mac80211: minstrel_ht: add support for OFDM rates on non-HT clients

The legacy minstrel code is essentially unmaintained and receives only very
little testing. In order to bring the significant algorithm improvements from
minstrel_ht to legacy clients, this patch adds support for OFDM rates to
minstrel_ht and removes the fallback to the legacy codepath.
This also makes it work much better on hardware with rate selection constraints,
e.g. mt76.
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210115120242.89616-3-nbd@nbd.nameSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/rc80211_minstrel.h

@@ -152,6 +152,7 @@ struct minstrel_priv {
 	unsigned int lookaround_rate_mrr;
 
 	u8 cck_rates[4];
+	u8 ofdm_rates[NUM_NL80211_BANDS][8];
 
 #ifdef CONFIG_MAC80211_DEBUGFS
 	/*

net/mac80211/rc80211_minstrel_ht.h

@@ -18,14 +18,15 @@
 				 MINSTREL_HT_STREAM_GROUPS)
 #define MINSTREL_VHT_GROUPS_NB	(MINSTREL_MAX_STREAMS *		\
 				 MINSTREL_VHT_STREAM_GROUPS)
-#define MINSTREL_CCK_GROUPS_NB	1
+#define MINSTREL_LEGACY_GROUPS_NB	2
 #define MINSTREL_GROUPS_NB	(MINSTREL_HT_GROUPS_NB +	\
 				 MINSTREL_VHT_GROUPS_NB +	\
-				 MINSTREL_CCK_GROUPS_NB)
+				 MINSTREL_LEGACY_GROUPS_NB)
 
 #define MINSTREL_HT_GROUP_0	0
 #define MINSTREL_CCK_GROUP	(MINSTREL_HT_GROUP_0 + MINSTREL_HT_GROUPS_NB)
-#define MINSTREL_VHT_GROUP_0	(MINSTREL_CCK_GROUP + 1)
+#define MINSTREL_OFDM_GROUP	(MINSTREL_CCK_GROUP + 1)
+#define MINSTREL_VHT_GROUP_0	(MINSTREL_OFDM_GROUP + 1)
 
 #define MCS_GROUP_RATES		10
 
@@ -37,6 +38,8 @@ struct mcs_group {
 	u16 duration[MCS_GROUP_RATES];
 };
 
+extern const s16 minstrel_cck_bitrates[4];
+extern const s16 minstrel_ofdm_bitrates[8];
 extern const struct mcs_group minstrel_mcs_groups[];
 
 struct minstrel_mcs_group_data {
@@ -99,6 +102,8 @@ struct minstrel_ht_sta {
 	/* current MCS group to be sampled */
 	u8 sample_group;
 
+	u8 band;
+
 	/* Bitfield of supported MCS rates of all groups */
 	u16 supported[MINSTREL_GROUPS_NB];
 
@@ -107,13 +112,9 @@ struct minstrel_ht_sta {
 };
 
 struct minstrel_ht_sta_priv {
-	union {
 	struct minstrel_ht_sta ht;
-		struct minstrel_sta_info legacy;
-	};
 	void *ratelist;
 	void *sample_table;
-	bool is_ht;
 };
 
 void minstrel_ht_add_sta_debugfs(void *priv, void *priv_sta, struct dentry *dir);

net/mac80211/rc80211_minstrel_ht_debugfs.c

@@ -52,7 +52,6 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 
 	for (j = 0; j < MCS_GROUP_RATES; j++) {
 		struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
-		static const int bitrates[4] = { 10, 20, 55, 110 };
 		int idx = i * MCS_GROUP_RATES + j;
 		unsigned int duration;
 
@@ -67,6 +66,9 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 			p += sprintf(p, "VHT%c0 ", htmode);
 			p += sprintf(p, "%cGI ", gimode);
 			p += sprintf(p, "%d  ", mg->streams);
+		} else if (i == MINSTREL_OFDM_GROUP) {
+			p += sprintf(p, "OFDM       ");
+			p += sprintf(p, "1 ");
 		} else {
 			p += sprintf(p, "CCK    ");
 			p += sprintf(p, "%cP  ", j < 4 ? 'L' : 'S');
@@ -84,7 +86,12 @@ minstrel_ht_stats_dump(struct minstrel_ht_sta *mi, int i, char *p)
 		} else if (gflags & IEEE80211_TX_RC_VHT_MCS) {
 			p += sprintf(p, "  MCS%-1u/%1u", j, mg->streams);
 		} else {
-			int r = bitrates[j % 4];
+			int r;
+
+			if (i == MINSTREL_OFDM_GROUP)
+				r = minstrel_ofdm_bitrates[j % 8];
+			else
+				r = minstrel_cck_bitrates[j % 4];
 
 			p += sprintf(p, "   %2u.%1uM", r / 10, r % 10);
 		}
@@ -124,16 +131,8 @@ minstrel_ht_stats_open(struct inode *inode, struct file *file)
 	struct minstrel_ht_sta *mi = &msp->ht;
 	struct minstrel_debugfs_info *ms;
 	unsigned int i;
-	int ret;
 	char *p;
 
-	if (!msp->is_ht) {
-		inode->i_private = &msp->legacy;
-		ret = minstrel_stats_open(inode, file);
-		inode->i_private = msp;
-		return ret;
-	}
-
 	ms = kmalloc(32768, GFP_KERNEL);
 	if (!ms)
 		return -ENOMEM;
@@ -199,7 +198,6 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
 
 	for (j = 0; j < MCS_GROUP_RATES; j++) {
 		struct minstrel_rate_stats *mrs = &mi->groups[i].rates[j];
-		static const int bitrates[4] = { 10, 20, 55, 110 };
 		int idx = i * MCS_GROUP_RATES + j;
 		unsigned int duration;
 
@@ -214,6 +212,8 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
 			p += sprintf(p, "VHT%c0,", htmode);
 			p += sprintf(p, "%cGI,", gimode);
 			p += sprintf(p, "%d,", mg->streams);
+		} else if (i == MINSTREL_OFDM_GROUP) {
+			p += sprintf(p, "OFDM,,1,");
 		} else {
 			p += sprintf(p, "CCK,");
 			p += sprintf(p, "%cP,", j < 4 ? 'L' : 'S');
@@ -231,7 +231,13 @@ minstrel_ht_stats_csv_dump(struct minstrel_ht_sta *mi, int i, char *p)
 		} else if (gflags & IEEE80211_TX_RC_VHT_MCS) {
 			p += sprintf(p, ",MCS%-1u/%1u,", j, mg->streams);
 		} else {
-			int r = bitrates[j % 4];
+			int r;
+
+			if (i == MINSTREL_OFDM_GROUP)
+				r = minstrel_ofdm_bitrates[j % 8];
+			else
+				r = minstrel_cck_bitrates[j % 4];
+
 			p += sprintf(p, ",%2u.%1uM,", r / 10, r % 10);
 		}
 
@@ -274,18 +280,9 @@ minstrel_ht_stats_csv_open(struct inode *inode, struct file *file)
 	struct minstrel_ht_sta *mi = &msp->ht;
 	struct minstrel_debugfs_info *ms;
 	unsigned int i;
-	int ret;
 	char *p;
 
-	if (!msp->is_ht) {
-		inode->i_private = &msp->legacy;
-		ret = minstrel_stats_csv_open(inode, file);
-		inode->i_private = msp;
-		return ret;
-	}
-
 	ms = kmalloc(32768, GFP_KERNEL);
-
 	if (!ms)
 		return -ENOMEM;