drivers/net/wireless/marvell/mwifiex/cfp.c

   1 /*
   2  * NXP Wireless LAN device driver: Channel, Frequence and Power
   3  *
   4  * Copyright 2011-2020 NXP
   5  *
   6  * This software file (the "File") is distributed by NXP
   7  * under the terms of the GNU General Public License Version 2, June 1991
   8  * (the "License").  You may use, redistribute and/or modify this File in
   9  * accordance with the terms and conditions of the License, a copy of which
  10  * is available by writing to the Free Software Foundation, Inc.,
  11  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or on the
  12  * worldwide web at http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt.
  13  *
  14  * THE FILE IS DISTRIBUTED AS-IS, WITHOUT WARRANTY OF ANY KIND, AND THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
  16  * ARE EXPRESSLY DISCLAIMED.  The License provides additional details about
  17  * this warranty disclaimer.
  18  */
  19
  20 #include "decl.h"
  21 #include "ioctl.h"
  22 #include "util.h"
  23 #include "fw.h"
  24 #include "main.h"
  25 #include "cfg80211.h"
  26
  27 /* 100mW */
  28 #define MWIFIEX_TX_PWR_DEFAULT     20
  29 /* 100mW */
  30 #define MWIFIEX_TX_PWR_US_DEFAULT      20
  31 /* 50mW */
  32 #define MWIFIEX_TX_PWR_JP_DEFAULT      16
  33 /* 100mW */
  34 #define MWIFIEX_TX_PWR_FR_100MW        20
  35 /* 10mW */
  36 #define MWIFIEX_TX_PWR_FR_10MW         10
  37 /* 100mW */
  38 #define MWIFIEX_TX_PWR_EMEA_DEFAULT    20
  39
  40 static u8 adhoc_rates_b[B_SUPPORTED_RATES] = { 0x82, 0x84, 0x8b, 0x96, 0 };
  41
  42 static u8 adhoc_rates_g[G_SUPPORTED_RATES] = { 0x8c, 0x12, 0x98, 0x24,
  43                                                0xb0, 0x48, 0x60, 0x6c, 0 };
  44
  45 static u8 adhoc_rates_bg[BG_SUPPORTED_RATES] = { 0x82, 0x84, 0x8b, 0x96,
  46                                                  0x0c, 0x12, 0x18, 0x24,
  47                                                  0x30, 0x48, 0x60, 0x6c, 0 };
  48
  49 static u8 adhoc_rates_a[A_SUPPORTED_RATES] = { 0x8c, 0x12, 0x98, 0x24,
  50                                                0xb0, 0x48, 0x60, 0x6c, 0 };
  51 static u8 supported_rates_a[A_SUPPORTED_RATES] = { 0x0c, 0x12, 0x18, 0x24,
  52                                         0xb0, 0x48, 0x60, 0x6c, 0 };
  53 static u16 mwifiex_data_rates[MWIFIEX_SUPPORTED_RATES_EXT] = { 0x02, 0x04,
  54                                         0x0B, 0x16, 0x00, 0x0C, 0x12, 0x18,
  55                                         0x24, 0x30, 0x48, 0x60, 0x6C, 0x90,
  56                                         0x0D, 0x1A, 0x27, 0x34, 0x4E, 0x68,
  57                                         0x75, 0x82, 0x0C, 0x1B, 0x36, 0x51,
  58                                         0x6C, 0xA2, 0xD8, 0xF3, 0x10E, 0x00 };
  59
  60 static u8 supported_rates_b[B_SUPPORTED_RATES] = { 0x02, 0x04, 0x0b, 0x16, 0 };
  61
  62 static u8 supported_rates_g[G_SUPPORTED_RATES] = { 0x0c, 0x12, 0x18, 0x24,
  63                                         0x30, 0x48, 0x60, 0x6c, 0 };
  64
  65 static u8 supported_rates_bg[BG_SUPPORTED_RATES] = { 0x02, 0x04, 0x0b, 0x0c,
  66                                         0x12, 0x16, 0x18, 0x24, 0x30, 0x48,
  67                                         0x60, 0x6c, 0 };
  68
  69 u16 region_code_index[MWIFIEX_MAX_REGION_CODE] = { 0x00, 0x10, 0x20, 0x30,
  70                                                 0x31, 0x32, 0x40, 0x41, 0x50 };
  71
  72 static u8 supported_rates_n[N_SUPPORTED_RATES] = { 0x02, 0x04, 0 };
  73
  74 /* For every mcs_rate line, the first 8 bytes are for stream 1x1,
  75  * and all 16 bytes are for stream 2x2.
