[PATCH wireless-next 16/35] wifi: mm81x: add mmrc.c

[Lachlan Hodges]

(Patches split per file for review, see cover letter for more
information)

Signed-off-by: Lachlan Hodges <lachlan.hodges@xxxxxxxxxxxxxx>
---
 drivers/net/wireless/morsemicro/mm81x/mmrc.c | 1353 ++++++++++++++++++
 1 file changed, 1353 insertions(+)
 create mode 100644 drivers/net/wireless/morsemicro/mm81x/mmrc.c

diff --git a/drivers/net/wireless/morsemicro/mm81x/mmrc.c b/drivers/net/wireless/morsemicro/mm81x/mmrc.c
new file mode 100644
index 000000000000..237055df2f21
--- /dev/null
+++ b/drivers/net/wireless/morsemicro/mm81x/mmrc.c
@@ -0,0 +1,1353 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2017-2026 Morse Micro
+ */
+#include "mmrc.h"
+
+/*
+ * The default packet size in bits used for calculated throughput of a given
+ * rate
+ */
+#define DEFAULT_PACKET_SIZE_BITS 9600
+
+/*
+ * The default packet size in bytes used for calculating retries for a given
+ * rate
+ */
+#define DEFAULT_PACKET_SIZE_BYTES 1200
+
+/* The sample frequencies at different stages */
+#define LOOKAROUND_RATE_INIT 5
+#define LOOKAROUND_RATE_NORMAL 50
+#define LOOKAROUND_RATE_STABLE 100
+
+/* The thresholds for stability stages */
+#define STABILITY_CNT_THRESHOLD_INIT 20
+#define STABILITY_CNT_THRESHOLD_NORMAL 50
+#define STABILITY_CNT_THRESHOLD_STABLE 100
+
+/* The backoff step size for the counter */
+#define STABILITY_BACKOFF_STEP 2
+
+/*
+ * The packet success threshold for attempting slower lookaround rates
+ */
+/*
+ * Force a look around if there haven't been any for this number of cycles
+ */
+#define LOOKAROUND_MAX_RC_CYCLES 5
+
+/*
+ * Number of attempts for each lookaround rate within at most two RC cycles
+ * if there are enough packets
+ */
+#define LOOKAROUND_RATE_ATTEMPTS 4
+
+/*
+ * Limit the number of times we try to pick a theoretically better rate to
+ * sample. Necessary so we don't stall the CPU, due to constantly picking worse
+ * rates.
+ */
+#define LOOKAROUND_FAIL_MAX 200
+
+/*
+ * Initial and reset probability per rate in the table
+ * Changing this value will have a severe implication on the current heuristic
+ * It could mean that some rates will have better probability throughput even
+ * with no edivence and so will cause unexpected changes in the rate table
+ */
+#define RATE_INIT_PROBABILITY 0
+
+/*
+ * The lowest number of MPDUs within acknowledged AMPDUs that can be used for
+ * rate stats
+ */
+#define AMPDU_STATS_MIN 2
+
+/*
+ * The lowest number of stats to be used for processing in NORMAL lookaround
+ * mode
+ */
+#define STATS_MIN_NORMAL 2
+
+/*
+ * The lowest number of stats to be used for processing in INIT lookaround
+ * mode
+ */
+#define STATS_MIN_INIT 1
+
+/* The lowest probability value considered for recognising a dip */
+#define PROBABILITY_DIP_MIN 20
+
+/* The lowest probability value for recovering from a dip */
+#define PROBABILITY_DIP_RECOVERY_MIN 40
+
+/*
+ * The time cap on rate allocation for multiple attempts. If a single attempt
+ * exceeds this window, no additional attempts will be generated
+ */
+#define MAX_WINDOW_ATTEMPT_TIME 4000
+
+/* The time window for all rates in rate table */
+#define RATE_WINDOW_MICROSECONDS 24000
+
+/*
+ * EWMA is the alpha coefficient in the exponential weighting moving average
+ * filter used for probability updates.
+ *
+ * Y[n] = X[n] * (100 - EWMA) + (Y[n-1] * EWMA)
+ *	  -------------------------------------
+ *			   100
+ *
+ */
+#define EWMA 75
+
+/*
+ * Evidence scaling to allow for one decimal place. Needed for low
+ * throughput, otherwise the history decays in a single cycle.
+ */
+#define EVIDENCE_SCALE 5
+
+/*
+ * Evidence maximum to ensure history doesn't decay too slowly when
+ * there is a lot of historical data.
+ */
+#define EVIDENCE_MAX 100
+
+/*
+ * This fixed point conversion multiplies a value by one and shifts it
+ * accordingly to account for the fixed point shifting at the return of a
+ * function
+ */
+#define FP_8_MULT_1 256
+
+/* Fixed point conversion for 2.1 * 2^8 used for 4MHz symbol multiplication */
+#define FP_8_4MHZ 537
+
+/* Fixed point conversion for 4.5 * 2^8 used for 8MHz symbol multiplication */
+#define FP_8_8MHZ 1152
+
+/* Fixed point conversion for 9.0 * 2^8 used for 16MHz symbol multiplication */
+#define FP_8_16MHZ 2301
+
+/*
+ * Fixed point conversion for 3.6 * 2^8 used for long guard symbol tx time
+ * multiplication
+ */
+#define FP_8_LONG_GUARD_SYMBOL_TIME 1024
+
+/*
+ * Fixed point conversion for 4.0 * 2^8 used for short guard symbol tx time
+ * multiplication
+ */
+#define FP_8_SHORT_GUARD_SYMBOL_TIME 921
+
+/*
+ * Shift value to shift back our FP conversions
+ */
+#define FP_8_SHIFT 8
+
+/*
+ * Limit to count of consecutive variations in one direction
+ */
+#define MAX_VARIATION_DIRECTION 5
+
+/*
+ * Threshold for considering consecutive variation direction as variation
+ * or not
+ */
+#define VARIATION_DIRECTION_THRESHOLD 3
+
+/* EWMA percentage value for averaging the best rate probability variation */
+#define VARIATION_EWMA 95
+
+/* Percentage variation regarded as minor */
+#define MINOR_VARIATION_THRESHOLD 1
+
+/* Percentage variation regarded as moderate */
+#define MODERATE_VARIATION_THRESHOLD 3
+
+/* Percentage variation regarded as significant */
+#define SIGNIFICANT_VARIATION_THRESHOLD 5
+
+/* If the best rate changes twice in this number of cycles, it is unstable */
+#define BEST_RATE_UNSTABLE_THRESHOLD 4
+
+/*
+ * Once the best rate is unchanged for this number of cycles it has
+ * converged
+ */
+#define BEST_RATE_CONVERGED_THRESHOLD 10
+
+/* RSSI threshold for short range */
+#define MMRC_SHORT_RANGE_RSSI_LIMIT -70
+
+/* RSSI threshold for mid range */
+#define MMRC_MID_RANGE_RSSI_LIMIT -85
+
+#define MMRC_MAX_BW(bw_caps)                                      \
+	(((bw_caps) & MMRC_MASK(MMRC_BW_16MHZ)) ? MMRC_BW_16MHZ : \
+	 ((bw_caps) & MMRC_MASK(MMRC_BW_8MHZ))	? MMRC_BW_8MHZ :  \
+	 ((bw_caps) & MMRC_MASK(MMRC_BW_4MHZ))	? MMRC_BW_4MHZ :  \
+	 ((bw_caps) & MMRC_MASK(MMRC_BW_2MHZ))	? MMRC_BW_2MHZ :  \
+						  MMRC_BW_1MHZ)
+
+/*
+ * This table stores the number of bits per symbols used for MCS0-MCS9 based
+ * on 20MHz and 1SS
+ */
+static const u32 sym_table[10] = { 24, 36, 48, 72, 96, 144, 192, 216, 256, 288 };
+
+/*
+ * Calculate which bit is the nth bit set in an integer based flag.
