mac80211: initialize last_rate for S1G STAs

last_rate is initialized to zero by sta_info_alloc(), but
this indicates legacy bitrate for the last TX rate (and
invalid for the last RX rate). To avoid a warning when
decoding the last rate as legacy (before a data frame
has been sent), initialize them as S1G MCS.

Signed-off-by: Thomas Pedersen <thomas@adapt-ip.com>
Link: https://lore.kernel.org/r/20201005164522.18069-2-thomas@adapt-ip.com
[rename to ieee80211_s1g_sta_rate_init(), seems more appropriate]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/Makefile

@@ -13,6 +13,7 @@ mac80211-y := \
 	ht.o agg-tx.o agg-rx.o \
 	vht.o \
 	he.o \
+	s1g.o \
 	ibss.o \
 	iface.o \
 	rate.o \

net/mac80211/ieee80211_i.h

@@ -1928,6 +1928,9 @@ void
 ieee80211_he_op_ie_to_bss_conf(struct ieee80211_vif *vif,
 			const struct ieee80211_he_operation *he_op_ie_elem);
 
+/* S1G */
+void ieee80211_s1g_sta_rate_init(struct sta_info *sta);
+
 /* Spectrum management */
 void ieee80211_process_measurement_req(struct ieee80211_sub_if_data *sdata,
 				       struct ieee80211_mgmt *mgmt,

net/mac80211/mlme.c

@@ -5190,8 +5190,10 @@ static int ieee80211_prep_connection(struct ieee80211_sub_if_data *sdata,
 		int shift = ieee80211_vif_get_shift(&sdata->vif);
 
 		/* TODO: S1G Basic Rate Set is expressed elsewhere */
-		if (cbss->channel->band == NL80211_BAND_S1GHZ)
+		if (cbss->channel->band == NL80211_BAND_S1GHZ) {
+			ieee80211_s1g_sta_rate_init(new_sta);
 			goto skip_rates;
+		}
 
 		ieee80211_get_rates(sband, bss->supp_rates,
 				    bss->supp_rates_len,

net/mac80211/rate.c

@@ -53,6 +53,7 @@ void rate_control_rate_init(struct sta_info *sta)
 
 	/* TODO: check for minstrel_s1g ? */
 	if (sband->band == NL80211_BAND_S1GHZ) {
+		ieee80211_s1g_sta_rate_init(sta);
 		rcu_read_unlock();
 		return;
 	}

net/mac80211/s1g.c

@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * S1G handling
+ * Copyright(c) 2020 Adapt-IP
+ */
+#include <linux/ieee80211.h>
+#include <net/mac80211.h>
+#include "ieee80211_i.h"
+
+void ieee80211_s1g_sta_rate_init(struct sta_info *sta)
+{
+	/* avoid indicating legacy bitrates for S1G STAs */
+	sta->tx_stats.last_rate.flags |= IEEE80211_TX_RC_S1G_MCS;
+	sta->rx_stats.last_rate =
+			STA_STATS_FIELD(TYPE, STA_STATS_RATE_TYPE_S1G);
+}

net/mac80211/sta_info.h

@@ -823,6 +823,7 @@ enum sta_stats_type {
 	STA_STATS_RATE_TYPE_HT,
 	STA_STATS_RATE_TYPE_VHT,
 	STA_STATS_RATE_TYPE_HE,
+	STA_STATS_RATE_TYPE_S1G,
 };
 
 #define STA_STATS_FIELD_HT_MCS		GENMASK( 7,  0)