  76  */
  77 static const u16 mcs_rate[4][16] = {
  78         /* LGI 40M */
  79         { 0x1b, 0x36, 0x51, 0x6c, 0xa2, 0xd8, 0xf3, 0x10e,
  80           0x36, 0x6c, 0xa2, 0xd8, 0x144, 0x1b0, 0x1e6, 0x21c },
  81
  82         /* SGI 40M */
  83         { 0x1e, 0x3c, 0x5a, 0x78, 0xb4, 0xf0, 0x10e, 0x12c,
  84           0x3c, 0x78, 0xb4, 0xf0, 0x168, 0x1e0, 0x21c, 0x258 },
  85
  86         /* LGI 20M */
  87         { 0x0d, 0x1a, 0x27, 0x34, 0x4e, 0x68, 0x75, 0x82,
  88           0x1a, 0x34, 0x4e, 0x68, 0x9c, 0xd0, 0xea, 0x104 },
  89
  90         /* SGI 20M */
  91         { 0x0e, 0x1c, 0x2b, 0x39, 0x56, 0x73, 0x82, 0x90,
  92           0x1c, 0x39, 0x56, 0x73, 0xad, 0xe7, 0x104, 0x120 }
  93 };
  94
  95 /* AC rates */
  96 static const u16 ac_mcs_rate_nss1[8][10] = {
  97         /* LG 160M */
  98         { 0x75, 0xEA, 0x15F, 0x1D4, 0x2BE, 0x3A8, 0x41D,
  99           0x492, 0x57C, 0x618 },
 100
 101         /* SG 160M */
 102         { 0x82, 0x104, 0x186, 0x208, 0x30C, 0x410, 0x492,
 103           0x514, 0x618, 0x6C6 },
 104
 105         /* LG 80M */
 106         { 0x3B, 0x75, 0xB0, 0xEA, 0x15F, 0x1D4, 0x20F,
 107           0x249, 0x2BE, 0x30C },
 108
 109         /* SG 80M */
 110         { 0x41, 0x82, 0xC3, 0x104, 0x186, 0x208, 0x249,
 111           0x28A, 0x30C, 0x363 },
 112
 113         /* LG 40M */
 114         { 0x1B, 0x36, 0x51, 0x6C, 0xA2, 0xD8, 0xF3,
 115           0x10E, 0x144, 0x168 },
 116
 117         /* SG 40M */
 118         { 0x1E, 0x3C, 0x5A, 0x78, 0xB4, 0xF0, 0x10E,
 119           0x12C, 0x168, 0x190 },
 120
 121         /* LG 20M */
 122         { 0xD, 0x1A, 0x27, 0x34, 0x4E, 0x68, 0x75, 0x82, 0x9C, 0x00 },
 123
 124         /* SG 20M */
 125         { 0xF, 0x1D, 0x2C, 0x3A, 0x57, 0x74, 0x82, 0x91, 0xAE, 0x00 },
 126 };
 127
 128 /* NSS2 note: the value in the table is 2 multiplier of the actual rate */
 129 static const u16 ac_mcs_rate_nss2[8][10] = {
 130         /* LG 160M */
 131         { 0xEA, 0x1D4, 0x2BE, 0x3A8, 0x57C, 0x750, 0x83A,
 132           0x924, 0xAF8, 0xC30 },
 133
 134         /* SG 160M */
 135         { 0x104, 0x208, 0x30C, 0x410, 0x618, 0x820, 0x924,
 136           0xA28, 0xC30, 0xD8B },
 137
 138         /* LG 80M */
 139         { 0x75, 0xEA, 0x15F, 0x1D4, 0x2BE, 0x3A8, 0x41D,
 140           0x492, 0x57C, 0x618 },
 141
 142         /* SG 80M */
 143         { 0x82, 0x104, 0x186, 0x208, 0x30C, 0x410, 0x492,
 144           0x514, 0x618, 0x6C6 },
 145
 146         /* LG 40M */
 147         { 0x36, 0x6C, 0xA2, 0xD8, 0x144, 0x1B0, 0x1E6,
 148           0x21C, 0x288, 0x2D0 },
 149
 150         /* SG 40M */
 151         { 0x3C, 0x78, 0xB4, 0xF0, 0x168, 0x1E0, 0x21C,
 152           0x258, 0x2D0, 0x320 },
 153
 154         /* LG 20M */
 155         { 0x1A, 0x34, 0x4A, 0x68, 0x9C, 0xD0, 0xEA, 0x104,
 156           0x138, 0x00 },
 157
 158         /* SG 20M */
 159         { 0x1D, 0x3A, 0x57, 0x74, 0xAE, 0xE6, 0x104, 0x121,
 160           0x15B, 0x00 },
 161 };
 162
 163 struct region_code_mapping {
 164         u8 code;
 165         u8 region[IEEE80211_COUNTRY_STRING_LEN];
 166 };
 167
 168 static struct region_code_mapping region_code_mapping_t[] = {
