xref: /linux/net/mac80211/rc80211_minstrel_ht.c (revision 4949009eb8d40a441dcddcd96e101e77d31cf1b2)
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/moduleparam.h>
14 #include <linux/ieee80211.h>
15 #include <net/mac80211.h>
16 #include "rate.h"
17 #include "rc80211_minstrel.h"
18 #include "rc80211_minstrel_ht.h"
19 
20 #define AVG_PKT_SIZE	1200
21 
22 /* Number of bits for an average sized packet */
23 #define MCS_NBITS (AVG_PKT_SIZE << 3)
24 
25 /* Number of symbols for a packet with (bps) bits per symbol */
26 #define MCS_NSYMS(bps) DIV_ROUND_UP(MCS_NBITS, (bps))
27 
28 /* Transmission time (nanoseconds) for a packet containing (syms) symbols */
29 #define MCS_SYMBOL_TIME(sgi, syms)					\
30 	(sgi ?								\
31 	  ((syms) * 18000 + 4000) / 5 :	/* syms * 3.6 us */		\
32 	  ((syms) * 1000) << 2		/* syms * 4 us */		\
33 	)
34 
35 /* Transmit duration for the raw data part of an average sized packet */
36 #define MCS_DURATION(streams, sgi, bps) MCS_SYMBOL_TIME(sgi, MCS_NSYMS((streams) * (bps)))
37 
38 #define BW_20			0
39 #define BW_40			1
40 #define BW_80			2
41 
42 /*
43  * Define group sort order: HT40 -> SGI -> #streams
44  */
45 #define GROUP_IDX(_streams, _sgi, _ht40)	\
46 	MINSTREL_HT_GROUP_0 +			\
47 	MINSTREL_MAX_STREAMS * 2 * _ht40 +	\
48 	MINSTREL_MAX_STREAMS * _sgi +	\
49 	_streams - 1
50 
51 /* MCS rate information for an MCS group */
52 #define MCS_GROUP(_streams, _sgi, _ht40)				\
53 	[GROUP_IDX(_streams, _sgi, _ht40)] = {				\
54 	.streams = _streams,						\
55 	.flags =							\
56 		IEEE80211_TX_RC_MCS |					\
57 		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
58 		(_ht40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),		\
59 	.duration = {							\
60 		MCS_DURATION(_streams, _sgi, _ht40 ? 54 : 26),		\
61 		MCS_DURATION(_streams, _sgi, _ht40 ? 108 : 52),		\
62 		MCS_DURATION(_streams, _sgi, _ht40 ? 162 : 78),		\
63 		MCS_DURATION(_streams, _sgi, _ht40 ? 216 : 104),	\
64 		MCS_DURATION(_streams, _sgi, _ht40 ? 324 : 156),	\
65 		MCS_DURATION(_streams, _sgi, _ht40 ? 432 : 208),	\
66 		MCS_DURATION(_streams, _sgi, _ht40 ? 486 : 234),	\
67 		MCS_DURATION(_streams, _sgi, _ht40 ? 540 : 260)		\
68 	}								\
69 }
70 
71 #define VHT_GROUP_IDX(_streams, _sgi, _bw)				\
72 	(MINSTREL_VHT_GROUP_0 +						\
73 	 MINSTREL_MAX_STREAMS * 2 * (_bw) +				\
74 	 MINSTREL_MAX_STREAMS * (_sgi) +				\
75 	 (_streams) - 1)
76 
77 #define BW2VBPS(_bw, r3, r2, r1)					\
78 	(_bw == BW_80 ? r3 : _bw == BW_40 ? r2 : r1)
79 
80 #define VHT_GROUP(_streams, _sgi, _bw)					\
81 	[VHT_GROUP_IDX(_streams, _sgi, _bw)] = {			\
82 	.streams = _streams,						\
83 	.flags =							\
84 		IEEE80211_TX_RC_VHT_MCS |				\
85 		(_sgi ? IEEE80211_TX_RC_SHORT_GI : 0) |			\
86 		(_bw == BW_80 ? IEEE80211_TX_RC_80_MHZ_WIDTH :		\
87 		 _bw == BW_40 ? IEEE80211_TX_RC_40_MHZ_WIDTH : 0),	\
88 	.duration = {							\
89 		MCS_DURATION(_streams, _sgi,				\
90 			     BW2VBPS(_bw,  117,  54,  26)),		\
91 		MCS_DURATION(_streams, _sgi,				\
92 			     BW2VBPS(_bw,  234, 108,  52)),		\
93 		MCS_DURATION(_streams, _sgi,				\
94 			     BW2VBPS(_bw,  351, 162,  78)),		\
95 		MCS_DURATION(_streams, _sgi,				\
96 			     BW2VBPS(_bw,  468, 216, 104)),		\
97 		MCS_DURATION(_streams, _sgi,				\
98 			     BW2VBPS(_bw,  702, 324, 156)),		\
99 		MCS_DURATION(_streams, _sgi,				\
100 			     BW2VBPS(_bw,  936, 432, 208)),		\
101 		MCS_DURATION(_streams, _sgi,				\
102 			     BW2VBPS(_bw, 1053, 486, 234)),		\
103 		MCS_DURATION(_streams, _sgi,				\
104 			     BW2VBPS(_bw, 1170, 540, 260)),		\
105 		MCS_DURATION(_streams, _sgi,				\
106 			     BW2VBPS(_bw, 1404, 648, 312)),		\
107 		MCS_DURATION(_streams, _sgi,				\
108 			     BW2VBPS(_bw, 1560, 720, 346))		\
109 	}								\
110 }
111 
112 #define CCK_DURATION(_bitrate, _short, _len)		\
113 	(1000 * (10 /* SIFS */ +			\
114 	 (_short ? 72 + 24 : 144 + 48) +		\
115 	 (8 * (_len + 4) * 10) / (_bitrate)))
116 
117 #define CCK_ACK_DURATION(_bitrate, _short)			\
118 	(CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) +	\
119 	 CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))
120 
121 #define CCK_DURATION_LIST(_short)			\
122 	CCK_ACK_DURATION(10, _short),			\
123 	CCK_ACK_DURATION(20, _short),			\
124 	CCK_ACK_DURATION(55, _short),			\
125 	CCK_ACK_DURATION(110, _short)
126 
127 #define CCK_GROUP					\
128 	[MINSTREL_CCK_GROUP] = {			\
129 		.streams = 0,				\
130 		.flags = 0,				\
131 		.duration = {				\
132 			CCK_DURATION_LIST(false),	\
133 			CCK_DURATION_LIST(true)		\
134 		}					\
135 	}
136 
137 #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
138 static bool minstrel_vht_only = true;
139 module_param(minstrel_vht_only, bool, 0644);
140 MODULE_PARM_DESC(minstrel_vht_only,
141 		 "Use only VHT rates when VHT is supported by sta.");
142 #endif
143 
144 /*
145  * To enable sufficiently targeted rate sampling, MCS rates are divided into
146  * groups, based on the number of streams and flags (HT40, SGI) that they
147  * use.