+ */
+static u8 nth_bit(u16 in, u16 index)
+{
+	u32 i;
+	u8 count = 0;
+
+	for (i = 0; count != index + 1; i++) {
+		if (((1u << i) & in) != 0)
+			count++;
+	}
+
+	return i - 1;
+}
+
+/*
+ * Calculate the input bit's index among all the set bits in an integer
+ * based flag.
+ */
+static u16 bit_index(u16 in, u32 bit_pos)
+{
+	u16 i;
+	u16 index = 0;
+
+	for (i = 0; i != bit_pos + 1; i++) {
+		if (((1u << i) & in) != 0)
+			index++;
+	}
+
+	if (index == 0) {
+		/* Could not match bit pos to caps */
+		return 0;
+	}
+
+	return index - 1;
+}
+
+static u16 rows_from_sta_caps(struct mmrc_sta_capabilities *caps)
+{
+	u16 rows = 0;
+	u8 n_rates = BIT_COUNT(caps->rates);
+
+	/* Taking MCS10 into account as it is relevant for 1 MHz entries */
+	if (caps->rates & MMRC_MASK(MMRC_MCS10)) {
+		n_rates -= 1;
+		rows = 2;
+	}
+
+	rows += (BIT_COUNT(caps->bandwidth) * n_rates * BIT_COUNT(caps->guard) *
+		 BIT_COUNT(caps->spatial_streams));
+
+	return rows;
+}
+
+static void rate_update_index(struct mmrc_table *tb, struct mmrc_rate *rate)
+{
+	u16 index = 0;
+	/* Information about our rates */
+	u16 bw = BIT_COUNT(tb->caps.bandwidth);
+	u16 streams = BIT_COUNT(tb->caps.spatial_streams);
+	u16 guard = BIT_COUNT(tb->caps.guard);
+	u16 rows = rows_from_sta_caps(&tb->caps);
+
+	index = bit_index(tb->caps.guard, rate->guard) +
+		bit_index(tb->caps.bandwidth, rate->bw) * guard +
+		bit_index(tb->caps.spatial_streams, rate->ss) * guard * bw +
+		bit_index(tb->caps.rates, rate->rate) * bw * streams * guard;
+
+	if (index >= rows)
+		index = 0;
+
+	rate->index = index;
+}
+
+static struct mmrc_rate get_rate_row(struct mmrc_table *tb, u16 index)
+{
+	struct mmrc_rate rate;
+	u16 ss_index;
+
+	/* Information about our rates */
+	u16 mcs = BIT_COUNT(tb->caps.rates);
+	u16 bw = BIT_COUNT(tb->caps.bandwidth);
+	u16 streams = BIT_COUNT(tb->caps.spatial_streams);
+	u16 guard = BIT_COUNT(tb->caps.guard);
+	u16 total_caps = mcs * bw * streams * guard;
+
+	/* Find our MCS */
+	u16 rows = total_caps / mcs;
+	u16 mcs_index = index / rows;
+	u16 mcs_modulo = index % rows;
+
+	mcs = nth_bit(tb->caps.rates, mcs_index);
+
+	/* Find our spatial stream */
+	rows = rows / streams;
+	streams = nth_bit(tb->caps.spatial_streams, mcs_modulo / rows);
+
+	/* Find our bandwidth */
+	ss_index = index % rows;
+	rows = rows / bw;
+	bw = nth_bit(tb->caps.bandwidth, ss_index / rows);
+
+	/* Find our guard */
+	guard = nth_bit(tb->caps.guard, index % guard);
+
+	/* Add range checks to keep scan-build happy */
+	if (bw >= MMRC_BW_MAX)
+		bw = MMRC_BW_1MHZ;
+
+	if (guard >= MMRC_GUARD_MAX)
+		guard = MMRC_GUARD_LONG;
+
+	/* Validate guard against capability */
+	if (guard == MMRC_GUARD_SHORT &&
+	    !(tb->caps.sgi_per_bw & SGI_PER_BW(bw)))
+		guard = MMRC_GUARD_LONG;
+
+	/* Create our rate row and send it */
+	rate.bw = MMRC_BW_TO_BITFIELD(bw);
+	rate.ss = MMRC_SS_TO_BITFIELD(streams);
+	rate.rate = MMRC_RATE_TO_BITFIELD(mcs);
+	rate.guard = MMRC_GUARD_TO_BITFIELD(guard);
+	rate.attempts = 0;
+	rate.flags = 0;
+
+	/* Update index as bw or guard may have changed */
+	rate_update_index(tb, &rate);
+
+	return rate;
+}
+
+size_t mmrc_memory_required_for_caps(struct mmrc_sta_capabilities *caps)
+{
+	return sizeof(struct mmrc_table) +
+	       rows_from_sta_caps(caps) * sizeof(struct mmrc_stats_table);
+}
+
+static u32 calculate_bits_per_symbol(struct mmrc_rate *rate)
+{
+	u32 bps;
+
+	/* If MCS10 is selected we return 2*MCS0 Symbols */
+	if (rate->rate == MMRC_MCS10)
+		return 6;
+
+	/* Confirm that the rate is valid for the sym_table lookup */
+	if (rate->rate >= MMRC_MCS_UNUSED) {
+		pr_err("%s: Invalid MCS rate %d for sym_table lookup\n",
+		       __func__, rate->rate);
+		return 1;
+	}
+
+	/*
+	 * Coversion from 20MHz as in sym_table to:
+	 * 40MHz   ==	x 2.1
+	 * 80MHz   ==	x 4.5
+	 * 160MHz  ==	x 9.0
+	 */
+	bps = sym_table[rate->rate];
+	switch (rate->bw) {
+	case (MMRC_BW_4MHZ):
+		bps *= FP_8_4MHZ;
+		break;
+	case (MMRC_BW_8MHZ):
+		bps *= FP_8_8MHZ;
+		break;
+	case (MMRC_BW_16MHZ):
+		bps *= FP_8_16MHZ;
+		break;
+	case (MMRC_BW_1MHZ):
+		bps = sym_table[rate->rate] * 24 / 52;
+		bps *= FP_8_MULT_1;
+		break;
+	case (MMRC_BW_2MHZ):
+	case (MMRC_BW_MAX):
+	default:
