[openwrt/openwrt] mac80211: backport minstrel_ht fix for legacy rates

[LEDE Commits]

nbd pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/5d5afd51772c9a992cb6bb9e0a9dce6feaa3fdef

commit 5d5afd51772c9a992cb6bb9e0a9dce6feaa3fdef
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Tue Apr 12 09:32:34 2022 +0200

    mac80211: backport minstrel_ht fix for legacy rates
    
    Fixes OFDM rates on 5 GHz
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 ...nstrel_ht-fix-where-rate-stats-are-stored.patch | 61 ++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/package/kernel/mac80211/patches/subsys/329-mac80211-minstrel_ht-fix-where-rate-stats-are-stored.patch b/package/kernel/mac80211/patches/subsys/329-mac80211-minstrel_ht-fix-where-rate-stats-are-stored.patch
new file mode 100644
index 0000000000..d7832acce5
--- /dev/null
+++ b/package/kernel/mac80211/patches/subsys/329-mac80211-minstrel_ht-fix-where-rate-stats-are-stored.patch
@@ -0,0 +1,61 @@
+From: Peter Seiderer <ps.report at gmx.net>
+Date: Mon, 4 Apr 2022 18:54:14 +0200
+Subject: [PATCH] mac80211: minstrel_ht: fix where rate stats are stored (fixes
+ debugfs output)
+
+Using an ath9k card the debugfs output of minstrel_ht looks like the following
+(note the zero values for the first four rates sum-of success/attempts):
+
+             best    ____________rate__________    ____statistics___    _____last____    ______sum-of________
+mode guard #  rate   [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]
+OFDM       1    DP     6.0M  272    1640     5.2       3.1      53.8       3     0 0             0   0
+OFDM       1   C       9.0M  273    1104     7.7       4.6      53.8       4     0 0             0   0
+OFDM       1  B       12.0M  274     836    10.0       6.0      53.8       4     0 0             0   0
+OFDM       1 A    S   18.0M  275     568    14.3       8.5      53.8       5     0 0             0   0
+OFDM       1      S   24.0M  276     436    18.1       0.0       0.0       5     0 1            80   1778
+OFDM       1          36.0M  277     300    24.9       0.0       0.0       0     0 1             0   107
+OFDM       1      S   48.0M  278     236    30.4       0.0       0.0       0     0 0             0   75
+OFDM       1          54.0M  279     212    33.0       0.0       0.0       0     0 0             0   72
+
+Total packet count::    ideal 16582      lookaround 885
+Average # of aggregated frames per A-MPDU: 1.0
+
+Debugging showed that the rate statistics for the first four rates where
+stored in the MINSTREL_CCK_GROUP instead of the MINSTREL_OFDM_GROUP because
+in minstrel_ht_get_stats() the supported check was not honoured as done in
+various other places, e.g net/mac80211/rc80211_minstrel_ht_debugfs.c:
+
+ 74                 if (!(mi->supported[i] & BIT(j)))
+ 75                         continue;
+
+With the patch applied the output looks good:
+
+              best    ____________rate__________    ____statistics___    _____last____    ______sum-of________
+mode guard #  rate   [name   idx airtime  max_tp]  [avg(tp) avg(prob)]  [retry|suc|att]  [#success | #attempts]
+OFDM       1    D      6.0M  272    1640     5.2       5.2     100.0       3     0 0             1   1
+OFDM       1   C       9.0M  273    1104     7.7       7.7     100.0       4     0 0            38   38
+OFDM       1  B       12.0M  274     836    10.0       9.9      89.5       4     2 2           372   395
+OFDM       1 A   P    18.0M  275     568    14.3      14.3      97.2       5    52 53         6956   7181
+OFDM       1      S   24.0M  276     436    18.1       0.0       0.0       0     0 1             6   163
+OFDM       1          36.0M  277     300    24.9       0.0       0.0       0     0 1             0   35
+OFDM       1      S   48.0M  278     236    30.4       0.0       0.0       0     0 0             0   38
+OFDM       1      S   54.0M  279     212    33.0       0.0       0.0       0     0 0             0   38
+
+Total packet count::    ideal 7097      lookaround 287
+Average # of aggregated frames per A-MPDU: 1.0
+
+Signed-off-by: Peter Seiderer <ps.report at gmx.net>
+---
+
+--- a/net/mac80211/rc80211_minstrel_ht.c
++++ b/net/mac80211/rc80211_minstrel_ht.c
+@@ -364,6 +364,9 @@ minstrel_ht_get_stats(struct minstrel_pr
+ 
+ 	group = MINSTREL_CCK_GROUP;
+ 	for (idx = 0; idx < ARRAY_SIZE(mp->cck_rates); idx++) {
++		if (!(mi->supported[group] & BIT(idx)))
++			continue;
++
+ 		if (rate->idx != mp->cck_rates[idx])
+ 			continue;
+