mac80211/minstrel_ht: add support for using CCK rates
When MCS rates start to get bad in 2.4 GHz because of long range or
strong interference, CCK rates can be a lot more robust.
This patch adds a pseudo MCS group containing CCK rates (long preamble
in the lower 4 slots, short preamble in the upper slots).
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
[make minstrel_ht_get_stats static]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
index 5bb316a..6e35dcd 100644
--- a/net/mac80211/rc80211_minstrel_ht.c
+++ b/net/mac80211/rc80211_minstrel_ht.c
@@ -1,5 +1,5 @@
/*
- * Copyright (C) 2010 Felix Fietkau <nbd@openwrt.org>
+ * Copyright (C) 2010-2013 Felix Fietkau <nbd@openwrt.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
@@ -63,6 +63,30 @@
} \
}
+#define CCK_DURATION(_bitrate, _short, _len) \
+ (10 /* SIFS */ + \
+ (_short ? 72 + 24 : 144 + 48 ) + \
+ (8 * (_len + 4) * 10) / (_bitrate))
+
+#define CCK_ACK_DURATION(_bitrate, _short) \
+ (CCK_DURATION((_bitrate > 10 ? 20 : 10), false, 60) + \
+ CCK_DURATION(_bitrate, _short, AVG_PKT_SIZE))
+
+#define CCK_DURATION_LIST(_short) \
+ CCK_ACK_DURATION(10, _short), \
+ CCK_ACK_DURATION(20, _short), \
+ CCK_ACK_DURATION(55, _short), \
+ CCK_ACK_DURATION(110, _short)
+
+#define CCK_GROUP \
+ [MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS] = { \
+ .streams = 0, \
+ .duration = { \
+ CCK_DURATION_LIST(false), \
+ CCK_DURATION_LIST(true) \
+ } \
+ }
+
/*
* To enable sufficiently targeted rate sampling, MCS rates are divided into
* groups, based on the number of streams and flags (HT40, SGI) that they
@@ -95,8 +119,13 @@
#if MINSTREL_MAX_STREAMS >= 3
MCS_GROUP(3, 1, 1),
#endif
+
+ /* must be last */
+ CCK_GROUP
};
+#define MINSTREL_CCK_GROUP (ARRAY_SIZE(minstrel_mcs_groups) - 1)
+
static u8 sample_table[SAMPLE_COLUMNS][MCS_GROUP_RATES];
/*
@@ -119,6 +148,29 @@
!!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
}
+static struct minstrel_rate_stats *
+minstrel_ht_get_stats(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+ struct ieee80211_tx_rate *rate)
+{
+ int group, idx;
+
+ if (rate->flags & IEEE80211_TX_RC_MCS) {
+ group = minstrel_ht_get_group_idx(rate);
+ idx = rate->idx % MCS_GROUP_RATES;
+ } else {
+ group = MINSTREL_CCK_GROUP;
+
+ for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++)
+ if (rate->idx == mp->cck_rates[idx])
+ break;
+
+ /* short preamble */
+ if (!(mi->groups[group].supported & BIT(idx)))
+ idx += 4;
+ }
+ return &mi->groups[group].rates[idx];
+}
+
static inline struct minstrel_rate_stats *
minstrel_get_ratestats(struct minstrel_ht_sta *mi, int index)
{
@@ -159,7 +211,7 @@
minstrel_ht_calc_tp(struct minstrel_ht_sta *mi, int group, int rate)
{
struct minstrel_rate_stats *mr;
- unsigned int usecs;
+ unsigned int usecs = 0;
mr = &mi->groups[group].rates[rate];
@@ -168,7 +220,9 @@
return;
}
- usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
+ if (group != MINSTREL_CCK_GROUP)
+ usecs = mi->overhead / MINSTREL_TRUNC(mi->avg_ampdu_len);
+
usecs += minstrel_mcs_groups[group].duration[rate];
mr->cur_tp = MINSTREL_TRUNC((1000000 / usecs) * mr->probability);
}
@@ -293,7 +347,7 @@
}
static bool
-minstrel_ht_txstat_valid(struct ieee80211_tx_rate *rate)
+minstrel_ht_txstat_valid(struct minstrel_priv *mp, struct ieee80211_tx_rate *rate)
{
if (rate->idx < 0)
return false;
@@ -301,7 +355,13 @@
if (!rate->count)
return false;
- return !!(rate->flags & IEEE80211_TX_RC_MCS);
+ if (rate->flags & IEEE80211_TX_RC_MCS)
+ return true;
+
+ return rate->idx == mp->cck_rates[0] ||
+ rate->idx == mp->cck_rates[1] ||
+ rate->idx == mp->cck_rates[2] ||
+ rate->idx == mp->cck_rates[3];
}
static void
@@ -386,7 +446,6 @@
struct minstrel_rate_stats *rate, *rate2;
struct minstrel_priv *mp = priv;
bool last;
- int group;
int i;
if (!msp->is_ht)
@@ -415,13 +474,12 @@
if (info->flags & IEEE80211_TX_CTL_RATE_CTRL_PROBE)
mi->sample_packets += info->status.ampdu_len;
- last = !minstrel_ht_txstat_valid(&ar[0]);
+ last = !minstrel_ht_txstat_valid(mp, &ar[0]);
for (i = 0; !last; i++) {
last = (i == IEEE80211_TX_MAX_RATES - 1) ||
- !minstrel_ht_txstat_valid(&ar[i + 1]);
+ !minstrel_ht_txstat_valid(mp, &ar[i + 1]);
- group = minstrel_ht_get_group_idx(&ar[i]);
- rate = &mi->groups[group].rates[ar[i].idx % 8];
+ rate = minstrel_ht_get_stats(mp, mi, &ar[i]);
if (last)
rate->success += info->status.ampdu_ack_len;
@@ -447,7 +505,8 @@
if (time_after(jiffies, mi->stats_update + (mp->update_interval / 2 * HZ) / 1000)) {
minstrel_ht_update_stats(mp, mi);
- if (!(info->flags & IEEE80211_TX_CTL_AMPDU))
+ if (!(info->flags & IEEE80211_TX_CTL_AMPDU) &&
+ mi->max_prob_rate / MCS_GROUP_RATES != MINSTREL_CCK_GROUP)
minstrel_aggr_check(sta, skb);
}
}
@@ -463,6 +522,7 @@
unsigned int ctime = 0;
unsigned int t_slot = 9; /* FIXME */
unsigned int ampdu_len = MINSTREL_TRUNC(mi->avg_ampdu_len);
+ unsigned int overhead = 0, overhead_rtscts = 0;
mr = minstrel_get_ratestats(mi, index);
if (mr->probability < MINSTREL_FRAC(1, 10)) {
@@ -484,9 +544,14 @@
ctime += (t_slot * cw) >> 1;
cw = min((cw << 1) | 1, mp->cw_max);
+ if (index / MCS_GROUP_RATES != MINSTREL_CCK_GROUP) {
+ overhead = mi->overhead;
+ overhead_rtscts = mi->overhead_rtscts;
+ }
+
/* Total TX time for data and Contention after first 2 tries */
- tx_time = ctime + 2 * (mi->overhead + tx_time_data);
- tx_time_rtscts = ctime + 2 * (mi->overhead_rtscts + tx_time_data);
+ tx_time = ctime + 2 * (overhead + tx_time_data);
+ tx_time_rtscts = ctime + 2 * (overhead_rtscts + tx_time_data);
/* See how many more tries we can fit inside segment size */
do {
@@ -495,8 +560,8 @@
cw = min((cw << 1) | 1, mp->cw_max);
/* Total TX time after this try */
- tx_time += ctime + mi->overhead + tx_time_data;