+		bps *= FP_8_MULT_1;
+		break;
+	}
+	/* SS + 1 because mmrc_spatial_stream starts at 0 */
+	return ((rate->ss + 1) * bps) >> FP_8_SHIFT;
+}
+
+static u32 get_tx_time(struct mmrc_rate *rate)
+{
+	u32 tx = 0;
+	u32 n_sym;
+	u32 avg_bits;
+
+	/* Calculate tx time based on a default packet size */
+	avg_bits = DEFAULT_PACKET_SIZE_BITS;
+
+	/* Number of bits per symbol for this rate */
+	n_sym = calculate_bits_per_symbol(rate);
+
+	/* In case of bad calcuation/parameter use lowest value */
+	n_sym = n_sym == 0 ? sym_table[0] : n_sym;
+
+	/* number of symbols in default packet size */
+	n_sym = avg_bits / n_sym;
+
+	/* tx is time to transmit average packet in us */
+	switch (rate->guard) {
+	case (MMRC_GUARD_LONG):
+		tx = n_sym * FP_8_LONG_GUARD_SYMBOL_TIME;
+		break;
+	case (MMRC_GUARD_SHORT):
+		tx = n_sym * FP_8_SHORT_GUARD_SYMBOL_TIME;
+		break;
+	default:
+		return 0;
+	}
+
+	return (tx * 10) >> FP_8_SHIFT;
+}
+
+u32 mmrc_calculate_theoretical_throughput(struct mmrc_rate rate)
+{
+	static const u32 s1g_tpt_lgi[4][11] = {
+		{ 300, 600, 900, 1200, 1800, 2400, 2700, 3000, 3600, 4000,
+		  150 },
+		{ 650, 1300, 1950, 2600, 3900, 5200, 5850, 6500, 7800, 0, 0 },
+		{ 1350, 2700, 4050, 5400, 8100, 10800, 12150, 13500, 16200,
+		  18000, 0 },
+		{ 2925, 5850, 8775, 11700, 17550, 23400, 26325, 29250, 35100,
+		  39000, 0 },
+	};
+
+	static const u32 s1g_tpt_sgi[4][11] = {
+		{ 333, 666, 1000, 1333, 2000, 2666, 3000, 3333, 4000, 4444,
+		  166 },
+		{ 722, 1444, 2166, 2888, 4333, 5777, 6500, 7222, 8666, 0, 0 },
+		{ 1500, 3000, 4500, 6000, 9000, 12000, 13500, 15000, 18000,
+		  20000, 0 },
+		{ 3250, 6500, 9750, 13000, 19500, 26000, 29250, 32500, 39000,
+		  43333, 0 },
+	};
+
+	if (rate.guard)
+		return s1g_tpt_sgi[rate.bw][rate.rate] * 1000 * (rate.ss + 1);
+
+	return s1g_tpt_lgi[rate.bw][rate.rate] * 1000 * (rate.ss + 1);
+}
+
+static u32 calculate_throughput(struct mmrc_table *tb, u8 index)
+{
+	struct mmrc_rate rate = get_rate_row(tb, index);
+
+	/*
+	 * Avoid the overflow (observed for 8MHz MCS9 rate: 43333) by dividing
+	 * first before multiplying. Should not experience any loss of
+	 * precision as the throughput is already multiplied by 1000 in
+	 * mmrc_calculate_theoretical_throughput (returned as bits/sec)
+	 */
+	if (tb->table[rate.index].prob < 10)
+		return 0;
+	else if (rate.index == tb->best_tp.index && tb->interference_likely)
+		/*
+		 * Assist the best rate by increasing the probability by the
+		 * averaged variation
+		 */
+		return (mmrc_calculate_theoretical_throughput(rate) / 100) *
+		       (tb->table[rate.index].prob + tb->probability_variation);
+	else
+		return (mmrc_calculate_theoretical_throughput(rate) / 100) *
+		       tb->table[rate.index].prob;
+}
+
+static bool validate_rate(struct mmrc_table *tb, struct mmrc_rate *rate)
+{
+	if (rate->rate == MMRC_MCS10 &&
+	    (rate->bw != MMRC_BW_1MHZ || rate->ss != MMRC_SPATIAL_STREAM_1)) {
+		/*
+		 * 802.11ah does not support MCS10 with BW that is not 1MHz or
+		 * not 1 spatial stream.
+		 */
+		return false;
+	}
+
+	if (rate->rate == MMRC_MCS9 && rate->bw == MMRC_BW_2MHZ &&
+	    rate->ss != MMRC_SPATIAL_STREAM_3) {
+		/*
+		 * 802.11ah does not support MCS9 at 2MHz for 1, 2 or 4 spatial
+		 * streams
+		 */
+		return false;
+	}
+
+	if (rate->guard == MMRC_GUARD_SHORT &&
+	    !(tb->caps.sgi_per_bw & SGI_PER_BW(rate->bw)))
+		return false;
+
+	return true;
+}
+
+static u16 find_baseline_index(struct mmrc_table *tb)
+{
+	u32 i, theoretical_tp, min_theoretical_tp;
+	u16 row_count = rows_from_sta_caps(&tb->caps);
+	u16 min_theoretical_tp_index = 0;
+	struct mmrc_rate rate;
+
+	if (tb->caps.rates & MMRC_MASK(MMRC_MCS10))
+		return 0;
+
+	min_theoretical_tp =
+		mmrc_calculate_theoretical_throughput(get_rate_row(tb, 0));
+	for (i = 0; i < row_count; i++) {
+		rate = get_rate_row(tb, i);
+		if (!validate_rate(tb, &rate))
+			continue;
+
+		theoretical_tp = mmrc_calculate_theoretical_throughput(rate);
+		if (min_theoretical_tp > theoretical_tp) {
+			min_theoretical_tp = theoretical_tp;
+			min_theoretical_tp_index = rate.index;
+		}
+	}
+
+	return min_theoretical_tp_index;
+}
+
+/*
+ * Fill out the remaining rates to be used once the best rate is selected.
