On 2013-02-08 5:22 PM, Paul Stewart wrote:
> On Fri, Feb 8, 2013 at 4:38 AM, Felix Fietkau <nbd@xxxxxxxxxxx> wrote:
>>
>> 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@xxxxxxxxxxx>
>> ---
>> net/mac80211/rc80211_minstrel.c | 29 ++++++
>> net/mac80211/rc80211_minstrel.h | 2 +
>> net/mac80211/rc80211_minstrel_ht.c | 152 +++++++++++++++++++++++++----
>> net/mac80211/rc80211_minstrel_ht.h | 5 +-
>> net/mac80211/rc80211_minstrel_ht_debugfs.c | 109 +++++++++++++--------
>> 5 files changed, 237 insertions(+), 60 deletions(-)
>>
>> diff --git a/net/mac80211/rc80211_minstrel.c b/net/mac80211/rc80211_minstrel.c
>> index 8c5acdc..eea45a2 100644
>> --- a/net/mac80211/rc80211_minstrel.c
>> +++ b/net/mac80211/rc80211_minstrel.c
>> @@ -494,6 +494,33 @@ minstrel_free_sta(void *priv, struct ieee80211_sta *sta, void *priv_sta)
>> kfree(mi);
>> }
>>
>> +static void
>> +minstrel_init_cck_rates(struct minstrel_priv *mp)
>> +{
>> + static const int bitrates[4] = { 10, 20, 55, 110 };
>> + struct ieee80211_supported_band *sband;
>> + int i, j;
>> +
>> + sband = mp->hw->wiphy->bands[IEEE80211_BAND_2GHZ];
>> + if (!sband)
>> + return;
>> +
>> + for (i = 0, j = 0; i < sband->n_bitrates; i++) {
>> + struct ieee80211_rate *rate = &sband->bitrates[i];
>> +
>> + if (rate->flags & IEEE80211_RATE_ERP_G)
>> + continue;
>> +
>> + for (j = 0; j < ARRAY_SIZE(bitrates); j++) {
>> + if (rate->bitrate != bitrates[j])
>> + continue;
>> +
>> + mp->cck_rates[j] = i;
>> + break;
>> + }
>> + }
>> +}
>> +
>> static void *
>> minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
>> {
>> @@ -539,6 +566,8 @@ minstrel_alloc(struct ieee80211_hw *hw, struct dentry *debugfsdir)
>> S_IRUGO | S_IWUGO, debugfsdir, &mp->fixed_rate_idx);
>> #endif
>>
>> + minstrel_init_cck_rates(mp);
>> +
>> return mp;
>> }
>>
>> diff --git a/net/mac80211/rc80211_minstrel.h b/net/mac80211/rc80211_minstrel.h
>> index 5d278ec..5ecf757 100644
>> --- a/net/mac80211/rc80211_minstrel.h
>> +++ b/net/mac80211/rc80211_minstrel.h
>> @@ -79,6 +79,8 @@ struct minstrel_priv {
>> unsigned int lookaround_rate;
>> unsigned int lookaround_rate_mrr;
>>
>> + u8 cck_rates[4];
>> +
>> #ifdef CONFIG_MAC80211_DEBUGFS
>> /*
>> * enable fixed rate processing per RC
>> diff --git a/net/mac80211/rc80211_minstrel_ht.c b/net/mac80211/rc80211_minstrel_ht.c
>> index 5bb316a..ba32416 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@xxxxxxxxxxx>
>> + * Copyright (C) 2010-2013 Felix Fietkau <nbd@xxxxxxxxxxx>
>> *
>> * 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 \
>> + { \
>> + .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 @@ const struct mcs_group minstrel_mcs_groups[] = {
>> #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 @@ minstrel_ht_get_group_idx(struct ieee80211_tx_rate *rate)
>> !!(rate->flags & IEEE80211_TX_RC_40_MHZ_WIDTH));
>> }
>>
>> +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 == idx)
>> + break;
> Either this if statement isn't doing what you think it does (perhaps
> you wanted rate->idx == mp->cck_rates[i]?) or this whole loop could be
> simplified with an if statement?
Right, thanks. By the way, I meant rate->idx == mp->cck_rates[idx].
It happened to work in my tests because both variants are equivalent on
ath9k, but that may not be true for other drivers. :)
- Felix
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