diff options
Diffstat (limited to 'drivers/net/wireless/iwlwifi/iwl-4965-commands.h')
| -rw-r--r-- | drivers/net/wireless/iwlwifi/iwl-4965-commands.h | 251 |
1 files changed, 247 insertions, 4 deletions
diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h index cbe91dbe760..7988c752a66 100644 --- a/drivers/net/wireless/iwlwifi/iwl-4965-commands.h +++ b/drivers/net/wireless/iwlwifi/iwl-4965-commands.h @@ -1322,6 +1322,8 @@ struct iwl4965_compressed_ba_resp { /* * REPLY_TX_PWR_TABLE_CMD = 0x97 (command, has simple generic response) + * + * See details under "TXPOWER" in iwl-4965-hw.h. */ struct iwl4965_txpowertable_cmd { u8 band; /* 0: 5 GHz, 1: 2.4 GHz */ @@ -1333,39 +1335,280 @@ struct iwl4965_txpowertable_cmd { /*RS_NEW_API: only TLC_RTS remains and moved to bit 0 */ #define LINK_QUAL_FLAGS_SET_STA_TLC_RTS_MSK (1<<0) +/* # of EDCA prioritized tx fifos */ #define LINK_QUAL_AC_NUM AC_NUM + +/* # entries in rate scale table to support Tx retries */ #define LINK_QUAL_MAX_RETRY_NUM 16 +/* Tx antenna selection values */ #define LINK_QUAL_ANT_A_MSK (1<<0) #define LINK_QUAL_ANT_B_MSK (1<<1) #define LINK_QUAL_ANT_MSK (LINK_QUAL_ANT_A_MSK|LINK_QUAL_ANT_B_MSK) + +/** + * struct iwl4965_link_qual_general_params + * + * Used in REPLY_TX_LINK_QUALITY_CMD + */ struct iwl4965_link_qual_general_params { u8 flags; + + /* No entries at or above this (driver chosen) index contain MIMO */ u8 mimo_delimiter; - u8 single_stream_ant_msk; - u8 dual_stream_ant_msk; + + /* Best single antenna to use for single stream (legacy, SISO). */ + u8 single_stream_ant_msk; /* LINK_QUAL_ANT_* */ + + /* Best antennas to use for MIMO (unused for 4965, assumes both). */ + u8 dual_stream_ant_msk; /* LINK_QUAL_ANT_* */ + + /* + * If driver needs to use different initial rates for different + * EDCA QOS access categories (as implemented by tx fifos 0-3), + * this table will set that up, by indicating the indexes in the + * rs_table[LINK_QUAL_MAX_RETRY_NUM] rate table at which to start. + * Otherwise, driver should set all entries to 0. + * + * Entry usage: + * 0 = Background, 1 = Best Effort (normal), 2 = Video, 3 = Voice + * TX FIFOs above 3 use same value (typically 0) as TX FIFO 3. + */ u8 start_rate_index[LINK_QUAL_AC_NUM]; } __attribute__ ((packed)); +/** + * struct iwl4965_link_qual_agg_params + * + * Used in REPLY_TX_LINK_QUALITY_CMD + */ struct iwl4965_link_qual_agg_params { + + /* Maximum number of uSec in aggregation. + * Driver should set this to 4000 (4 milliseconds). */ __le16 agg_time_limit; + + /* + * Number of Tx retries allowed for a frame, before that frame will + * no longer be considered for the start of an aggregation sequence + * (scheduler will then try to tx it as single frame). + * Driver should set this to 3. + */ u8 agg_dis_start_th; + + /* + * Maximum number of frames in aggregation. + * 0 = no limit (default). 1 = no aggregation. + * Other values = max # frames in aggregation. + */ u8 agg_frame_cnt_limit; + __le32 reserved; } __attribute__ ((packed)); /* * REPLY_TX_LINK_QUALITY_CMD = 0x4e (command, has simple generic response) + * + * For 4965 only; 3945 uses REPLY_RATE_SCALE. + * + * Each station in the 4965's internal station table has its own table of 16 + * Tx rates and modulation modes (e.g. legacy/SISO/MIMO) for retrying Tx when + * an ACK is not received. This command replaces the entire table for + * one station. + * + * NOTE: Station must already be in 4965's station table. Use REPLY_ADD_STA. + * + * The rate scaling procedures described below work well. Of course, other + * procedures are possible, and may work better for particular environments. + * + * + * FILLING THE RATE TABLE + * + * Given a particular initial rate and mode, as determined by the rate + * scaling algorithm described below, the Linux driver uses the following + * formula to fill the rs_table[LINK_QUAL_MAX_RETRY_NUM] rate table in the + * Link Quality command: + * + * + * 1) If using High-throughput (HT) (SISO or MIMO) initial rate: + * a) Use this same initial rate for first 3 entries. + * b) Find next lower available rate using same mode (SISO or MIMO), + * use for next 3 entries. If no lower rate available, switch to + * legacy mode (no FAT channel, no MIMO, no short guard interval). + * c) If