- tx_time_rtscts += ctime + mi->overhead_rtscts + tx_time_data;
+ tx_time += ctime + overhead + tx_time_data;
+ tx_time_rtscts += ctime + overhead_rtscts + tx_time_data;
if (tx_time_rtscts < mp->segment_size)
mr->retry_count_rtscts++;
@@ -526,9 +591,16 @@
else
rate->count = mr->retry_count;
- rate->flags = IEEE80211_TX_RC_MCS | group->flags;
+ rate->flags = 0;
if (rtscts)
rate->flags |= IEEE80211_TX_RC_USE_RTS_CTS;
+
+ if (index / MCS_GROUP_RATES == MINSTREL_CCK_GROUP) {
+ rate->idx = mp->cck_rates[index % ARRAY_SIZE(mp->cck_rates)];
+ return;
+ }
+
+ rate->flags |= IEEE80211_TX_RC_MCS | group->flags;
rate->idx = index % MCS_GROUP_RATES + (group->streams - 1) * MCS_GROUP_RATES;
}
@@ -592,6 +664,22 @@
}
static void
+minstrel_ht_check_cck_shortpreamble(struct minstrel_priv *mp,
+ struct minstrel_ht_sta *mi, bool val)
+{
+ u8 supported = mi->groups[MINSTREL_CCK_GROUP].supported;
+
+ if (!supported || !mi->cck_supported_short)
+ return;
+
+ if (supported & (mi->cck_supported_short << (val * 4)))
+ return;
+
+ supported ^= mi->cck_supported_short | (mi->cck_supported_short << 4);
+ mi->groups[MINSTREL_CCK_GROUP].supported = supported;
+}
+
+static void
minstrel_ht_get_rate(void *priv, struct ieee80211_sta *sta, void *priv_sta,
struct ieee80211_tx_rate_control *txrc)
{
@@ -610,6 +698,7 @@
return mac80211_minstrel.get_rate(priv, sta, &msp->legacy, txrc);
info->flags |= mi->tx_flags;
+ minstrel_ht_check_cck_shortpreamble(mp, mi, txrc->short_preamble);
/* Don't use EAPOL frames for sampling on non-mrr hw */
if (mp->hw->max_rates == 1 &&
@@ -683,6 +772,30 @@
}
static void
+minstrel_ht_update_cck(struct minstrel_priv *mp, struct minstrel_ht_sta *mi,
+ struct ieee80211_supported_band *sband,
+ struct ieee80211_sta *sta)
+{
+ int i;
+
+ if (sband->band != IEEE80211_BAND_2GHZ)
+ return;
+
+ mi->cck_supported = 0;
+ mi->cck_supported_short = 0;
+ for (i = 0; i < 4; i++) {
+ if (!rate_supported(sta, sband->band, mp->cck_rates[i]))
+ continue;
+
+ mi->cck_supported |= BIT(i);
+ if (sband->bitrates[i].flags & IEEE80211_RATE_SHORT_PREAMBLE)
+ mi->cck_supported_short |= BIT(i);
+ }
+
+ mi->groups[MINSTREL_CCK_GROUP].supported = mi->cck_supported;
+}
+
+static void
minstrel_ht_update_caps(void *priv, struct ieee80211_supported_band *sband,
struct ieee80211_sta *sta, void *priv_sta)
{
@@ -702,7 +815,7 @@
goto use_legacy;
BUILD_BUG_ON(ARRAY_SIZE(minstrel_mcs_groups) !=
- MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS);
+ MINSTREL_MAX_STREAMS * MINSTREL_STREAM_GROUPS + 1);
msp->is_ht = true;
memset(mi, 0, sizeof(*mi));
@@ -738,6 +851,11 @@
u16 req = 0;
mi->groups[i].supported = 0;
+ if (i == MINSTREL_CCK_GROUP) {
+ minstrel_ht_update_cck(mp, mi, sband, sta);
+ continue;
+ }
+
if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_SHORT_GI) {
if (minstrel_mcs_groups[i].flags & IEEE80211_TX_RC_40_MHZ_WIDTH)
req |= IEEE80211_HT_CAP_SGI_40;