148  *
149  * Sortorder has to be fixed for GROUP_IDX macro to be applicable:
150  * BW -> SGI -> #streams
151  */
152 const struct mcs_group minstrel_mcs_groups[] = {
153 	MCS_GROUP(1, 0, BW_20),
154 	MCS_GROUP(2, 0, BW_20),
155 #if MINSTREL_MAX_STREAMS >= 3
156 	MCS_GROUP(3, 0, BW_20),
157 #endif
158 
159 	MCS_GROUP(1, 1, BW_20),
160 	MCS_GROUP(2, 1, BW_20),
161 #if MINSTREL_MAX_STREAMS >= 3
162 	MCS_GROUP(3, 1, BW_20),
163 #endif
164 
165 	MCS_GROUP(1, 0, BW_40),
166 	MCS_GROUP(2, 0, BW_40),
167 #if MINSTREL_MAX_STREAMS >= 3
168 	MCS_GROUP(3, 0, BW_40),
169 #endif
170 
171 	MCS_GROUP(1, 1, BW_40),
172 	MCS_GROUP(2, 1, BW_40),
173 #if MINSTREL_MAX_STREAMS >= 3
174 	MCS_GROUP(3, 1, BW_40),
175 #endif
176 
177 	CCK_GROUP,
178 
179 #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
180 	VHT_GROUP(1, 0, BW_20),
181 	VHT_GROUP(2, 0, BW_20),
182 #if MINSTREL_MAX_STREAMS >= 3
183 	VHT_GROUP(3, 0, BW_20),
184 #endif
185 
186 	VHT_GROUP(1, 1, BW_20),
187 	VHT_GROUP(2, 1, BW_20),
188 #if MINSTREL_MAX_STREAMS >= 3
189 	VHT_GROUP(3, 1, BW_20),
190 #endif
191 
192 	VHT_GROUP(1, 0, BW_40),
193 	VHT_GROUP(2, 0, BW_40),
194 #if MINSTREL_MAX_STREAMS >= 3
195 	VHT_GROUP(3, 0, BW_40),
196 #endif
197 
198 	VHT_GROUP(1, 1, BW_40),
199 	VHT_GROUP(2, 1, BW_40),
200 #if MINSTREL_MAX_STREAMS >= 3
201 	VHT_GROUP(3, 1, BW_40),
202 #endif
203 
204 	VHT_GROUP(1, 0, BW_80),
205 	VHT_GROUP(2, 0, BW_80),
206 #if MINSTREL_MAX_STREAMS >= 3
207 	VHT_GROUP(3, 0, BW_80),
208 #endif
209 
210 	VHT_GROUP(1, 1, BW_80),
211 	VHT_GROUP(2, 1, BW_80),
212 #if MINSTREL_MAX_STREAMS >= 3
213 	VHT_GROUP(3, 1, BW_80),
214 #endif
215 #endif
216 };
217 
218 static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES] __read_mostly;
219 
220 static void
221 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi);
222 
223 /*
224  * Some VHT MCSes are invalid (when Ndbps / Nes is not an integer)
225  * e.g for MCS9@20MHzx1Nss: Ndbps=8x52*(5/6) Nes=1
226  *
227  * Returns the valid mcs map for struct minstrel_mcs_group_data.supported
228  */
229 static u16
230 minstrel_get_valid_vht_rates(int bw, int nss, __le16 mcs_map)
231 {
232 	u16 mask = 0;
233 
234 	if (bw == BW_20) {
235 		if (nss != 3 && nss != 6)
236 			mask = BIT(9);
237 	} else if (bw == BW_80) {
238 		if (nss == 3 || nss == 7)
239 			mask = BIT(6);
240 		else if (nss == 6)
241 			mask = BIT(9);
242 	} else {
243 		WARN_ON(bw != BW_40);
244 	}
245 
246 	switch ((le16_to_cpu(mcs_map) >> (2 * (nss - 1))) & 3) {
247 	case IEEE80211_VHT_MCS_SUPPORT_0_7:
248 		mask |= 0x300;
249 		break;
250 	case IEEE80211_VHT_MCS_SUPPORT_0_8:
251 		mask |= 0x200;
252 		break;
253 	case IEEE80211_VHT_MCS_SUPPORT_0_9:
254 		break;
255 	default:
256 		mask = 0x3ff;
257 	}
258 
259 	return 0x3ff & ~mask;
260 }
261 
262 /*
263  * Look up an MCS group index based on mac80211 rate information
264  */
265 static int
266 minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
267 {
268 	return GROUP_IDX((rate->idx / 8) + 1,
269 			 !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
270 			 !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
271 }
272 
273 static int
274 minstrel_vht_get_group_idx(struct ieee80211_tx_rate *rate)
275 {
276 	return VHT_GROUP_IDX(ieee80211_rate_get_vht_nss(rate),
277 			     !!(rate->flags & IEEE80211_TX_RC_SHORT_GI),
278 			     !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH) +
279 			     2*!!(rate->flags & IEEE80211_TX_RC_80_MHZ_WIDTH));
280 }
281 
282 static struct minstrel_rate_stats *
283 minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
284 		      struct ieee80211_tx_rate *rate)
285 {
286 	int group, idx;
287 
288 	if (rate->flags & IEEE80211_TX_RC_MCS) {
289 		group = minstrel_ht_get_group_idx(rate);
290 		idx = rate->idx % 8;
291 	} else if (rate->flags & IEEE80211_TX_RC_VHT_MCS) {
292 		group = minstrel_vht_get_group_idx(rate);
293 		idx = ieee80211_rate_get_vht_mcs(rate);
294 	} else {
295 		group = MINSTREL_CCK_GROUP;
296 
297 		for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
298 			if (rate->idx == mp->cck_rates[idx])
299 				break;
300 
301 		/* short preamble */
302 		if (!(mi->groups[group].supported & BIT(idx)))
303 			idx += 4;
304 	}
305 	return &mi->groups[group].rates[idx];
306 }
307 
308 static inline struct minstrel_rate_stats *
309 minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
310 {
311 	return &mi->groups[index / MCS_GROUP_RATES].rates[index % MCS_GROUP_RATES];
312 }
313 
314 
315 /*
316  * Recalculate success probabilities and counters for a rate using EWMA
317  */
318 static void
319 minstrel_calc_rate_ewma(struct minstrel_rate_stats *mr)
320 {
321 	if (unlikely(mr->attempts > 0)) {
322 		mr->sample_skipped = 0;
323 		mr->cur_prob = MINSTREL_FRAC(mr->success, mr->attempts);
324 		if (!mr->att_hist)
325 			mr->probability = mr->cur_prob;
326 		else
327 			mr->probability = minstrel_ewma(mr->probability,
328 				mr->cur_prob, EWMA_LEVEL);
329 		mr->att_hist += mr->attempts;
330 		mr->succ_hist += mr->success;
331 	} else {
332 		mr->sample_skipped++;
333 	}
334 	mr->last_success = mr->success;
335 	mr->last_attempts = mr->attempts;
336 	mr->success = 0;
337 	mr->attempts = 0;
338 }
339 
340 /*
341  * Calculate throughput based on the average A-MPDU length, taking into account
342  * the expected number of retransmissions and their expected length
343  */
344 static void
345 minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
346 {
347 	struct minstrel_rate_stats *mr;
348 	unsigned int nsecs = 0;
349 	unsigned int tp;
350 	unsigned int prob;
351 
352 	mr = &mi->groups[group].rates[rate];
353 	prob = mr->probability;
354 
355 	if (prob < MINSTREL_FRAC(1, 10)) {
356 		mr->cur_tp = 0;
357 		return;
358 	}
359 
360 	/*
361 	 * For the throughput calculation, limit the probability value to 90% to
362 	 * account for collision related packet error rate fluctuation
363 	 */
364 	if (prob > MINSTREL_FRAC(9, 10))
365 		prob = MINSTREL_FRAC(9, 10);
366 
367 	if (group != MINSTREL_CCK_GROUP)
368 		nsecs = 1000 * mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
369 
370 	nsecs += minstrel_mcs_groups[group].duration[rate];
371 
372 	/* prob is scaled - see MINSTREL_FRAC above */
373 	tp = 1000000 * ((prob * 1000) / nsecs);
374 	mr->cur_tp = MINSTREL_TRUNC(tp);
375 }
376 
377 /*
378  * Find & sort topmost throughput rates
379  *
380  * If multiple rates provide equal throughput the sorting is based on their
381  * current success probability. Higher success probability is preferred among
382  * MCS groups, CCK rates do not provide aggregation and are therefore at last.