using MIMO, set command's mimo_delimiter to number of entries + * using MIMO (3 or 6). + * d) After trying 2 HT rates, switch to legacy mode (no FAT channel, + * no MIMO, no short guard interval), at the next lower bit rate + * (e.g. if second HT bit rate was 54, try 48 legacy), and follow + * legacy procedure for remaining table entries. + * + * 2) If using legacy initial rate: + * a) Use the initial rate for only one entry. + * b) For each following entry, reduce the rate to next lower available + * rate, until reaching the lowest available rate. + * c) When reducing rate, also switch antenna selection. + * d) Once lowest available rate is reached, repeat this rate until + * rate table is filled (16 entries), switching antenna each entry. + * + * + * ACCUMULATING HISTORY + * + * The rate scaling algorithm for 4965, as implemented in Linux driver, uses + * two sets of frame Tx success history: One for the current/active modulation + * mode, and one for a speculative/search mode that is being attempted. If the + * speculative mode turns out to be more effective (i.e. actual transfer + * rate is better), then the driver continues to use the speculative mode + * as the new current active mode. + * + * Each history set contains, separately for each possible rate, data for a + * sliding window of the 62 most recent tx attempts at that rate. The data + * includes a shifting bitmap of success(1)/failure(0), and sums of successful + * and attempted frames, from which the driver can additionally calculate a + * success ratio (success / attempted) and number of failures + * (attempted - success), and control the size of the window (attempted). + * The driver uses the bit map to remove successes from the success sum, as + * the oldest tx attempts fall out of the window. + * + * When the 4965 makes multiple tx attempts for a given frame, each attempt + * might be at a different rate, and have different modulation characteristics + * (e.g. antenna, fat channel, short guard interval), as set up in the rate + * scaling table in the Link Quality command. The driver must determine + * which rate table entry was used for each tx attempt, to determine which + * rate-specific history to update, and record only those attempts that + * match the modulation characteristics of the history set. + * + * When using block-ack (aggregation), all frames are transmitted at the same + * rate, since there is no per-attempt acknowledgement from the destination + * station. The Tx response struct iwl_tx_resp indicates the Tx rate in + * rate_n_flags field. After receiving a block-ack, the driver can update + * history for the entire block all at once. + * + * + * FINDING BEST STARTING RATE: + * + * When working with a selected initial modulation mode (see below), the + * driver attempts to find a best initial rate. The initial rate is the + * first entry in the Link Quality command's rate table. + * + * 1) Calculate actual throughput (success ratio * expected throughput, see + * table below) for current initial rate. Do this only if enough frames + * have been attempted to make the value meaningful: at least 6 failed + * tx attempts, or at least 8 successes. If not enough, don't try rate + * scaling yet. + * + * 2) Find available rates adjacent to current initial rate. Available means: + * a) supported by hardware && + * b) supported by association && + * c) within any constraints selected by user + * + * 3) Gather measured throughputs for adjacent rates. These might not have + * enough history to calculate a throughput. That's okay, we might try + * using one of them anyway! + * + * 4) Try decreasing rate if, for current rate: + * a) success ratio is < 15% || + * b) lower adjacent rate has better measured throughput || + * c) higher adjacent rate has worse throughput, and lower is unmeasured + * + * As a sanity check, if decrease was determined above, leave rate + * unchanged if: + * a) lower rate unavailable + * b) success ratio at current rate > 85% (very good) + * c) current measured throughput is better than expected throughput + * of lower rate (under perfect 100% tx conditions, see table below) + * + * 5) Try increasing rate if, for current rate: + * a) success ratio is < 15% || + * b) both