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@xxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Huehn <thomas.huehn@xxxxxxxxxxxxxxxx>
Signed-off-by: Jonas Jelonek <jelonek.jonas@xxxxxxxxx>
---
drivers/net/wireless/ath/ath5k/base.c | 44 +++++++++++++++++++++++++--
1 file changed, 42 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index cef17f33c69e..647b3b76495c 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,
@@ -753,8 +790,11 @@ 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 (!ath5k_merge_ratetbl((control) ? control->sta : NULL, bf, info)) {
+ ieee80211_get_tx_rates(info->control.vif,
+ (control) ? control->sta : NULL, skb, bf->rates,
+ ARRAY_SIZE(bf->rates));
+ }
rate = ath5k_get_rate(ah->hw, info, bf, 0);
--
2.30.2