383  */
384 static void
385 minstrel_ht_sort_best_tp_rates(struct minstrel_ht_sta *mi, u16 index,
386 			       u16 *tp_list)
387 {
388 	int cur_group, cur_idx, cur_thr, cur_prob;
389 	int tmp_group, tmp_idx, tmp_thr, tmp_prob;
390 	int j = MAX_THR_RATES;
391 
392 	cur_group = index / MCS_GROUP_RATES;
393 	cur_idx = index  % MCS_GROUP_RATES;
394 	cur_thr = mi->groups[cur_group].rates[cur_idx].cur_tp;
395 	cur_prob = mi->groups[cur_group].rates[cur_idx].probability;
396 
397 	do {
398 		tmp_group = tp_list[j - 1] / MCS_GROUP_RATES;
399 		tmp_idx = tp_list[j - 1] % MCS_GROUP_RATES;
400 		tmp_thr = mi->groups[tmp_group].rates[tmp_idx].cur_tp;
401 		tmp_prob = mi->groups[tmp_group].rates[tmp_idx].probability;
402 		if (cur_thr < tmp_thr ||
403 		    (cur_thr == tmp_thr && cur_prob <= tmp_prob))
404 			break;
405 		j--;
406 	} while (j > 0);
407 
408 	if (j < MAX_THR_RATES - 1) {
409 		memmove(&tp_list[j + 1], &tp_list[j], (sizeof(*tp_list) *
410 		       (MAX_THR_RATES - (j + 1))));
411 	}
412 	if (j < MAX_THR_RATES)
413 		tp_list[j] = index;
414 }
415 
416 /*
417  * Find and set the topmost probability rate per sta and per group
418  */
419 static void
420 minstrel_ht_set_best_prob_rate(struct minstrel_ht_sta *mi, u16 index)
421 {
422 	struct minstrel_mcs_group_data *mg;
423 	struct minstrel_rate_stats *mr;
424 	int tmp_group, tmp_idx, tmp_tp, tmp_prob, max_tp_group;
425 
426 	mg = &mi->groups[index / MCS_GROUP_RATES];
427 	mr = &mg->rates[index % MCS_GROUP_RATES];
428 
429 	tmp_group = mi->max_prob_rate / MCS_GROUP_RATES;
430 	tmp_idx = mi->max_prob_rate % MCS_GROUP_RATES;
431 	tmp_tp = mi->groups[tmp_group].rates[tmp_idx].cur_tp;
432 	tmp_prob = mi->groups[tmp_group].rates[tmp_idx].probability;
433 
434 	/* if max_tp_rate[0] is from MCS_GROUP max_prob_rate get selected from
435 	 * MCS_GROUP as well as CCK_GROUP rates do not allow aggregation */
436 	max_tp_group = mi->max_tp_rate[0] / MCS_GROUP_RATES;
437 	if((index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) &&
438 	    (max_tp_group != MINSTREL_CCK_GROUP))
439 		return;
440 
441 	if (mr->probability > MINSTREL_FRAC(75, 100)) {
442 		if (mr->cur_tp > tmp_tp)
443 			mi->max_prob_rate = index;
444 		if (mr->cur_tp > mg->rates[mg->max_group_prob_rate].cur_tp)
445 			mg->max_group_prob_rate = index;
446 	} else {
447 		if (mr->probability > tmp_prob)
448 			mi->max_prob_rate = index;
449 		if (mr->probability > mg->rates[mg->max_group_prob_rate].probability)
450 			mg->max_group_prob_rate = index;
451 	}
452 }
453 
454 
455 /*
456  * Assign new rate set per sta and use CCK rates only if the fastest
457  * rate (max_tp_rate[0]) is from CCK group. This prohibits such sorted
458  * rate sets where MCS and CCK rates are mixed, because CCK rates can
459  * not use aggregation.
460  */
461 static void
462 minstrel_ht_assign_best_tp_rates(struct minstrel_ht_sta *mi,
463 				 u16 tmp_mcs_tp_rate[MAX_THR_RATES],
464 				 u16 tmp_cck_tp_rate[MAX_THR_RATES])
465 {
466 	unsigned int tmp_group, tmp_idx, tmp_cck_tp, tmp_mcs_tp;
467 	int i;
468 
469 	tmp_group = tmp_cck_tp_rate[0] / MCS_GROUP_RATES;
470 	tmp_idx = tmp_cck_tp_rate[0] % MCS_GROUP_RATES;
471 	tmp_cck_tp = mi->groups[tmp_group].rates[tmp_idx].cur_tp;
472 
473 	tmp_group = tmp_mcs_tp_rate[0] / MCS_GROUP_RATES;
474 	tmp_idx = tmp_mcs_tp_rate[0] % MCS_GROUP_RATES;
475 	tmp_mcs_tp = mi->groups[tmp_group].rates[tmp_idx].cur_tp;
476 
477 	if (tmp_cck_tp > tmp_mcs_tp) {
478 		for(i = 0; i < MAX_THR_RATES; i++) {
479 			minstrel_ht_sort_best_tp_rates(mi, tmp_cck_tp_rate[i],
480 						       tmp_mcs_tp_rate);
481 		}
482 	}
483 
484 }
485 
486 /*
487  * Try to increase robustness of max_prob rate by decrease number of
488  * streams if possible.