 169         { 0x10, "US " }, /* US FCC */
 170         { 0x20, "CA " }, /* IC Canada */
 171         { 0x30, "FR " }, /* France */
 172         { 0x31, "ES " }, /* Spain */
 173         { 0x32, "FR " }, /* France */
 174         { 0x40, "JP " }, /* Japan */
 175         { 0x41, "JP " }, /* Japan */
 176         { 0x50, "CN " }, /* China */
 177 };
 178
 179 /* This function converts integer code to region string */
 180 u8 *mwifiex_11d_code_2_region(u8 code)
 181 {
 182         u8 i;
 183
 184         /* Look for code in mapping table */
 185         for (i = 0; i < ARRAY_SIZE(region_code_mapping_t); i++)
 186                 if (region_code_mapping_t[i].code == code)
 187                         return region_code_mapping_t[i].region;
 188
 189         return NULL;
 190 }
 191
 192 /*
 193  * This function maps an index in supported rates table into
 194  * the corresponding data rate.
 195  */
 196 u32 mwifiex_index_to_acs_data_rate(struct mwifiex_private *priv,
 197                                    u8 index, u8 ht_info)
 198 {
 199         u32 rate = 0;
 200         u8 mcs_index = 0;
 201         u8 bw = 0;
 202         u8 gi = 0;
 203
 204         if ((ht_info & 0x3) == MWIFIEX_RATE_FORMAT_VHT) {
 205                 mcs_index = min(index & 0xF, 9);
 206
 207                 /* 20M: bw=0, 40M: bw=1, 80M: bw=2, 160M: bw=3 */
 208                 bw = (ht_info & 0xC) >> 2;
 209
 210                 /* LGI: gi =0, SGI: gi = 1 */
 211                 gi = (ht_info & 0x10) >> 4;
 212
 213                 if ((index >> 4) == 1)  /* NSS = 2 */
 214                         rate = ac_mcs_rate_nss2[2 * (3 - bw) + gi][mcs_index];
 215                 else                    /* NSS = 1 */
 216                         rate = ac_mcs_rate_nss1[2 * (3 - bw) + gi][mcs_index];
 217         } else if ((ht_info & 0x3) == MWIFIEX_RATE_FORMAT_HT) {
 218                 /* 20M: bw=0, 40M: bw=1 */
 219                 bw = (ht_info & 0xC) >> 2;
 220
 221                 /* LGI: gi =0, SGI: gi = 1 */
 222                 gi = (ht_info & 0x10) >> 4;
 223
 224                 if (index == MWIFIEX_RATE_BITMAP_MCS0) {
 225                         if (gi == 1)
 226                                 rate = 0x0D;    /* MCS 32 SGI rate */
 227                         else
 228                                 rate = 0x0C;    /* MCS 32 LGI rate */
 229                 } else if (index < 16) {
 230                         if ((bw == 1) || (bw == 0))
 231                                 rate = mcs_rate[2 * (1 - bw) + gi][index];
 232                         else
 233                                 rate = mwifiex_data_rates[0];
 234                 } else {
 235                         rate = mwifiex_data_rates[0];
 236                 }
 237         } else {
 238                 /* 11n non-HT rates */
 239                 if (index >= MWIFIEX_SUPPORTED_RATES_EXT)
 240                         index = 0;
 241                 rate = mwifiex_data_rates[index];
 242         }
 243
 244         return rate;
 245 }
 246
 247 /* This function maps an index in supported rates table into
 248  * the corresponding data rate.
