ath9k: fix dynack in IBSS mode

Currently, dynack was only tested upstream using AP/STA mode.
Testing it on IBSS, showed that late-ack detection was broken.

This is caused due to dynack using Association Request/Response
frames for late-ack detection, which IBSS does not use.
Also allowing Authentication frames here solves this.

A second issue also got fixed, which was also seen AP/STA mode:

When a station was added, the estimated value would be exponentially averaged
using 0 as a starting point.

This means that on larger distances, the ack timeout was still not high
enough before synchronizing would run out of late-ack's for estimation.

Fix this by using the initial estimated value as a baseline
and only start averaging in the following estimation rounds.

Test setup:
- 2x identical devices:  RB912UAG-5HPnD + 19dB sector
- IBSS
- 2x2 802.11an (ar9340), HT20, long GI
- RSSI's  -70 / -71
- Real distance: 23910 meter

Results (60s iperf runs):

Fixed coverage class 54 (up to 24300m):
* 21.5 Mbits/sec

Dynack:
* 28.9 Mbits/sec

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/package/kernel/mac80211/patches/ath/555-ath9k-dynack-check-da-enabled-first-in-sampling-rout.patch b/package/kernel/mac80211/patches/ath/555-ath9k-dynack-check-da-enabled-first-in-sampling-rout.patch
new file mode 100644
index 0000000000..cc5cdf9233
--- /dev/null
+++ b/package/kernel/mac80211/patches/ath/555-ath9k-dynack-check-da-enabled-first-in-sampling-rout.patch
@@ -0,0 +1,33 @@
+From: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
+Date: Fri, 2 Nov 2018 21:49:57 +0100
+Subject: [PATCH] ath9k: dynack: check da->enabled first in sampling
+ routines
+
+Check da->enabled flag first in ath_dynack_sample_tx_ts and
+ath_dynack_sample_ack_ts routines in order to avoid useless
+processing
+
+Tested-by: Koen Vandeputte <koen.vandeputte@ncentric.com>
+Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
+---
+
+--- a/drivers/net/wireless/ath/ath9k/dynack.c
++++ b/drivers/net/wireless/ath/ath9k/dynack.c
+@@ -178,7 +178,7 @@ void ath_dynack_sample_tx_ts(struct ath_
+ 	u32 dur = ts->duration;
+ 	u8 ridx;
+ 
+-	if ((info->flags & IEEE80211_TX_CTL_NO_ACK) || !da->enabled)
++	if (!da->enabled || (info->flags & IEEE80211_TX_CTL_NO_ACK))
+ 		return;
+ 
+ 	spin_lock_bh(&da->qlock);
+@@ -251,7 +251,7 @@ void ath_dynack_sample_ack_ts(struct ath
+ 	struct ath_common *common = ath9k_hw_common(ah);
+ 	struct ieee80211_hdr *hdr = (struct ieee80211_hdr *)skb->data;
+ 
+-	if (!ath_dynack_bssidmask(ah, hdr->addr1) || !da->enabled)
++	if (!da->enabled || !ath_dynack_bssidmask(ah, hdr->addr1))
+ 		return;
+ 
+ 	spin_lock_bh(&da->qlock);