+ * Normally the retry rates are one MCS lower than the previous, however in
+ * unconverged mode we limit the 3 respective retry rates to MCS 4, 2 and 0
+ * respectively. The last retry rate is always MCS 0
+ */
+static void mmrc_fill_retry_rates(struct mmrc_table *tb)
+{
+	tb->second_tp = tb->best_tp;
+	if (tb->second_tp.rate != MMRC_MCS0) {
+		tb->second_tp.rate--;
+		if (tb->unconverged && tb->second_tp.rate > MMRC_MCS4)
+			tb->second_tp.rate = MMRC_MCS4;
+		rate_update_index(tb, &tb->second_tp);
+	} else if (tb->second_tp.bw > MMRC_BW_1MHZ) {
+		tb->second_tp.bw--;
+		rate_update_index(tb, &tb->second_tp);
+	}
+
+	tb->best_prob = tb->second_tp;
+	if (tb->best_prob.rate != MMRC_MCS0) {
+		tb->best_prob.rate--;
+		if (tb->unconverged && tb->best_prob.rate > MMRC_MCS2)
+			tb->best_prob.rate = MMRC_MCS2;
+		rate_update_index(tb, &tb->best_prob);
+	} else if (tb->best_prob.bw > MMRC_BW_1MHZ) {
+		tb->best_prob.bw--;
+		rate_update_index(tb, &tb->best_prob);
+	}
+
+	tb->baseline = tb->best_prob;
+	if (tb->baseline.rate != MMRC_MCS0) {
+		tb->baseline.rate = MMRC_MCS0;
+		rate_update_index(tb, &tb->baseline);
+	} else if (tb->baseline.bw > MMRC_BW_1MHZ) {
+		tb->baseline.bw--;
+		rate_update_index(tb, &tb->baseline);
+	}
+}
+
+/*
+ * Updates the mmrc_table with the appropriate rate priority based on the
+ * latest update statistics
+ */
+static void generate_table_priority(struct mmrc_table *tb, u32 new_stats)
+{
+	u16 i;
+	u16 best_row = tb->best_tp.index;
+	u16 prev_best_row = best_row;
+	u8 prev_best_rate = tb->best_tp.rate;
+	u16 second_best_row = tb->second_tp.index;
+	u32 best_tp = calculate_throughput(tb, best_row);
+	u32 second_best_tp = calculate_throughput(tb, second_best_row);
+	u32 last_nonzero_prob = 0;
+	struct mmrc_rate tmp;
+	u32 tmp_tp;
+
+	/* Use fixed rate if set */
+	if (tb->fixed_rate.rate != MMRC_MCS_UNUSED) {
+		tb->best_tp = tb->fixed_rate;
+		tb->second_tp = tb->fixed_rate;
+		tb->best_prob = tb->fixed_rate;
+		return;
+	}
+
+	for (i = 0; i < rows_from_sta_caps(&tb->caps); i++) {
+		tmp = get_rate_row(tb, i);
+		if (!validate_rate(tb, &tmp))
+			continue;
+
+		if (tb->table[tmp.index].evidence == 0)
+			continue;
+
+		/*
+		 * Besides better throughput, also consider this rate better if
+		 * lower rates had worse probability. That indicates the rate
+		 * itself is not the problem. Only do the probability check for
+		 * rates up to the previous best rate.
+		 */
+		tmp_tp = calculate_throughput(tb, tmp.index);
+
+		if (tmp_tp > best_tp ||
+		    (tb->table[tmp.index].max_throughput <=
+			     tb->table[prev_best_row].max_throughput &&
+		     tb->table[tmp.index].prob >=
+			     PROBABILITY_DIP_RECOVERY_MIN &&
+		     tb->table[tmp.index].prob >
+			     tb->table[last_nonzero_prob].prob)) {
+			second_best_row = best_row;
+			second_best_tp = best_tp;
+
+			best_tp = tmp_tp;
+			best_row = tmp.index;
+		} else if (tmp_tp > second_best_tp && best_row != tmp.index) {
+			second_best_tp = tmp_tp;
+			second_best_row = tmp.index;
+		}
+
+		if (tb->table[tmp.index].prob >= PROBABILITY_DIP_MIN &&
+		    tb->table[tmp.index].max_throughput >=
+			    tb->table[last_nonzero_prob].max_throughput)
+			last_nonzero_prob = tmp.index;
+	}
+
+	/* Only update rates and stability when there are new statistics */
+	if (!new_stats)
+		return;
+
+	tb->best_tp = get_rate_row(tb, best_row);
+	if (best_tp == 0 && tb->best_tp.rate > MMRC_MCS0) {
+		/* Drop one rate, as the best throughput is zero */
+		tb->best_tp.rate--;
+		rate_update_index(tb, &tb->best_tp);
+	}
+	tb->second_tp = get_rate_row(tb, second_best_row);
+	mmrc_fill_retry_rates(tb);
+
+	if (tb->best_tp.rate > MMRC_MCS1 && prev_best_row == best_row) {
+		/* Increase the counter when the best rate is not changed */
+		tb->stability_cnt++;
+	} else if (tb->stability_cnt > STABILITY_BACKOFF_STEP) {
+		/* Back off the counter when there is a new best rate */
+		tb->stability_cnt -= STABILITY_BACKOFF_STEP;
+	} else {
+		tb->stability_cnt = 0;
+	}
+
+	if (prev_best_row != best_row) {
+		s8 latest_best_rate_diff = prev_best_rate - tb->best_tp.rate;
+		u8 total_abs_best_rate_diff =
+			abs(tb->best_rate_diff[0] + tb->best_rate_diff[1] +
+			    latest_best_rate_diff);
+
+		if (!tb->interference_likely) {
+			tb->probability_variation = 0;
+			if (!tb->unconverged &&
+			    tb->best_rate_cycle_count <=
+				    BEST_RATE_UNSTABLE_THRESHOLD &&
+			    total_abs_best_rate_diff >= 2) {
+				/*
+				 * Best rate has changed twice in a few cycles
+				 * and moved at least 2 MCSs from where it was
+				 * 3 best rate changes ago
+				 */
+				tb->unconverged = true;
+				tb->newly_unconverged = true;
+			}
+		}
+		if (tb->unconverged && !tb->newly_unconverged &&
+		    total_abs_best_rate_diff < 2) {
+			/*
+			 * Best rate has been relatively stable (not moved more
+			 * than 1 MCS after the last 3 rate changes), go back
+			 * to converged
+			 */
+			tb->unconverged = false;
+		}
+		tb->probability_variation_direction = 0;
+		tb->best_rate_cycle_count = 0;
+		tb->best_rate_diff[0] = tb->best_rate_diff[1];
+		tb->best_rate_diff[1] = latest_best_rate_diff;
+	} else {
+		tb->best_rate_cycle_count++;
+		if (tb->unconverged && !tb->newly_unconverged &&
+		    tb->best_rate_cycle_count >=
+			    BEST_RATE_CONVERGED_THRESHOLD) {
+			/*
+			 * Best rate has been stable for a while, go back to
+			 * converged
+			 */
+			tb->unconverged = false;
+		}
+	}
+
+	if (tb->newly_unconverged)
+		tb->newly_unconverged = false;
+}
+
+static u32 calculate_attempt_time(struct mmrc_rate *rate, size_t size)
+{
+	u32 time;
+
+	time = get_tx_time(rate);
+
+	if (size > DEFAULT_PACKET_SIZE_BYTES)
+		time = (time * ((size * 1000) / DEFAULT_PACKET_SIZE_BYTES)) /
+		       1000;
+	else
+		time = (time * 1000) /
+		       ((DEFAULT_PACKET_SIZE_BYTES * 1000) / size);
+
+	return time;
+}
+
+u32 mmrc_calculate_rate_tx_time(struct mmrc_rate *rate, size_t size)
+{
+	u8 i;
+	u32 total_time = 0;
+
+	for (i = 0; i < rate->attempts; i++)
+		total_time += calculate_attempt_time(rate, size);
+
+	return total_time;
+}
+
+/*
+ * Calculates the appropriate amount of additional attempts to make based on
+ * packet size and theoretical throughput.