489  */
490 static inline void
491 minstrel_ht_prob_rate_reduce_streams(struct minstrel_ht_sta *mi)
492 {
493 	struct minstrel_mcs_group_data *mg;
494 	struct minstrel_rate_stats *mr;
495 	int tmp_max_streams, group;
496 	int tmp_tp = 0;
497 
498 	tmp_max_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
499 			  MCS_GROUP_RATES].streams;
500 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
501 		mg = &mi->groups[group];
502 		if (!mg->supported || group == MINSTREL_CCK_GROUP)
503 			continue;
504 		mr = minstrel_get_ratestats(mi, mg->max_group_prob_rate);
505 		if (tmp_tp < mr->cur_tp &&
506 		   (minstrel_mcs_groups[group].streams < tmp_max_streams)) {
507 				mi->max_prob_rate = mg->max_group_prob_rate;
508 				tmp_tp = mr->cur_tp;
509 		}
510 	}
511 }
512 
513 /*
514  * Update rate statistics and select new primary rates
515  *
516  * Rules for rate selection:
517  *  - max_prob_rate must use only one stream, as a tradeoff between delivery
518  *    probability and throughput during strong fluctuations
519  *  - as long as the max prob rate has a probability of more than 75%, pick
520  *    higher throughput rates, even if the probablity is a bit lower
521  */
522 static void
523 minstrel_ht_update_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
524 {
525 	struct minstrel_mcs_group_data *mg;
526 	struct minstrel_rate_stats *mr;
527 	int group, i, j;
528 	u16 tmp_mcs_tp_rate[MAX_THR_RATES], tmp_group_tp_rate[MAX_THR_RATES];
529 	u16 tmp_cck_tp_rate[MAX_THR_RATES], index;
530 
531 	if (mi->ampdu_packets > 0) {
532 		mi->avg_ampdu_len = minstrel_ewma(mi->avg_ampdu_len,
533 			MINSTREL_FRAC(mi->ampdu_len, mi->ampdu_packets), EWMA_LEVEL);
534 		mi->ampdu_len = 0;
535 		mi->ampdu_packets = 0;
536 	}
537 
538 	mi->sample_slow = 0;
539 	mi->sample_count = 0;
540 
541 	/* Initialize global rate indexes */
542 	for(j = 0; j < MAX_THR_RATES; j++){
543 		tmp_mcs_tp_rate[j] = 0;
544 		tmp_cck_tp_rate[j] = 0;
545 	}
546 
547 	/* Find best rate sets within all MCS groups*/
548 	for (group = 0; group < ARRAY_SIZE(minstrel_mcs_groups); group++) {
549 
550 		mg = &mi->groups[group];
551 		if (!mg->supported)
552 			continue;
553 
554 		mi->sample_count++;
555 
556 		/* (re)Initialize group rate indexes */
557 		for(j = 0; j < MAX_THR_RATES; j++)
558 			tmp_group_tp_rate[j] = group;
559 
560 		for (i = 0; i < MCS_GROUP_RATES; i++) {
561 			if (!(mg->supported & BIT(i)))
562 				continue;
563 
564 			index = MCS_GROUP_RATES * group + i;
565 
566 			mr = &mg->rates[i];
567 			mr->retry_updated = false;
568 			minstrel_calc_rate_ewma(mr);
569 			minstrel_ht_calc_tp(mi, group, i);
570 
571 			if (!mr->cur_tp)
572 				continue;
573 
574 			/* Find max throughput rate set */
575 			if (group != MINSTREL_CCK_GROUP) {
576 				minstrel_ht_sort_best_tp_rates(mi, index,
577 							       tmp_mcs_tp_rate);
578 			} else if (group == MINSTREL_CCK_GROUP) {
579 				minstrel_ht_sort_best_tp_rates(mi, index,
580 							       tmp_cck_tp_rate);
581 			}
582 
583 			/* Find max throughput rate set within a group */
584 			minstrel_ht_sort_best_tp_rates(mi, index,
585 						       tmp_group_tp_rate);
586 
587 			/* Find max probability rate per group and global */
588 			minstrel_ht_set_best_prob_rate(mi, index);
589 		}
590 
591 		memcpy(mg->max_group_tp_rate, tmp_group_tp_rate,
592 		       sizeof(mg->max_group_tp_rate));
593 	}
594 
595 	/* Assign new rate set per sta */
596 	minstrel_ht_assign_best_tp_rates(mi, tmp_mcs_tp_rate, tmp_cck_tp_rate);
597 	memcpy(mi->max_tp_rate, tmp_mcs_tp_rate, sizeof(mi->max_tp_rate));
598 
599 	/* Try to increase robustness of max_prob_rate*/
600 	minstrel_ht_prob_rate_reduce_streams(mi);
601 
602 	/* try to sample all available rates during each interval */
603 	mi->sample_count *= 8;
604 
605 #ifdef CONFIG_MAC80211_DEBUGFS
606 	/* use fixed index if set */
607 	if (mp->fixed_rate_idx != -1) {
608 		for (i = 0; i < 4; i++)
609 			mi->max_tp_rate[i] = mp->fixed_rate_idx;
610 		mi->max_prob_rate = mp->fixed_rate_idx;
611 	}
612 #endif
613 
614 	/* Reset update timer */
615 	mi->stats_update = jiffies;
616 }
617 
618 static bool
619 minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
620 {
621 	if (rate->idx < 0)
622 		return false;
623 
624 	if (!rate->count)
625 		return false;
626 
627 	if (rate->flags & IEEE80211_TX_RC_MCS ||
628 	    rate->flags & IEEE80211_TX_RC_VHT_MCS)
629 		return true;
630 
631 	return rate->idx == mp->cck_rates[0] ||
632 	       rate->idx == mp->cck_rates[1] ||
633 	       rate->idx == mp->cck_rates[2] ||
634 	       rate->idx == mp->cck_rates[3];
635 }
636 
637 static void
638 minstrel_next_sample_idx(struct minstrel_ht_sta *mi)
639 {
640 	struct minstrel_mcs_group_data *mg;
641 
642 	for (;;) {
643 		mi->sample_group++;
644 		mi->sample_group %= ARRAY_SIZE(minstrel_mcs_groups);
645 		mg = &mi->groups[mi->sample_group];
646 
647 		if (!mg->supported)
648 			continue;
649 
650 		if (++mg->index >= MCS_GROUP_RATES) {
651 			mg->index = 0;
652 			if (++mg->column >= ARRAY_SIZE(sample_table))
653 				mg->column = 0;
654 		}
655 		break;
656 	}
657 }
658 
659 static void
660 minstrel_downgrade_rate(struct minstrel_ht_sta *mi, u16 *idx, bool primary)
661 {
662 	int group, orig_group;
663 
664 	orig_group = group = *idx / MCS_GROUP_RATES;
665 	while (group > 0) {
666 		group--;
667 
668 		if (!mi->groups[group].supported)
669 			continue;
670 
671 		if (minstrel_mcs_groups[group].streams >
672 		    minstrel_mcs_groups[orig_group].streams)
673 			continue;
674 
675 		if (primary)
676 			*idx = mi->groups[group].max_group_tp_rate[0];