 249  */
 250 u32 mwifiex_index_to_data_rate(struct mwifiex_private *priv,
 251                                u8 index, u8 ht_info)
 252 {
 253         u32 mcs_num_supp =
 254                 (priv->adapter->user_dev_mcs_support == HT_STREAM_2X2) ? 16 : 8;
 255         u32 rate;
 256
 257         if (priv->adapter->is_hw_11ac_capable)
 258                 return mwifiex_index_to_acs_data_rate(priv, index, ht_info);
 259
 260         if (ht_info & BIT(0)) {
 261                 if (index == MWIFIEX_RATE_BITMAP_MCS0) {
 262                         if (ht_info & BIT(2))
 263                                 rate = 0x0D;    /* MCS 32 SGI rate */
 264                         else
 265                                 rate = 0x0C;    /* MCS 32 LGI rate */
 266                 } else if (index < mcs_num_supp) {
 267                         if (ht_info & BIT(1)) {
 268                                 if (ht_info & BIT(2))
 269                                         /* SGI, 40M */
 270                                         rate = mcs_rate[1][index];
 271                                 else
 272                                         /* LGI, 40M */
 273                                         rate = mcs_rate[0][index];
 274                         } else {
 275                                 if (ht_info & BIT(2))
 276                                         /* SGI, 20M */
 277                                         rate = mcs_rate[3][index];
 278                                 else
 279                                         /* LGI, 20M */
 280                                         rate = mcs_rate[2][index];
 281                         }
 282                 } else
 283                         rate = mwifiex_data_rates[0];
 284         } else {
 285                 if (index >= MWIFIEX_SUPPORTED_RATES_EXT)
 286                         index = 0;
 287                 rate = mwifiex_data_rates[index];
 288         }
 289         return rate;
 290 }
 291
 292 /*
 293  * This function returns the current active data rates.
 294  *
 295  * The result may vary depending upon connection status.
 296  */
 297 u32 mwifiex_get_active_data_rates(struct mwifiex_private *priv, u8 *rates)
 298 {
 299         if (!priv->media_connected)
 300                 return mwifiex_get_supported_rates(priv, rates);
 301         else
 302                 return mwifiex_copy_rates(rates, 0,
 303                                           priv->curr_bss_params.data_rates,
 304                                           priv->curr_bss_params.num_of_rates);
 305 }
 306
 307 /*
 308  * This function locates the Channel-Frequency-Power triplet based upon
 309  * band and channel/frequency parameters.
 310  */
 311 struct mwifiex_chan_freq_power *
 312 mwifiex_get_cfp(struct mwifiex_private *priv, u8 band, u16 channel, u32 freq)
 313 {
 314         struct mwifiex_chan_freq_power *cfp = NULL;
 315         struct ieee80211_supported_band *sband;
 316         struct ieee80211_channel *ch = NULL;
 317         int i;
 318
 319         if (!channel && !freq)
 320                 return cfp;
 321
 322         if (mwifiex_band_to_radio_type(band) == HostCmd_SCAN_RADIO_TYPE_BG)
 323                 sband = priv->wdev.wiphy->bands[NL80211_BAND_2GHZ];
 324         else
 325                 sband = priv->wdev.wiphy->bands[NL80211_BAND_5GHZ];
 326
 327         if (!sband) {
 328                 mwifiex_dbg(priv->adapter, ERROR,
 329                             "%s: cannot find cfp by band %d\n",
 330                             __func__, band);
 331                 return cfp;
 332         }
 333
 334         for (i = 0; i < sband->n_channels; i++) {
 335                 ch = &sband->channels[i];
 336
 337                 if (ch->flags & IEEE80211_CHAN_DISABLED)
 338                         continue;
 339
 340                 if (freq) {
 341                         if (ch->center_freq == freq)
 342                                 break;
 343                 } else {
 344                         /* find by valid channel*/
 345                         if (ch->hw_value == channel ||
 346                             channel == FIRST_VALID_CHANNEL)
 347                                 break;
 348                 }
 349         }
 350         if (i == sband->n_channels) {
 351                 mwifiex_dbg(priv->adapter, WARN,
 352                             "%s: cannot find cfp by band %d\t"
 353                             "& channel=%d freq=%d\n",
 354                             __func__, band, channel, freq);
 355         } else {
 356                 if (!ch)
 357                         return cfp;
 358
 359                 priv->cfp.channel = ch->hw_value;
 360                 priv->cfp.freq = ch->center_freq;
 361                 priv->cfp.max_tx_power = ch->max_power;
 362                 cfp = &priv->cfp;
 363         }
 364
 365         return cfp;
 366 }
 367
 368 /*
 369  * This function checks if the data rate is set to auto.