+ */
+static void calculate_remaining_attempts(struct mmrc_table *tb,
+					 struct mmrc_rate_table *rate,
+					 s32 *rem_time, size_t size)
+{
+	size_t i;
+
+	if (*rem_time <= 0)
+		return;
+
+	for (i = 0; i < MMRC_MAX_CHAIN_LENGTH; i++) {
+		u32 attempt_time;
+		u32 attempt;
+
+		if (rate->rates[i].rate == MMRC_MCS_UNUSED)
+			break;
+
+		/*
+		 * The attempts for these rates were calculated in the initial
+		 * attempt allocation
+		 */
+		if (tb->table[rate->rates[i].index].prob < 20)
+			continue;
+
+		if (i == 0 && (calculate_throughput(tb, rate->rates[i].index) <
+			       calculate_throughput(tb, tb->best_prob.index)))
+			continue;
+
+		attempt_time = calculate_attempt_time(&rate->rates[i], size);
+		if (!attempt_time)
+			continue;
+
+		attempt = (*rem_time / tb->caps.max_rates) / attempt_time;
+		attempt += rate->rates[i].attempts;
+
+		rate->rates[i].attempts = MMRC_ATTEMPTS_TO_BITFIELD(
+			attempt > MMRC_MAX_CHAIN_ATTEMPTS ?
+				MMRC_MAX_CHAIN_ATTEMPTS :
+				attempt);
+	}
+}
+
+/* Allocate initial attempts to all rates in a rate table */
+static void allocate_initial_attempts(struct mmrc_rate_table *rate,
+				      s32 *rem_time, size_t size)
+{
+	u32 i;
+
+	for (i = 0; i < MMRC_MAX_CHAIN_LENGTH; i++) {
+		u32 attempt_time;
+
+		if (rate->rates[i].rate == MMRC_MCS_UNUSED)
+			break;
+
+		attempt_time = calculate_attempt_time(&rate->rates[i], size);
+
+		/*
+		 * if the time for a single attempt is very long, lets just
+		 * try once
+		 */
+		if (attempt_time > MAX_WINDOW_ATTEMPT_TIME) {
+			*rem_time -= attempt_time;
+			rate->rates[i].attempts = MMRC_ATTEMPTS_TO_BITFIELD(1);
+		} else {
+			*rem_time -= attempt_time * 2;
+			rate->rates[i].attempts = MMRC_ATTEMPTS_TO_BITFIELD(2);
+		}
+	}
+}
+
+void mmrc_get_rates(struct mmrc_table *tb, struct mmrc_rate_table *out,
+		    size_t size)
+{
+	u8 i;
+	u16 random_index;
+	struct mmrc_rate random;
+	struct mmrc_rate lookaround0 = tb->best_tp;
+	struct mmrc_rate lookaround1 = tb->second_tp;
+	bool is_lookaround;
+	int lookaround_index = -1;
+	int best_index = 0;
+	int random_tp = 0;
+	int best_tp;
+	int lookaround_fail_count;
+	bool try_current_lookaround = false;
+
+	s32 rem_time = RATE_WINDOW_MICROSECONDS;
+
+	memset(out, 0, sizeof(*out));
+
+	tb->lookaround_cnt = (tb->lookaround_cnt + 1) % tb->lookaround_wrap;
+	/*
+	 * Look around if the counter wraps or there has been no look around
+	 * for a number of rate control cycles.
+	 */
+	is_lookaround = (tb->fixed_rate.rate == MMRC_MCS_UNUSED) &&
+			((tb->lookaround_cnt == 0) ||
+			 ((tb->last_lookaround_cycle +
+			   LOOKAROUND_MAX_RC_CYCLES) <= tb->cycle_cnt));
+
+	/* Also skip sampling if we don't yet have data for our best rate */
+	if (tb->table[tb->best_tp.index].evidence == 0)
+		is_lookaround = false;
+
+	if (tb->lookaround_wrap != LOOKAROUND_RATE_STABLE) {
+		if (tb->stability_cnt >= tb->stability_cnt_threshold) {
+			tb->lookaround_wrap = LOOKAROUND_RATE_STABLE;
+			tb->stability_cnt_threshold =
+				STABILITY_CNT_THRESHOLD_STABLE;
+			tb->stability_cnt = STABILITY_CNT_THRESHOLD_STABLE * 2;
+			is_lookaround = false;
+		}
+	} else if (tb->stability_cnt < tb->stability_cnt_threshold) {
+		tb->stability_cnt_threshold = STABILITY_CNT_THRESHOLD_NORMAL;
+		tb->lookaround_wrap = LOOKAROUND_RATE_NORMAL;
+		tb->stability_cnt = 0;
+	}
+
+	/* Look around only when the fixed rate is not set */
+	if (is_lookaround) {
+		tb->total_lookaround++;
+		tb->forced_lookaround =
+			(tb->forced_lookaround + 1) % LOOKAROUND_RATE_NORMAL;
+		tb->last_lookaround_cycle = tb->cycle_cnt;
+
+		if (tb->current_lookaround_rate_attempts <
+		    LOOKAROUND_RATE_ATTEMPTS)
+			try_current_lookaround = true;
+
+		best_tp = calculate_throughput(tb, tb->best_tp.index);
+
+		for (lookaround_fail_count = 0;
+		     lookaround_fail_count < LOOKAROUND_FAIL_MAX;
+		     lookaround_fail_count++) {
+			if (try_current_lookaround) {
+				random_index =
+					tb->current_lookaround_rate_index;
+				try_current_lookaround = false;
+			} else {
+				random_index = get_random_u32_below(
+					rows_from_sta_caps(&tb->caps));
+			}
+			random = get_rate_row(tb, random_index);
+
+			if (!validate_rate(tb, &random))
+				continue;
+
+			if (random.rate == MMRC_MCS10)
+				continue;
+
+			if (tb->table[random_index].evidence > 0)
+				random_tp =
+					calculate_throughput(tb, random_index);
+			else
+				random_tp =
+					mmrc_calculate_theoretical_throughput(
+						random);
+
+			/*
+			 * Skip rates that can only be worse than the current
+			 * best
+			 */
+			if (random_tp <= best_tp)
+				continue;
+
+			/*
+			 * Force looking up the rate no more that one MCS.