677 		else
678 			*idx = mi->groups[group].max_group_tp_rate[1];
679 		break;
680 	}
681 }
682 
683 static void
684 minstrel_aggr_check(struct ieee80211_sta *pubsta, struct sk_buff *skb)
685 {
686 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *) skb->data;
687 	struct sta_info *sta = container_of(pubsta, struct sta_info, sta);
688 	u16 tid;
689 
690 	if (skb_get_queue_mapping(skb) == IEEE80211_AC_VO)
691 		return;
692 
693 	if (unlikely(!ieee80211_is_data_qos(hdr->frame_control)))
694 		return;
695 
696 	if (unlikely(skb->protocol == cpu_to_be16(ETH_P_PAE)))
697 		return;
698 
699 	tid = *ieee80211_get_qos_ctl(hdr) & IEEE80211_QOS_CTL_TID_MASK;
700 	if (likely(sta->ampdu_mlme.tid_tx[tid]))
701 		return;
702 
703 	ieee80211_start_tx_ba_session(pubsta, tid, 5000);
704 }
705 
706 static void
707 minstrel_ht_tx_status(void *priv, struct ieee80211_supported_band *sband,
708                       struct ieee80211_sta *sta, void *priv_sta,
709                       struct ieee80211_tx_info *info)
710 {
711 	struct minstrel_ht_sta_priv *msp = priv_sta;
712 	struct minstrel_ht_sta *mi = &msp->ht;
713 	struct ieee80211_tx_rate *ar = info->status.rates;
714 	struct minstrel_rate_stats *rate, *rate2;
715 	struct minstrel_priv *mp = priv;
716 	bool last, update = false;
717 	int i;
718 
719 	if (!msp->is_ht)
720 		return mac80211_minstrel.tx_status_noskb(priv, sband, sta,
721 							 &msp->legacy, info);
722 
723 	/* This packet was aggregated but doesn't carry status info */
724 	if ((info->flags & IEEE80211_TX_CTL_AMPDU) &&
725 	    !(info->flags & IEEE80211_TX_STAT_AMPDU))
726 		return;
727 
728 	if (!(info->flags & IEEE80211_TX_STAT_AMPDU)) {
729 		info->status.ampdu_ack_len =
730 			(info->flags & IEEE80211_TX_STAT_ACK ? 1 : 0);
731 		info->status.ampdu_len = 1;
732 	}
733 
734 	mi->ampdu_packets++;
735 	mi->ampdu_len += info->status.ampdu_len;
736 
737 	if (!mi->sample_wait && !mi->sample_tries && mi->sample_count > 0) {
738 		mi->sample_wait = 16 + 2 * MINSTREL_TRUNC(mi->avg_ampdu_len);
739 		mi->sample_tries = 1;
740 		mi->sample_count--;
741 	}
742 
743 	if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
744 		mi->sample_packets += info->status.ampdu_len;
745 
746 	last = !minstrel_ht_txstat_valid(mp, &ar[0]);
747 	for (i = 0; !last; i++) {
748 		last = (i == IEEE80211_TX_MAX_RATES - 1) ||
749 		       !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
750 
751 		rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
752 
753 		if (last)
754 			rate->success += info->status.ampdu_ack_len;
755 
756 		rate->attempts += ar[i].count * info->status.ampdu_len;
757 	}
758 
759 	/*
760 	 * check for sudden death of spatial multiplexing,
761 	 * downgrade to a lower number of streams if necessary.
762 	 */
763 	rate = minstrel_get_ratestats(mi, mi->max_tp_rate[0]);
764 	if (rate->attempts > 30 &&
765 	    MINSTREL_FRAC(rate->success, rate->attempts) <
766 	    MINSTREL_FRAC(20, 100)) {
767 		minstrel_downgrade_rate(mi, &mi->max_tp_rate[0], true);
768 		update = true;
769 	}
770 
771 	rate2 = minstrel_get_ratestats(mi, mi->max_tp_rate[1]);
772 	if (rate2->attempts > 30 &&
773 	    MINSTREL_FRAC(rate2->success, rate2->attempts) <
774 	    MINSTREL_FRAC(20, 100)) {
775 		minstrel_downgrade_rate(mi, &mi->max_tp_rate[1], false);
776 		update = true;
777 	}
778 
779 	if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
780 		update = true;
781 		minstrel_ht_update_stats(mp, mi);
782 	}
783 
784 	if (update)
785 		minstrel_ht_update_rates(mp, mi);
786 }
787 
788 static void
789 minstrel_calc_retransmit(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
790                          int index)
791 {
792 	struct minstrel_rate_stats *mr;
793 	const struct mcs_group *group;
794 	unsigned int tx_time, tx_time_rtscts, tx_time_data;
795 	unsigned int cw = mp->cw_min;
796 	unsigned int ctime = 0;
797 	unsigned int t_slot = 9; /* FIXME */
798 	unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
799 	unsigned int overhead = 0, overhead_rtscts = 0;
800 
801 	mr = minstrel_get_ratestats(mi, index);
802 	if (mr->probability < MINSTREL_FRAC(1, 10)) {
803 		mr->retry_count = 1;
804 		mr->retry_count_rtscts = 1;
805 		return;
806 	}
807 
808 	mr->retry_count = 2;
809 	mr->retry_count_rtscts = 2;
810 	mr->retry_updated = true;
811 
812 	group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
813 	tx_time_data = group->duration[index % MCS_GROUP_RATES] * ampdu_len / 1000;
814 
815 	/* Contention time for first 2 tries */
816 	ctime = (t_slot * cw) >> 1;
817 	cw = min((cw << 1) | 1, mp->cw_max);
818 	ctime += (t_slot * cw) >> 1;
819 	cw = min((cw << 1) | 1, mp->cw_max);
820 
821 	if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
822 		overhead = mi->overhead;
823 		overhead_rtscts = mi->overhead_rtscts;
824 	}
825 
826 	/* Total TX time for data and Contention after first 2 tries */
827 	tx_time = ctime + 2 * (overhead + tx_time_data);
828 	tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
829 
830 	/* See how many more tries we can fit inside segment size */
831 	do {
832 		/* Contention time for this try */
833 		ctime = (t_slot * cw) >> 1;
834 		cw = min((cw << 1) | 1, mp->cw_max);
835 
836 		/* Total TX time after this try */
837 		tx_time += ctime + overhead + tx_time_data;
838 		tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
839 
840 		if (tx_time_rtscts < mp->segment_size)
841 			mr->retry_count_rtscts++;
842 	} while ((tx_time < mp->segment_size) &&
843 	         (++mr->retry_count < mp->max_retry));
844 }
845 
846 
847 static void
