From a5d862da91058a855ab00bf46b5383543bbf3979 Mon Sep 17 00:00:00 2001
From: Jonas Jelonek <jelonek.jonas@gmail.com>
Date: Fri, 17 Dec 2021 20:27:20 +0200
Subject: [PATCH] ath5k: switch to rate table based lookup
Git-commit: a5d862da91058a855ab00bf46b5383543bbf3979
Patch-mainline: v5.17-rc1
References: bsc#1206451
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
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/net/wireless/ath/ath5k/base.c | 50 +++++++++++++++++++++++++--
1 file changed, 48 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index cef17f33c69e..66d123f48085 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -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);
--
2.35.3