+			 * It will avoid looking for rates with very low
+			 * success rate. In case of better environment
+			 * conditions MMRC will collect enough statistics to
+			 * climb up the rates one by one.
+			 */
+			if (random.rate > tb->best_tp.rate + 1 ||
+			    random.bw > tb->best_tp.bw + 1 ||
+			    (random.rate > tb->best_tp.rate &&
+			     random.bw > tb->best_tp.bw))
+				continue;
+
+			if (tb->current_lookaround_rate_index == random_index) {
+				tb->current_lookaround_rate_attempts++;
+			} else {
+				tb->current_lookaround_rate_attempts = 0;
+				tb->current_lookaround_rate_index =
+					random_index;
+			}
+
+			break;
+		}
+
+		if (lookaround_fail_count >= LOOKAROUND_FAIL_MAX) {
+			is_lookaround = false;
+			tb->current_lookaround_rate_index = tb->best_tp.index;
+		} else {
+			lookaround0 = random;
+			lookaround1 = tb->best_tp;
+			lookaround_index = 0;
+			best_index = 1;
+		}
+	}
+
+	if (tb->caps.max_rates == 1) {
+		out->rates[0] = (is_lookaround) ? lookaround0 : tb->best_tp;
+		out->rates[1].rate = MMRC_MCS_UNUSED;
+		out->rates[2].rate = MMRC_MCS_UNUSED;
+		out->rates[3].rate = MMRC_MCS_UNUSED;
+	} else if (tb->caps.max_rates == 2) {
+		out->rates[0] = (is_lookaround) ? lookaround0 : tb->best_tp;
+		out->rates[1] = (is_lookaround) ? lookaround1 : tb->best_prob;
+		out->rates[2].rate = MMRC_MCS_UNUSED;
+		out->rates[3].rate = MMRC_MCS_UNUSED;
+	} else if (tb->caps.max_rates == 3) {
+		out->rates[0] = (is_lookaround) ? lookaround0 : tb->best_tp;
+		out->rates[1] = (is_lookaround) ? lookaround1 : tb->second_tp;
+		out->rates[2] = tb->best_prob;
+		out->rates[3].rate = MMRC_MCS_UNUSED;
+	} else {
+		out->rates[0] = (is_lookaround) ? lookaround0 : tb->best_tp;
+		out->rates[1] = (is_lookaround) ? lookaround1 : tb->second_tp;
+		out->rates[2] = tb->best_prob;
+		out->rates[3] = tb->baseline;
+	}
+
+	/* For fallback rates, set RTS/CTS */
+	for (i = 1; i < MMRC_MAX_CHAIN_LENGTH; i++)
+		out->rates[i].flags |= MMRC_MASK(MMRC_FLAGS_CTS_RTS);
+
+	/* Allocate initial attempts for rate */
+	allocate_initial_attempts(out, &rem_time, size);
+
+	/* Calculate and allocate remaining attempts */
+	calculate_remaining_attempts(tb, out, &rem_time, size);
+
+	/* Enforce limits on each attempts */
+	for (i = 0; i < MMRC_MAX_CHAIN_LENGTH; i++) {
+		if (out->rates[i].rate != MMRC_MCS_UNUSED) {
+			out->rates[i].attempts =
+				out->rates[i].attempts == 0 ?
+					MMRC_ATTEMPTS_TO_BITFIELD(
+						MMRC_MIN_CHAIN_ATTEMPTS) :
+					out->rates[i].attempts;
+			out->rates[i].attempts =
+				out->rates[i].attempts >
+						MMRC_MAX_CHAIN_ATTEMPTS ?
+					MMRC_ATTEMPTS_TO_BITFIELD(
+						MMRC_MAX_CHAIN_ATTEMPTS) :
+					out->rates[i].attempts;
+			if (i == lookaround_index &&
+			    tb->lookaround_wrap != LOOKAROUND_RATE_INIT)
+				out->rates[i].attempts =
+					MMRC_ATTEMPTS_TO_BITFIELD(1);
+		}
+	}
+
+	/*
+	 * Give the best rate at least 2 attempts to keep peak throughput
+	 * unless it is too low
+	 */
+	if (out->rates[best_index].attempts == 1 &&
+	    out->rates[best_index].rate > MMRC_MCS1)
+		out->rates[best_index].attempts = MMRC_ATTEMPTS_TO_BITFIELD(2);
+	else if (out->rates[best_index].rate <= MMRC_MCS1)
+		out->rates[best_index].attempts = 1;
+}
+
+static u32 calc_ewma_average(u32 avg, u32 latest, u32 weight)
+{
+	WARN_ON_ONCE(!(weight <= 100));
+
+	if (avg == 0)
+		return latest;
+
+	return ((latest * (100 - weight)) + (avg * weight)) / 100;
+}
+
+static void mmrc_process_variation(struct mmrc_table *tb, u16 current_success,
+				   u32 index)
+{
+	u32 current_variation;
+
+	/*
+	 * Only process probability variation for the best rate. It is likely
+	 * the only rate to have enough data to see the variation and its
+	 * statistics are more affected because they are usually collected over
+	 * the full period.