848 minstrel_ht_set_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
849                      struct ieee80211_sta_rates *ratetbl, int offset, int index)
850 {
851 	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
852 	struct minstrel_rate_stats *mr;
853 	u8 idx;
854 	u16 flags = group->flags;
855 
856 	mr = minstrel_get_ratestats(mi, index);
857 	if (!mr->retry_updated)
858 		minstrel_calc_retransmit(mp, mi, index);
859 
860 	if (mr->probability < MINSTREL_FRAC(20, 100) || !mr->retry_count) {
861 		ratetbl->rate[offset].count = 2;
862 		ratetbl->rate[offset].count_rts = 2;
863 		ratetbl->rate[offset].count_cts = 2;
864 	} else {
865 		ratetbl->rate[offset].count = mr->retry_count;
866 		ratetbl->rate[offset].count_cts = mr->retry_count;
867 		ratetbl->rate[offset].count_rts = mr->retry_count_rtscts;
868 	}
869 
870 	if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP)
871 		idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
872 	else if (flags & IEEE80211_TX_RC_VHT_MCS)
873 		idx = ((group->streams - 1) << 4) |
874 		      ((index % MCS_GROUP_RATES) & 0xF);
875 	else
876 		idx = index % MCS_GROUP_RATES + (group->streams - 1) * 8;
877 
878 	if (offset > 0) {
879 		ratetbl->rate[offset].count = ratetbl->rate[offset].count_rts;
880 		flags |= IEEE80211_TX_RC_USE_RTS_CTS;
881 	}
882 
883 	ratetbl->rate[offset].idx = idx;
884 	ratetbl->rate[offset].flags = flags;
885 }
886 
887 static void
888 minstrel_ht_update_rates(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
889 {
890 	struct ieee80211_sta_rates *rates;
891 	int i = 0;
892 
893 	rates = kzalloc(sizeof(*rates), GFP_ATOMIC);
894 	if (!rates)
895 		return;
896 
897 	/* Start with max_tp_rate[0] */
898 	minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[0]);
899 
900 	if (mp->hw->max_rates >= 3) {
901 		/* At least 3 tx rates supported, use max_tp_rate[1] next */
902 		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_tp_rate[1]);
903 	}
904 
905 	if (mp->hw->max_rates >= 2) {
906 		/*
907 		 * At least 2 tx rates supported, use max_prob_rate next */
908 		minstrel_ht_set_rate(mp, mi, rates, i++, mi->max_prob_rate);
909 	}
910 
911 	rates->rate[i].idx = -1;
912 	rate_control_set_rates(mp->hw, mi->sta, rates);
913 }
914 
915 static inline int
916 minstrel_get_duration(int index)
917 {
918 	const struct mcs_group *group = &minstrel_mcs_groups[index / MCS_GROUP_RATES];
919 	return group->duration[index % MCS_GROUP_RATES];
920 }
921 
922 static int
923 minstrel_get_sample_rate(struct minstrel_priv *mp, struct minstrel_ht_sta *mi)
924 {
925 	struct minstrel_rate_stats *mr;
926 	struct minstrel_mcs_group_data *mg;
927 	unsigned int sample_dur, sample_group, cur_max_tp_streams;
928 	int sample_idx = 0;
929 
930 	if (mi->sample_wait > 0) {
931 		mi->sample_wait--;
932 		return -1;
933 	}
934 
935 	if (!mi->sample_tries)
936 		return -1;
937 
938 	sample_group = mi->sample_group;
939 	mg = &mi->groups[sample_group];
940 	sample_idx = sample_table[mg->column][mg->index];
941 	minstrel_next_sample_idx(mi);
942 
943 	if (!(mg->supported & BIT(sample_idx)))
944 		return -1;
945 
946 	mr = &mg->rates[sample_idx];
947 	sample_idx += sample_group * MCS_GROUP_RATES;
948 
949 	/*
950 	 * Sampling might add some overhead (RTS, no aggregation)
951 	 * to the frame. Hence, don't use sampling for the currently
952 	 * used rates.
953 	 */
954 	if (sample_idx == mi->max_tp_rate[0] ||
955 	    sample_idx == mi->max_tp_rate[1] ||
956 	    sample_idx == mi->max_prob_rate)
957 		return -1;
958 
959 	/*
960 	 * Do not sample if the probability is already higher than 95%
961 	 * to avoid wasting airtime.
962 	 */
963 	if (mr->probability > MINSTREL_FRAC(95, 100))
964 		return -1;
965 
966 	/*
967 	 * Make sure that lower rates get sampled only occasionally,
968 	 * if the link is working perfectly.
969 	 */
970 
971 	cur_max_tp_streams = minstrel_mcs_groups[mi->max_tp_rate[0] /
972 		MCS_GROUP_RATES].streams;
973 	sample_dur = minstrel_get_duration(sample_idx);
974 	if (sample_dur >= minstrel_get_duration(mi->max_tp_rate[1]) &&
975 	    (cur_max_tp_streams - 1 <
976 	     minstrel_mcs_groups[sample_group].streams ||
977 	     sample_dur >= minstrel_get_duration(mi->max_prob_rate))) {
978 		if (mr->sample_skipped < 20)
979 			return -1;
980 
981 		if (mi->sample_slow++ > 2)
982 			return -1;
983 	}
984 	mi->sample_tries--;
985 
986 	return sample_idx;
987 }
988 
989 static void
990 minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
991 				    struct minstrel_ht_sta *mi, bool val)
992 {
993 	u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
994 
995 	if (!supported || !mi->cck_supported_short)
996 		return;
997 
998 	if (supported & (mi->cck_supported_short << (val * 4)))
999 		return;
1000 
1001 	supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
1002 	mi->groups[MINSTREL_CCK_GROUP].supported = supported;
1003 }
1004 
1005 static void
1006 minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
1007                      struct ieee80211_tx_rate_control *txrc)
1008 {
1009 	const struct mcs_group *sample_group;
1010 	struct ieee80211_tx_info *info = IEEE80211_SKB_CB(txrc->skb);
1011 	struct ieee80211_tx_rate *rate = &info->status.rates[0];
1012 	struct minstrel_ht_sta_priv *msp = priv_sta;
1013 	struct minstrel_ht_sta *mi = &msp->ht;
1014 	struct minstrel_priv *mp = priv;
1015 	int sample_idx;
1016 
1017 	if (rate_control_send_low(sta, priv_sta, txrc))
1018 		return;
1019 
1020 	if (!msp->is_ht)
1021 		return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
1022 
1023 	if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