 370  */
 371 u8
 372 mwifiex_is_rate_auto(struct mwifiex_private *priv)
 373 {
 374         u32 i;
 375         int rate_num = 0;
 376
 377         for (i = 0; i < ARRAY_SIZE(priv->bitmap_rates); i++)
 378                 if (priv->bitmap_rates[i])
 379                         rate_num++;
 380
 381         if (rate_num > 1)
 382                 return true;
 383         else
 384                 return false;
 385 }
 386
 387 /* This function gets the supported data rates from bitmask inside
 388  * cfg80211_scan_request.
 389  */
 390 u32 mwifiex_get_rates_from_cfg80211(struct mwifiex_private *priv,
 391                                     u8 *rates, u8 radio_type)
 392 {
 393         struct wiphy *wiphy = priv->adapter->wiphy;
 394         struct cfg80211_scan_request *request = priv->scan_request;
 395         u32 num_rates, rate_mask;
 396         struct ieee80211_supported_band *sband;
 397         int i;
 398
 399         if (radio_type) {
 400                 sband = wiphy->bands[NL80211_BAND_5GHZ];
 401                 if (WARN_ON_ONCE(!sband))
 402                         return 0;
 403                 rate_mask = request->rates[NL80211_BAND_5GHZ];
 404         } else {
 405                 sband = wiphy->bands[NL80211_BAND_2GHZ];
 406                 if (WARN_ON_ONCE(!sband))
 407                         return 0;
 408                 rate_mask = request->rates[NL80211_BAND_2GHZ];
 409         }
 410
 411         num_rates = 0;
 412         for (i = 0; i < sband->n_bitrates; i++) {
 413                 if ((BIT(i) & rate_mask) == 0)
 414                         continue; /* skip rate */
 415                 rates[num_rates++] = (u8)(sband->bitrates[i].bitrate / 5);
 416         }
 417
 418         return num_rates;
 419 }
 420
 421 /* This function gets the supported data rates. The function works in
 422  * both Ad-Hoc and infra mode by printing the band and returning the
 423  * data rates.
 424  */
 425 u32 mwifiex_get_supported_rates(struct mwifiex_private *priv, u8 *rates)
 426 {
 427         u32 k = 0;
 428         struct mwifiex_adapter *adapter = priv->adapter;
 429
 430         if (priv->bss_mode == NL80211_IFTYPE_STATION ||
 431             priv->bss_mode == NL80211_IFTYPE_P2P_CLIENT) {
 432                 switch (adapter->config_bands) {
 433                 case BAND_B:
 434                         mwifiex_dbg(adapter, INFO, "info: infra band=%d\t"
 435                                     "supported_rates_b\n",
 436                                     adapter->config_bands);
 437                         k = mwifiex_copy_rates(rates, k, supported_rates_b,
 438                                                sizeof(supported_rates_b));
 439                         break;
 440                 case BAND_G:
 441                 case BAND_G | BAND_GN:
 442                         mwifiex_dbg(adapter, INFO, "info: infra band=%d\t"
 443                                     "supported_rates_g\n",
 444                                     adapter->config_bands);
 445                         k = mwifiex_copy_rates(rates, k, supported_rates_g,
 446                                                sizeof(supported_rates_g));
 447                         break;
 448                 case BAND_B | BAND_G:
 449                 case BAND_A | BAND_B | BAND_G:
 450                 case BAND_A | BAND_B:
 451                 case BAND_A | BAND_B | BAND_G | BAND_GN | BAND_AN:
 452                 case BAND_A | BAND_B | BAND_G | BAND_GN | BAND_AN | BAND_AAC:
 453                 case BAND_B | BAND_G | BAND_GN:
 454                         mwifiex_dbg(adapter, INFO, "info: infra band=%d\t"
 455                                     "supported_rates_bg\n",
 456                                     adapter->config_bands);
 457                         k = mwifiex_copy_rates(rates, k, supported_rates_bg,
 458                                                sizeof(supported_rates_bg));
 459                         break;