+	 */
+	if (index != tb->best_tp.index)
+		return;
+
+	if (current_success == 0) {
+		if (!tb->unconverged) {
+			/*
+			 * Best rate is failing completely, go to unconverged
+			 * mode
+			 */
+			tb->unconverged = true;
+			tb->newly_unconverged = true;
+		}
+		return;
+	}
+
+	if (tb->table[index].prob == 0)
+		return;
+
+	/* Don't process variation while converging after association */
+	if (tb->lookaround_wrap == LOOKAROUND_RATE_INIT)
+		return;
+
+	current_variation = abs(current_success - tb->table[index].prob);
+
+	/* Calculate the EWMA of the probability variation */
+	tb->probability_variation = calc_ewma_average(
+		tb->probability_variation, current_variation, VARIATION_EWMA);
+
+	/*
+	 * Process the variation direction to distinguish converged and
+	 * unconverged scenarios
+	 */
+	if (tb->probability_variation >= MODERATE_VARIATION_THRESHOLD ||
+	    tb->interference_likely) {
+		if ((current_success - tb->table[index].prob) *
+			    tb->probability_variation_direction <
+		    0)
+			tb->probability_variation_direction = 0;
+		else if (current_success > tb->table[index].prob)
+			tb->probability_variation_direction =
+				min(tb->probability_variation_direction + 1,
+				    MAX_VARIATION_DIRECTION);
+		else if (current_success < tb->table[index].prob)
+			tb->probability_variation_direction =
+				max(tb->probability_variation_direction - 1,
+				    -MAX_VARIATION_DIRECTION);
+	}
+
+	if (tb->best_rate_cycle_count > VARIATION_DIRECTION_THRESHOLD &&
+	    tb->probability_variation >= SIGNIFICANT_VARIATION_THRESHOLD) {
+		/*
+		 * Only enter interference mode if the best rate is stable for
+		 * enough cycles to determine the direction is random and not
+		 * in one direction only
+		 */
+		if (abs(tb->probability_variation_direction) <=
+			    VARIATION_DIRECTION_THRESHOLD &&
+		    !tb->interference_likely) {
+			tb->interference_likely = true;
+		}
+	} else if (tb->interference_likely &&
+		   (tb->probability_variation <= MINOR_VARIATION_THRESHOLD ||
+		    abs(tb->probability_variation_direction) ==
+			    MAX_VARIATION_DIRECTION)) {
+		/*
+		 * Exit interference mode if the variability drops or the
+		 * direction stops being random
+		 */
+		tb->interference_likely = false;
+	}
+}
+
+void mmrc_update(struct mmrc_table *tb)
+{
+	u32 i;
+	u16 this_success;
+	u32 scale;
+	u32 scaled_ewma;
+	u32 new_stats = 0;
+	u32 attempts_for_stats;
+	u32 success_for_stats;
+	u32 min_stats;
+	u32 throughput;
+	u32 evidence_sent;
+
+	tb->cycle_cnt++;
+
+	/* Allow less minimum stats when converging */
+	if (tb->lookaround_wrap != LOOKAROUND_RATE_INIT)
+		min_stats = STATS_MIN_NORMAL;
+	else
+		min_stats = STATS_MIN_INIT;
+
+	for (i = 0; i < rows_from_sta_caps(&tb->caps); i++) {
+		/* This algorithm is keeping track of the amount of evidence,
+		 * being packets that have been recently sent at this rate.
+		 * This value is smoothed with an EWMA function over time and
+		 * used to update the probability of a rate succeeding
+		 * dynamically. This method allows MMRC to react timely if a
+		 * new rate is used that hasn't been used recently
+		 */
+
+		/* Necessary to prevent a divide by 0 */
+		if (tb->table[i].evidence == 0)
+			scale = 0;
+		else
+			scale = ((tb->table[i].evidence * 2) * 100) /
+				((tb->table[i].sent * EVIDENCE_SCALE) +
+				 tb->table[i].evidence);
+
+		/* Restrict scale to appropriate values */
+		if (scale > 100)
+			scale = 100;
+
+		scaled_ewma = scale * EWMA / 100;
+
+		/*
+		 * Only count new packets for evidence if we will process
+		 * them
+		 */
+		evidence_sent =
+			tb->table[i].sent >= min_stats ? tb->table[i].sent : 0;
+		tb->table[i].evidence = calc_ewma_average(
+			tb->table[i].evidence, evidence_sent * EVIDENCE_SCALE,
+			scaled_ewma);
+
+		if (tb->table[i].evidence > EVIDENCE_MAX)
+			tb->table[i].evidence = EVIDENCE_MAX;
+
+		/* Try to use statistics from acknowledged AMPDUs first */
+		attempts_for_stats = tb->table[i].back_mpdu_success +
+				     tb->table[i].back_mpdu_failure;
+		success_for_stats = tb->table[i].back_mpdu_success;
+
+		/*
+		 * Use the full statistics if rates are not converged or there
+		 * were no AMPDUs for this rate or the remaining attempts are
+		 * less than half of what we have from AMPDUs.
+		 */
+		if (!tb->table[i].have_sent_ampdus || tb->unconverged ||
+		    attempts_for_stats < AMPDU_STATS_MIN ||
+		    (tb->table[i].sent - attempts_for_stats <
+		     attempts_for_stats / 2)) {
+			attempts_for_stats = tb->table[i].sent;
+			success_for_stats = tb->table[i].sent_success;
+		}
+
+		if (attempts_for_stats >= min_stats ||
+		    (attempts_for_stats > 0 && tb->table[i].prob > 0)) {
+			new_stats = 1;
+			this_success =
+				(100 * success_for_stats) / attempts_for_stats;
+
+			if (scaled_ewma)
+				mmrc_process_variation(tb, this_success, i);
+
+			tb->table[i].prob = calc_ewma_average(
+				tb->table[i].prob, this_success, scaled_ewma);
+
+			/* Clear our sent statistics and update totals */
+			tb->table[i].total_sent += tb->table[i].sent;
+			tb->table[i].sent = 0;
+
+			tb->table[i].total_success += tb->table[i].sent_success;
+			tb->table[i].sent_success = 0;
+
+			tb->table[i].back_mpdu_failure = 0;
+			tb->table[i].back_mpdu_success = 0;
+			tb->table[i].have_sent_ampdus = false;
+		}
+
+		throughput = calculate_throughput(tb, i);
+		if (tb->table[i].max_throughput < throughput)
+			tb->table[i].max_throughput = throughput;
+
+		/*
+		 * Reset the running average windows if reached collector
+		 * limits
+		 */
+		if (tb->table[i].sum_throughput > (0xFFFFFFFF - throughput)) {
+			tb->table[i].sum_throughput /=
+				tb->table[i].avg_throughput_counter;
+			tb->table[i].avg_throughput_counter = 1;
+		}
+		/* Update the sum and counter so it will be possible later to
+		 * calculate the running average throughput
+		 */
+		tb->table[i].sum_throughput += throughput;
+		tb->table[i].avg_throughput_counter++;
+	}
+
+	generate_table_priority(tb, new_stats);
+
+	/*
+	 * Switch to faster lookaround mode if rates drop low at very low
+	 * bandwidth or we are in unconverged mode. Switching at low bandwidth
+	 * and rate is to help recover quickly from rates where we would need
+	 * to fragment standard MTU size packets.