1024 	    mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
1025 		minstrel_aggr_check(sta, txrc->skb);
1026 
1027 	info->flags |= mi->tx_flags;
1028 	minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
1029 
1030 #ifdef CONFIG_MAC80211_DEBUGFS
1031 	if (mp->fixed_rate_idx != -1)
1032 		return;
1033 #endif
1034 
1035 	/* Don't use EAPOL frames for sampling on non-mrr hw */
1036 	if (mp->hw->max_rates == 1 &&
1037 	    (info->control.flags & IEEE80211_TX_CTRL_PORT_CTRL_PROTO))
1038 		sample_idx = -1;
1039 	else
1040 		sample_idx = minstrel_get_sample_rate(mp, mi);
1041 
1042 	mi->total_packets++;
1043 
1044 	/* wraparound */
1045 	if (mi->total_packets == ~0) {
1046 		mi->total_packets = 0;
1047 		mi->sample_packets = 0;
1048 	}
1049 
1050 	if (sample_idx < 0)
1051 		return;
1052 
1053 	sample_group = &minstrel_mcs_groups[sample_idx / MCS_GROUP_RATES];
1054 	info->flags |= IEEE80211_TX_CTL_RATE_CTRL_PROBE;
1055 	rate->count = 1;
1056 
1057 	if (sample_idx / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
1058 		int idx = sample_idx % ARRAY_SIZE(mp->cck_rates);
1059 		rate->idx = mp->cck_rates[idx];
1060 	} else if (sample_group->flags & IEEE80211_TX_RC_VHT_MCS) {
1061 		ieee80211_rate_set_vht(rate, sample_idx % MCS_GROUP_RATES,
1062 				       sample_group->streams);
1063 	} else {
1064 		rate->idx = sample_idx % MCS_GROUP_RATES +
1065 			    (sample_group->streams - 1) * 8;
1066 	}
1067 
1068 	rate->flags = sample_group->flags;
1069 }
1070 
1071 static void
1072 minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
1073 		       struct ieee80211_supported_band *sband,
1074 		       struct ieee80211_sta *sta)
1075 {
1076 	int i;
1077 
1078 	if (sband->band != IEEE80211_BAND_2GHZ)
1079 		return;
1080 
1081 	if (!(mp->hw->flags & IEEE80211_HW_SUPPORTS_HT_CCK_RATES))
1082 		return;
1083 
1084 	mi->cck_supported = 0;
1085 	mi->cck_supported_short = 0;
1086 	for (i = 0; i < 4; i++) {
1087 		if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
1088 			continue;
1089 
1090 		mi->cck_supported |= BIT(i);
1091 		if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
1092 			mi->cck_supported_short |= BIT(i);
1093 	}
1094 
1095 	mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
1096 }
1097 
1098 static void
1099 minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
1100 			struct cfg80211_chan_def *chandef,
1101                         struct ieee80211_sta *sta, void *priv_sta)
1102 {
1103 	struct minstrel_priv *mp = priv;
1104 	struct minstrel_ht_sta_priv *msp = priv_sta;
1105 	struct minstrel_ht_sta *mi = &msp->ht;
1106 	struct ieee80211_mcs_info *mcs = &sta->ht_cap.mcs;
1107 	u16 sta_cap = sta->ht_cap.cap;
1108 	struct ieee80211_sta_vht_cap *vht_cap = &sta->vht_cap;
1109 	int use_vht;
1110 	int n_supported = 0;
1111 	int ack_dur;
1112 	int stbc;
1113 	int i;
1114 
1115 	/* fall back to the old minstrel for legacy stations */
1116 	if (!sta->ht_cap.ht_supported)
1117 		goto use_legacy;
1118 
1119 	BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) != MINSTREL_GROUPS_NB);
1120 
1121 #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
1122 	if (vht_cap->vht_supported)
1123 		use_vht = vht_cap->vht_mcs.tx_mcs_map != cpu_to_le16(~0);
1124 	else
1125 #endif
1126 	use_vht = 0;
1127 
1128 	msp->is_ht = true;
1129 	memset(mi, 0, sizeof(*mi));
1130 
1131 	mi->sta = sta;
1132 	mi->stats_update = jiffies;
1133 
1134 	ack_dur = ieee80211_frame_duration(sband->band, 10, 60, 1, 1, 0);
1135 	mi->overhead = ieee80211_frame_duration(sband->band, 0, 60, 1, 1, 0);
1136 	mi->overhead += ack_dur;
1137 	mi->overhead_rtscts = mi->overhead + 2 * ack_dur;
1138 
1139 	mi->avg_ampdu_len = MINSTREL_FRAC(1, 1);
1140 
1141 	/* When using MRR, sample more on the first attempt, without delay */
1142 	if (mp->has_mrr) {
1143 		mi->sample_count = 16;
1144 		mi->sample_wait = 0;
1145 	} else {
1146 		mi->sample_count = 8;
1147 		mi->sample_wait = 8;
1148 	}
1149 	mi->sample_tries = 4;
1150 
1151 	/* TODO tx_flags for vht - ATM the RC API is not fine-grained enough */
1152 	if (!use_vht) {
1153 		stbc = (sta_cap & IEEE80211_HT_CAP_RX_STBC) >>
1154 			IEEE80211_HT_CAP_RX_STBC_SHIFT;
1155 		mi->tx_flags |= stbc << IEEE80211_TX_CTL_STBC_SHIFT;
1156 
1157 		if (sta_cap & IEEE80211_HT_CAP_LDPC_CODING)
1158 			mi->tx_flags |= IEEE80211_TX_CTL_LDPC;
1159 	}
1160 
1161 	for (i = 0; i < ARRAY_SIZE(mi->groups); i++) {
1162 		u32 gflags = minstrel_mcs_groups[i].flags;
1163 		int bw, nss;
1164 
1165 		mi->groups[i].supported = 0;
1166 		if (i == MINSTREL_CCK_GROUP) {
1167 			minstrel_ht_update_cck(mp, mi, sband, sta);
1168 			continue;
1169 		}
1170 
1171 		if (gflags & IEEE80211_TX_RC_SHORT_GI) {
1172 			if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH) {
1173 				if (!(sta_cap & IEEE80211_HT_CAP_SGI_40))
1174 					continue;
1175 			} else {
1176 				if (!(sta_cap & IEEE80211_HT_CAP_SGI_20))
1177 					continue;
1178 			}
1179 		}
1180 
1181 		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH &&
1182 		    sta->bandwidth < IEEE80211_STA_RX_BW_40)
1183 			continue;
1184 
1185 		nss = minstrel_mcs_groups[i].streams;
1186 
1187 		/* Mark MCS > 7 as unsupported if STA is in static SMPS mode */
1188 		if (sta->smps_mode == IEEE80211_SMPS_STATIC && nss > 1)
1189 			continue;
1190 
1191 		/* HT rate */
1192 		if (gflags & IEEE80211_TX_RC_MCS) {
1193 #ifdef CONFIG_MAC80211_RC_MINSTREL_VHT
1194 			if (use_vht && minstrel_vht_only)
1195 				continue;
1196 #endif
1197 			mi->groups[i].supported = mcs->rx_mask[nss - 1];
1198 			if (mi->groups[i].supported)
1199 				n_supported++;