 460                 case BAND_A:
 461                 case BAND_A | BAND_G:
 462                         mwifiex_dbg(adapter, INFO, "info: infra band=%d\t"
 463                                     "supported_rates_a\n",
 464                                     adapter->config_bands);
 465                         k = mwifiex_copy_rates(rates, k, supported_rates_a,
 466                                                sizeof(supported_rates_a));
 467                         break;
 468                 case BAND_AN:
 469                 case BAND_A | BAND_AN:
 470                 case BAND_A | BAND_AN | BAND_AAC:
 471                 case BAND_A | BAND_G | BAND_AN | BAND_GN:
 472                 case BAND_A | BAND_G | BAND_AN | BAND_GN | BAND_AAC:
 473                         mwifiex_dbg(adapter, INFO, "info: infra band=%d\t"
 474                                     "supported_rates_a\n",
 475                                     adapter->config_bands);
 476                         k = mwifiex_copy_rates(rates, k, supported_rates_a,
 477                                                sizeof(supported_rates_a));
 478                         break;
 479                 case BAND_GN:
 480                         mwifiex_dbg(adapter, INFO, "info: infra band=%d\t"
 481                                     "supported_rates_n\n",
 482                                     adapter->config_bands);
 483                         k = mwifiex_copy_rates(rates, k, supported_rates_n,
 484                                                sizeof(supported_rates_n));
 485                         break;
 486                 }
 487         } else {
 488                 /* Ad-hoc mode */
 489                 switch (adapter->adhoc_start_band) {
 490                 case BAND_B:
 491                         mwifiex_dbg(adapter, INFO, "info: adhoc B\n");
 492                         k = mwifiex_copy_rates(rates, k, adhoc_rates_b,
 493                                                sizeof(adhoc_rates_b));
 494                         break;
 495                 case BAND_G:
 496                 case BAND_G | BAND_GN:
 497                         mwifiex_dbg(adapter, INFO, "info: adhoc G only\n");
 498                         k = mwifiex_copy_rates(rates, k, adhoc_rates_g,
 499                                                sizeof(adhoc_rates_g));
 500                         break;
 501                 case BAND_B | BAND_G:
 502                 case BAND_B | BAND_G | BAND_GN:
 503                         mwifiex_dbg(adapter, INFO, "info: adhoc BG\n");
 504                         k = mwifiex_copy_rates(rates, k, adhoc_rates_bg,
 505                                                sizeof(adhoc_rates_bg));
 506                         break;
 507                 case BAND_A:
 508                 case BAND_A | BAND_AN:
 509                         mwifiex_dbg(adapter, INFO, "info: adhoc A\n");
 510                         k = mwifiex_copy_rates(rates, k, adhoc_rates_a,
 511                                                sizeof(adhoc_rates_a));
 512                         break;
 513                 }
 514         }
 515
 516         return k;
 517 }
 518
 519 u8 mwifiex_adjust_data_rate(struct mwifiex_private *priv,
 520                             u8 rx_rate, u8 rate_info)
 521 {
 522         u8 rate_index = 0;
 523
 524         /* HT40 */
 525         if ((rate_info & BIT(0)) && (rate_info & BIT(1)))
 526                 rate_index = MWIFIEX_RATE_INDEX_MCS0 +
 527                              MWIFIEX_BW20_MCS_NUM + rx_rate;
 528         else if (rate_info & BIT(0)) /* HT20 */
 529                 rate_index = MWIFIEX_RATE_INDEX_MCS0 + rx_rate;
 530         else
 531                 rate_index = (rx_rate > MWIFIEX_RATE_INDEX_OFDM0) ?
 532                               rx_rate - 1 : rx_rate;
 533
 534         if (rate_index >= MWIFIEX_MAX_AC_RX_RATES)
 535                 rate_index = MWIFIEX_MAX_AC_RX_RATES - 1;
 536
 537         return rate_index;
 538 }