+	 */
+	if (tb->lookaround_wrap != LOOKAROUND_RATE_INIT &&
+	    (tb->unconverged || (tb->best_tp.bw == MMRC_BW_1MHZ &&
+				 tb->best_tp.rate <= MMRC_MCS2))) {
+		tb->lookaround_cnt = 0;
+		tb->lookaround_wrap = LOOKAROUND_RATE_INIT;
+		tb->stability_cnt_threshold = STABILITY_CNT_THRESHOLD_INIT;
+	}
+
+	/*
+	 * If it is unlikely we can do the lookaround attempts in two RC cycles
+	 * choose a new rate
+	 */
+	if (tb->current_lookaround_rate_attempts <=
+	    (LOOKAROUND_RATE_ATTEMPTS / 2))
+		tb->current_lookaround_rate_attempts = LOOKAROUND_RATE_ATTEMPTS;
+}
+
+void mmrc_feedback(struct mmrc_table *tb, struct mmrc_rate_table *rates,
+		   s32 retry_count, bool was_aggregated)
+{
+	s32 ind = retry_count;
+	u32 i;
+
+	for (i = 0; i < MMRC_MAX_CHAIN_LENGTH; i++) {
+		rate_update_index(tb, &rates->rates[i]);
+		tb->table[rates->rates[i].index].have_sent_ampdus |=
+			was_aggregated;
+
+		if ((s32)rates->rates[i].attempts < ind) {
+			ind = ind - rates->rates[i].attempts;
+			tb->table[rates->rates[i].index].sent +=
+				rates->rates[i].attempts;
+			if (was_aggregated) {
+				tb->table[rates->rates[i].index]
+					.back_mpdu_failure +=
+					rates->rates[i].attempts;
+			}
+		} else {
+			tb->table[rates->rates[i].index].sent += ind;
+			tb->table[rates->rates[i].index].sent_success += 1;
+			if (was_aggregated) {
+				tb->table[rates->rates[i].index]
+					.back_mpdu_success += 1;
+				tb->table[rates->rates[i].index]
+					.back_mpdu_failure +=
+					ind > 1 ? ind - 1 : 0;
+			}
+			return;
+		}
+	}
+}
+
+/*
+ * Chooses a reasonable starting rate based on range (gathered from
+ * RSSI measurements) or bandwidth. Then fills out the 3 retry rates
+ * so a full set of rates is available.
+ */
+static void mmrc_init_rates(struct mmrc_table *tb, s8 rssi)
+{
+	tb->best_tp.bw = MMRC_MAX_BW(tb->caps.bandwidth);
+	if (tb->caps.sgi_per_bw & SGI_PER_BW(tb->best_tp.bw))
+		tb->best_tp.guard = MMRC_GUARD_TO_BITFIELD(MMRC_GUARD_SHORT);
+	else
+		tb->best_tp.guard = MMRC_GUARD_TO_BITFIELD(MMRC_GUARD_LONG);
+	tb->best_tp.rate = MMRC_RATE_TO_BITFIELD(MMRC_MCS0);
+
+	if (rssi >= MMRC_SHORT_RANGE_RSSI_LIMIT)
+		tb->best_tp.rate = MMRC_RATE_TO_BITFIELD(MMRC_MCS7);
+	else if (rssi < MMRC_SHORT_RANGE_RSSI_LIMIT &&
+		 rssi >= MMRC_MID_RANGE_RSSI_LIMIT)
+		tb->best_tp.rate = MMRC_RATE_TO_BITFIELD(MMRC_MCS3);
+	else if (tb->best_tp.bw == MMRC_BW_1MHZ ||
+		 tb->best_tp.bw == MMRC_BW_2MHZ)
+		/*
+		 * To compensate for slow feedback when running with 1 and 2
+		 * MHz bandwidth, we start from MCS3 which will correspond to
+		 * reasonable feedback and will avoid resetting the rate table
+		 * evidence.
+		 */
+		tb->best_tp.rate = MMRC_RATE_TO_BITFIELD(MMRC_MCS3);
+
+	tb->best_tp.ss = MMRC_SS_TO_BITFIELD(MMRC_SPATIAL_STREAM_1);
+	rate_update_index(tb, &tb->best_tp);
+	/* Init every rate in case they are needed to set the retry rates */
+	tb->second_tp = tb->best_tp;
+	tb->best_prob = tb->best_tp;
+	tb->baseline = tb->best_tp;
+	mmrc_fill_retry_rates(tb);
+}
+
+void mmrc_sta_init(struct mmrc_table *tb, struct mmrc_sta_capabilities *caps,
+		   s8 rssi)
+{
+	u32 i;
+	u16 row_count = rows_from_sta_caps(caps);
+
+	memset(tb, 0, mmrc_memory_required_for_caps(caps));
+	memcpy(&tb->caps, caps, sizeof(tb->caps));
+
+	for (i = 0; i < row_count; i++) {
+		tb->table[i].prob = RATE_INIT_PROBABILITY;
+		tb->table[i].evidence = 0;
+		tb->table[i].sum_throughput = 0;
+		tb->table[i].avg_throughput_counter = 0;
+		tb->table[i].max_throughput = 0;
+	}
+
+	tb->fixed_rate.rate = MMRC_MCS_UNUSED;
+	tb->cycle_cnt = 0;
+	tb->last_lookaround_cycle = 0;
+	tb->lookaround_cnt = 0;
+	tb->lookaround_wrap = LOOKAROUND_RATE_INIT;
+	tb->unconverged = true;
+	tb->newly_unconverged = true;
+	tb->stability_cnt_threshold = STABILITY_CNT_THRESHOLD_INIT;
+	tb->baseline = get_rate_row(tb, find_baseline_index(tb));
+	mmrc_init_rates(tb, rssi);
+}
+
+bool mmrc_set_fixed_rate(struct mmrc_table *tb, struct mmrc_rate fixed_rate)
+{
+	bool caps_support_rate = true;
+
+	/* Do not accept rate which does not support the STA capabilities */
+	if ((MMRC_MASK(fixed_rate.rate) & tb->caps.rates) == 0 ||
+	    (MMRC_MASK(fixed_rate.bw) & tb->caps.bandwidth) == 0 ||
+	    (MMRC_MASK(fixed_rate.ss) & tb->caps.spatial_streams) == 0 ||
+	    (MMRC_MASK(fixed_rate.guard) & tb->caps.guard) == 0)
+		caps_support_rate = false;
+
+	if (validate_rate(tb, &fixed_rate) && caps_support_rate) {
+		tb->fixed_rate = fixed_rate;
+		rate_update_index(tb, &tb->fixed_rate);
+		return true;
+	}
+
+	return false;
+}
-- 
2.43.0