1200 			continue;
1201 		}
1202 
1203 		/* VHT rate */
1204 		if (!vht_cap->vht_supported ||
1205 		    WARN_ON(!(gflags & IEEE80211_TX_RC_VHT_MCS)) ||
1206 		    WARN_ON(gflags & IEEE80211_TX_RC_160_MHZ_WIDTH))
1207 			continue;
1208 
1209 		if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH) {
1210 			if (sta->bandwidth < IEEE80211_STA_RX_BW_80 ||
1211 			    ((gflags & IEEE80211_TX_RC_SHORT_GI) &&
1212 			     !(vht_cap->cap & IEEE80211_VHT_CAP_SHORT_GI_80))) {
1213 				continue;
1214 			}
1215 		}
1216 
1217 		if (gflags & IEEE80211_TX_RC_40_MHZ_WIDTH)
1218 			bw = BW_40;
1219 		else if (gflags & IEEE80211_TX_RC_80_MHZ_WIDTH)
1220 			bw = BW_80;
1221 		else
1222 			bw = BW_20;
1223 
1224 		mi->groups[i].supported = minstrel_get_valid_vht_rates(bw, nss,
1225 				vht_cap->vht_mcs.tx_mcs_map);
1226 
1227 		if (mi->groups[i].supported)
1228 			n_supported++;
1229 	}
1230 
1231 	if (!n_supported)
1232 		goto use_legacy;
1233 
1234 	/* create an initial rate table with the lowest supported rates */
1235 	minstrel_ht_update_stats(mp, mi);
1236 	minstrel_ht_update_rates(mp, mi);
1237 
1238 	return;
1239 
1240 use_legacy:
1241 	msp->is_ht = false;
1242 	memset(&msp->legacy, 0, sizeof(msp->legacy));
1243 	msp->legacy.r = msp->ratelist;
1244 	msp->legacy.sample_table = msp->sample_table;
1245 	return mac80211_minstrel.rate_init(priv, sband, chandef, sta,
1246 					   &msp->legacy);
1247 }
1248 
1249 static void
1250 minstrel_ht_rate_init(void *priv, struct ieee80211_supported_band *sband,
1251 		      struct cfg80211_chan_def *chandef,
1252                       struct ieee80211_sta *sta, void *priv_sta)
1253 {
1254 	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
1255 }
1256 
1257 static void
1258 minstrel_ht_rate_update(void *priv, struct ieee80211_supported_band *sband,
1259 			struct cfg80211_chan_def *chandef,
1260                         struct ieee80211_sta *sta, void *priv_sta,
1261                         u32 changed)
1262 {
1263 	minstrel_ht_update_caps(priv, sband, chandef, sta, priv_sta);
1264 }
1265 
1266 static void *
1267 minstrel_ht_alloc_sta(void *priv, struct ieee80211_sta *sta, gfp_t gfp)
1268 {
1269 	struct ieee80211_supported_band *sband;
1270 	struct minstrel_ht_sta_priv *msp;
1271 	struct minstrel_priv *mp = priv;
1272 	struct ieee80211_hw *hw = mp->hw;
1273 	int max_rates = 0;
1274 	int i;
1275 
1276 	for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
1277 		sband = hw->wiphy->bands[i];
1278 		if (sband && sband->n_bitrates > max_rates)
1279 			max_rates = sband->n_bitrates;
1280 	}
1281 
1282 	msp = kzalloc(sizeof(*msp), gfp);
1283 	if (!msp)
1284 		return NULL;
1285 
1286 	msp->ratelist = kzalloc(sizeof(struct minstrel_rate) * max_rates, gfp);
1287 	if (!msp->ratelist)
1288 		goto error;
1289 
1290 	msp->sample_table = kmalloc(SAMPLE_COLUMNS * max_rates, gfp);
1291 	if (!msp->sample_table)
1292 		goto error1;
1293 
1294 	return msp;
1295 
1296 error1:
1297 	kfree(msp->ratelist);
1298 error:
1299 	kfree(msp);
1300 	return NULL;
1301 }
1302 
1303 static void
1304 minstrel_ht_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
1305 {
1306 	struct minstrel_ht_sta_priv *msp = priv_sta;
1307 
1308 	kfree(msp->sample_table);
1309 	kfree(msp->ratelist);
1310 	kfree(msp);
1311 }
1312 
1313 static void *
1314 minstrel_ht_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
1315 {
1316 	return mac80211_minstrel.alloc(hw, debugfsdir);
1317 }
1318 
1319 static void
1320 minstrel_ht_free(void *priv)
1321 {
1322 	mac80211_minstrel.free(priv);
1323 }
1324 
1325 static u32 minstrel_ht_get_expected_throughput(void *priv_sta)
1326 {
1327 	struct minstrel_ht_sta_priv *msp = priv_sta;
1328 	struct minstrel_ht_sta *mi = &msp->ht;
1329 	int i, j;
1330 
1331 	if (!msp->is_ht)
1332 		return mac80211_minstrel.get_expected_throughput(priv_sta);
1333 
1334 	i = mi->max_tp_rate[0] / MCS_GROUP_RATES;
1335 	j = mi->max_tp_rate[0] % MCS_GROUP_RATES;
1336 
1337 	/* convert cur_tp from pkt per second in kbps */
1338 	return mi->groups[i].rates[j].cur_tp * AVG_PKT_SIZE * 8 / 1024;
1339 }
1340 
1341 static const struct rate_control_ops mac80211_minstrel_ht = {
1342 	.name = "minstrel_ht",
1343 	.tx_status_noskb = minstrel_ht_tx_status,
1344 	.get_rate = minstrel_ht_get_rate,
1345 	.rate_init = minstrel_ht_rate_init,
1346 	.rate_update = minstrel_ht_rate_update,
1347 	.alloc_sta = minstrel_ht_alloc_sta,
1348 	.free_sta = minstrel_ht_free_sta,
1349 	.alloc = minstrel_ht_alloc,
1350 	.free = minstrel_ht_free,
1351 #ifdef CONFIG_MAC80211_DEBUGFS
1352 	.add_sta_debugfs = minstrel_ht_add_sta_debugfs,
1353 	.remove_sta_debugfs = minstrel_ht_remove_sta_debugfs,
1354 #endif
1355 	.get_expected_throughput = minstrel_ht_get_expected_throughput,
1356 };
1357 
1358 
1359 static void __init init_sample_table(void)
1360 {
1361 	int col, i, new_idx;
1362 	u8 rnd[MCS_GROUP_RATES];
1363 
1364 	memset(sample_table, 0xff, sizeof(sample_table));
1365 	for (col = 0; col < SAMPLE_COLUMNS; col++) {
1366 		prandom_bytes(rnd, sizeof(rnd));
1367 		for (i = 0; i < MCS_GROUP_RATES; i++) {
1368 			new_idx = (i + rnd[i]) % MCS_GROUP_RATES;
1369 			while (sample_table[col][new_idx] != 0xff)
1370 				new_idx = (new_idx + 1) % MCS_GROUP_RATES;
1371 
1372 			sample_table[col][new_idx] = i;
1373 		}
1374 	}
1375 }
1376 
1377 int __init
1378 rc80211_minstrel_ht_init(void)
1379 {
1380 	init_sample_table();
1381 	return ieee80211_rate_control_register(&mac80211_minstrel_ht);
1382 }
1383 
1384 void
1385 rc80211_minstrel_ht_exit(void)
1386 {
1387 	ieee80211_rate_control_unregister(&mac80211_minstrel_ht);
1388 }
1389