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ath5k: switch to rate table based lookup

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Switching from legacy usage of ieee80211_get_tx_rates() lookup to direct
rate table lookup in struct ieee80211_sta->rates.

The current rate control API allows drivers to directly get rates from
ieee80211_sta->rates. ath5k is currently one of the legacy drivers that
perform translation/merge with the internal rate table via
ieee80211_get_tx_rates provided by rate control API.
For our upcoming changes to rate control API and the implementation of
transmit power control, this patch changes the behaviour. The call to
ieee80211_get_tx_rates and subsequent calls are also avoided. ath5k now
directly reads rates from sta->rates into its internal rate table. Cause
ath5k does not rely on the rate array in SKB->CB, this is not considered
anymore except for the first entry (used for probing).

Tested this on a PCEngines ALIX with CMP9-GP miniPCI wifi card (Atheros
AR5213A). Generated traffic between AP and multiple STAs before and
after applying the patch and simultaneously measured throughput and
captured rc_stats. Comparison resulted in same rate selection and no
performance loss between both runs.

Co-developed-by: Thomas Huehn <thomas.huehn@hs-nordhausen.de>
Signed-off-by: Thomas Huehn <thomas.huehn@hs-nordhausen.de>
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20211215215042.637-1-jelonek.jonas@gmail.com
This commit is contained in:
Jonas Jelonek
2021-12-17 20:27:20 +02:00
committed by Kalle Valo
parent f75c1d55ec
commit a5d862da91
1 changed files with 48 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/net/wireless/ath/ath5k/base.c
+48 -2
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@@ -727,6 +727,43 @@ ath5k_get_rate_hw_value(const struct ieee80211_hw *hw,
return hw_rate;
}
static bool ath5k_merge_ratetbl(struct ieee80211_sta *sta,
struct ath5k_buf *bf,
struct ieee80211_tx_info *tx_info)
{
struct ieee80211_sta_rates *ratetbl;
u8 i;
if (!sta)
return false;
ratetbl = rcu_dereference(sta->rates);
if (!ratetbl)
return false;
if (tx_info->control.rates[0].idx < 0 ||
tx_info->control.rates[0].count == 0)
{
i = 0;
} else {
bf->rates[0] = tx_info->control.rates[0];
i = 1;
}
for ( ; i < IEEE80211_TX_MAX_RATES; i++) {
bf->rates[i].idx = ratetbl->rate[i].idx;
bf->rates[i].flags = ratetbl->rate[i].flags;
if (tx_info->control.use_rts)
bf->rates[i].count = ratetbl->rate[i].count_rts;
else if (tx_info->control.use_cts_prot)
bf->rates[i].count = ratetbl->rate[i].count_cts;
else
bf->rates[i].count = ratetbl->rate[i].count;
}
return true;
}
static int
ath5k_txbuf_setup(struct ath5k_hw *ah, struct ath5k_buf *bf,
struct ath5k_txq *txq, int padsize,
@@ -737,6 +774,7 @@ ath5k_txbuf_setup(struct ath5k_hw *ah, struct ath5k_buf *bf,
struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
unsigned int pktlen, flags, keyidx = AR5K_TXKEYIX_INVALID;
struct ieee80211_rate *rate;
struct ieee80211_sta *sta;
unsigned int mrr_rate[3], mrr_tries[3];
int i, ret;
u16 hw_rate;
@@ -753,8 +791,16 @@ ath5k_txbuf_setup(struct ath5k_hw *ah, struct ath5k_buf *bf,
if (dma_mapping_error(ah->dev, bf->skbaddr))
return -ENOSPC;
ieee80211_get_tx_rates(info->control.vif, (control) ? control->sta : NULL, skb, bf->rates,
ARRAY_SIZE(bf->rates));
if (control)
sta = control->sta;
else
sta = NULL;
if (!ath5k_merge_ratetbl(sta, bf, info)) {
ieee80211_get_tx_rates(info->control.vif,
sta, skb, bf->rates,
ARRAY_SIZE(bf->rates));
}
rate = ath5k_get_rate(ah->hw, info, bf, 0);