adjacent rates' throughputs are unmeasured (try it!) || + * b) higher adjacent rate has better measured throughput || + * c) lower adjacent rate has worse throughput, and higher is unmeasured + * + * As a sanity check, if increase was determined above, leave rate + * unchanged if: + * a) success ratio at current rate < 70%. This is not particularly + * good performance; higher rate is sure to have poorer success. + * + * 6) Re-evaluate the rate after each tx frame. If working with block- + * acknowledge, history and statistics may be calculated for the entire + * block (including prior history that fits within the history windows), + * before re-evaluation. + * + * FINDING BEST STARTING MODULATION MODE: + * + * After working with a modulation mode for a "while" (and doing rate scaling), + * the driver searches for a new initial mode in an attempt to improve + * throughput. The "while" is measured by numbers of attempted frames: + * + * For legacy mode, search for new mode after: + * 480 successful frames, or 160 failed frames + * For high-throughput modes (SISO or MIMO), search for new mode after: + * 4500 successful frames, or 400 failed frames + * + * Mode switch possibilities are (3 for each mode): + * + * For legacy: + * Change antenna, try SISO (if HT association), try MIMO (if HT association) + * For SISO: + * Change antenna, try MIMO, try shortened guard interval (SGI) + * For MIMO: + * Try SISO antenna A, SISO antenna B, try shortened guard interval (SGI) + * + * When trying a new mode, use the same bit rate as the old/current mode when + * trying antenna switches and shortened guard interval. When switching to + * SISO from MIMO or legacy, or to MIMO from SISO or legacy, use a rate + * for which the expected throughput (under perfect conditions) is about the + * same or slightly better than the actual measured throughput delivered by + * the old/current mode. + * + * Actual throughput can be estimated by multiplying the expected throughput + * by the success ratio (successful / attempted tx frames). Frame size is + * not considered in this calculation; it assumes that frame size will average + * out to be fairly consistent over several samples. The following are + * metric values for expected throughput assuming 100% success ratio. + * Only G band has support for CCK rates: + * + * RATE: 1 2 5 11 6 9 12 18 24 36 48 54 60 + * + * G: 7 13 35 58 40 57 72 98 121 154 177 186 186 + * A: 0 0 0 0 40 57 72 98 121 154 177 186 186 + * SISO 20MHz: 0 0 0 0 42 42 76 102 124 159 183 193 202 + * SGI SISO 20MHz: 0 0 0 0 46 46 82 110 132 168 192 202 211 + * MIMO 20MHz: 0 0 0 0 74 74 123 155 179 214 236 244 251 + * SGI MIMO 20MHz: 0 0 0 0 81 81 131 164 188 222 243 251 257 + * SISO 40MHz: 0 0 0 0 77 77 127 160 184 220 242 250 257 + * SGI SISO 40MHz: 0 0 0 0 83 83 135 169 193 229 250 257 264 + * MIMO 40MHz: 0 0 0 0 123 123 182 214 235 264 279 285 289 + * SGI MIMO 40MHz: 0 0 0 0 131 131 191 222 242 270 284 289 293 + * + * After the new mode has been tried for a short while (minimum of 6 failed + * frames or 8 successful frames), compare success ratio and actual throughput + * estimate of the new mode with the old. If either is better with the new + * mode, continue to use the new mode. + * + * Continue comparing modes until all 3 possibilities have been tried. + * If moving from legacy to HT, try all 3 possibilities from the new HT + * mode. After trying all 3, a best mode is found. Continue to use this mode + * for the longer "while" described above (e.g. 480 successful frames for + * legacy), and then repeat the search process. + * */ struct iwl4965_link_quality_cmd { + + /* Index of destination/recipient station in uCode's station table */ u8 sta_id; u8 reserved1; - __le16 control; + __le16 control; /* not used */ struct iwl4965_link_qual_general_params general_params; struct iwl4965_link_qual_agg_params agg_params; + + /* + * Rate info; when using rate-scaling, Tx command's initial_rate_index + * specifies 1st Tx rate attempted, via index into this table. + * 4965 works its way through table when retrying Tx. + */ struct { - __le32 rate_n_flags; + __le32 rate_n_flags; /* RATE_MCS_*, IWL_RATE_* */ } rs_table[LINK_QUAL_MAX_RETRY_NUM]; __le32 reserved2; } __attribute__ ((packed)); |