !sample);
745
746 ar[3].count = 0;
747 ar[3].idx = -1;
748 } else if (mp->hw->max_rates == 2) {
749 /*
750 * Only 2 tx rates supported, use
751 * sample_rate -> max_prob_rate for sampling and
752 * max_tp_rate -> max_prob_rate by default.
753 */
754 minstrel_ht_set_rate(mp, mi, &ar[1], mi->max_prob_rate,
755 false, !sample);
756
757 ar[2].count = 0;
758 ar[2].idx = -1;
759 } else {
760 /* Not using MRR, only use the first rate */
761 ar[1].count = 0;
762 ar[1].idx = -1;
763 }
764
765 mi->total_packets++;
766
767 /* wraparound */
768 if (mi->total_packets == ~0) {
769 mi->total_packets = 0;
770 mi->sample_packets = 0;
771 }
772 }
773
774 static void
775 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
776 struct ieee80211_supported_band *sband,
777 struct ieee80211_sta *sta)
778 {
779 int i;
780
781 if (sband->band != IEEE80211_BAND_2GHZ)
782 return;
783
784 mi->cck_supported = 0;
785 mi->cck_supported_short = 0;
786 for (i = 0; i < 4; i++) {
787 if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
788 continue;
789
790 mi->cck_supported |= BIT(i);
791 if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
792 mi->cck_supported_short |= BIT(i);
793 }
794
795 mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
796 }
797
798 static void
799 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
800 struct ieee80211_sta *sta, void *priv_sta)
801 {
802 struct minstrel_priv *mp = priv;
803 struct minstrel_ht_sta_priv *msp = priv_sta;
804 struct minstrel_ht_sta *mi = &msp->ht;
805 struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
806 u16 sta_cap = sta->ht_cap.cap;
807 int n_supported = 0;
808 int ack_dur;
809 int stbc;
810 int i;
811
812 /* fall back to the old minstrel for legacy stations */
813 if (!sta->ht_cap.ht_supported)
814 goto use_legacy;
815
816 BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
817 MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
818
819 msp->is_ht = true;
820 memset(mi, 0, sizeof(*mi));
821 mi->stats_update = jiffies;
822
823 ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1);
824 mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1) + ack_dur;
825 mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
826
827 mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
828
829 /* When using MRR, sample more on the first attempt, without delay */
830 if (mp->has_mrr) {
831 mi->sample_count = 16;
832 mi->sample_wait = 0;
833 } else {
834 mi->sample_count = 8;
835 mi->sample_wait = 8;
836 }
837 mi->sample_tries = 4;
838
839 stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
840 IEEE80211_HT_CAP_RX_STBC_SHIFT;
841 mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
842
843 if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
844 mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
845
846 for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
847 mi->groups[i].supported = 0;
848 if (i == MINSTREL_CCK_GROUP) {
849 minstrel_ht_update_cck(mp, mi, sband, sta);
850 continue;
851 }
852
853 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
854 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
855 if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
856 continue;
857 } else {
858 if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
859 continue;
860 }
861 }
862
863 if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
864 sta->bandwidth < IEEE80211_STA_RX_BW_40)
865 continue;
866
867 /* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
868 if (sta->smps_mode == IEEE80211_SMPS_STATIC &&
869 minstrel_mcs_groups[i].streams > 1)
870 continue;
871
872 mi->groups[i].supported =
873 mcs->rx_mask[minstrel_mcs_groups[i].streams - 1];
874
875 if (mi->groups[i].supported)
876 n_supported++;
877 }
878
879 if (!n_supported)
880 goto use_legacy;
881
882 return;
883
884 use_legacy:
885 msp->is_ht = false;
886 memset(&msp->legacy, 0, sizeof(msp->legacy));
887 msp->legacy.r = msp->ratelist;
888 msp->legacy.sample_table = msp->sample_table;
889 return mac80211_minstrel.rate_init(priv, sband, sta, &msp->legacy);
890 }
891
892 static void
893 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
894 struct ieee80211_sta *sta, void *priv_sta)
895 {
896 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
897 }
898
899 static void
900 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
901 struct ieee80211_sta *sta, void *priv_sta,
902 u32 changed)
903 {
904 minstrel_ht_update_caps(priv, sband, sta, priv_sta);
905 }
906
907 static void *
908 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
909 {
910 struct ieee80211_supported_band *sband;
911 struct minstrel_ht_sta_priv *msp;
912 struct minstrel_priv *mp = priv;
913 struct ieee80211_hw *hw = mp->hw;
914 int max_rates = 0;
915 int i;
916
917 for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
918 sband = hw->wiphy->bands[i];
919 if (sband && sband->n_bitrates > max_rates)
920 max_rates = sband->n_bitrates;
921 }
922
923 msp = kzalloc(sizeof(*msp), gfp);
924 if (!msp)
925 return NULL;
926
927 msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
928 if (!msp->ratelist)
929 goto error;
930
931 msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
932 if (!msp->sample_table)
933 goto error1;
934
935 return msp;
936
937 error1:
938 kfree(msp->ratelist);
939 error:
940 kfree(msp);
941 return NULL;
942 }
943
944 static void
945 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
946 {
947 struct minstrel_ht_sta_priv *msp = priv_sta;
948
949 kfree(msp->sample_table);
950 kfree(msp->ratelist);
951 kfree(msp);
952 }
953
954 static void *
955 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
956 {
957 return mac80211_minstrel.alloc(hw, debugfsdir);
958 }
959
960 static void
961 minstrel_ht_free(void *priv)
962 {
963 mac80211_minstrel.free(priv);
964 }
965
966 static struct rate_control_ops mac80211_minstrel_ht = {
967 .name = "minstrel_ht",
968 .tx_status = minstrel_ht_tx_status,
969 .get_rate = minstrel_ht_get_rate,
970 .rate_init = minstrel_ht_rate_init,
971 .rate_update = minstrel_ht_rate_update,
972 .alloc_sta = minstrel_ht_alloc_sta,
973 .free_sta = minstrel_ht_free_sta,
974 .alloc = minstrel_ht_alloc,
975 .free = minstrel_ht_free,
976 #ifdef CONFIG_MAC80211_DEBUGFS
977 .add_sta_debugfs = minstrel_ht_add_sta_debugfs,
978 .remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
979 #endif
980 };
981
982
983 static void
984 init_sample_table(void)
985 {
986 int col, i, new_idx;
987 u8 rnd[MCS_GROUP_RATES];
988
989 memset(sample_table, 0xff, sizeof(sample_table));
990 for (col = 0; col < SAMPLE_COLUMNS; col++) {
991 for (i = 0; i < MCS_GROUP_RATES; i++) {
992 get_random_bytes(rnd, sizeof(rnd));
993 new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
994
995 while (sample_table[col][new_idx] != 0xff)
996 new_idx = (new_idx + 1) % MCS_GROUP_RATES;
997
998 sample_table[col][new_idx] = i;
999 }
1000 }
1001 }
1002
1003 int __init
1004 rc80211_minstrel_ht_init(void)
1005 {
1006 init_sample_table();
1007 return ieee80211_rate_control_register(&mac80211_minstrel_ht);
1008 }
1009
1010 void
1011 rc80211_minstrel_ht_exit(void)
1012 {
1013 ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
1014 }
Linux 2.6 libata-dev (mirror)