wifi: rtw89: no HTC field if TX rate might fallback to legacy

Packets containing HTC field with legacy rate could be dropped by AP. If
TX rate of report is lower than MCS2, hardware might fall back rate to
legacy. Therefore, add a checking rule to avoid HTC field in this
situation.
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220826061011.9037-1-pkshih@realtek.com

drivers/net/wireless/realtek/rtw89/core.c

@@ -585,6 +585,7 @@ __rtw89_core_tx_check_he_qos_htc(struct rtw89_dev *rtwdev,
 				 enum btc_pkt_type pkt_type)
 {
 	struct ieee80211_sta *sta = tx_req->sta;
+	struct rtw89_sta *rtwsta = sta_to_rtwsta_safe(sta);
 	struct sk_buff *skb = tx_req->skb;
 	struct ieee80211_hdr *hdr = (void *)skb->data;
 	__le16 fc = hdr->frame_control;
@@ -602,6 +603,9 @@ __rtw89_core_tx_check_he_qos_htc(struct rtw89_dev *rtwdev,
 	if (skb_headroom(skb) < IEEE80211_HT_CTL_LEN)
 		return false;
 
+	if (rtwsta && rtwsta->ra_report.might_fallback_legacy)
+		return false;
+
 	return true;
 }
 

drivers/net/wireless/realtek/rtw89/core.h

@@ -2079,6 +2079,7 @@ struct rtw89_ra_report {
 	struct rate_info txrate;
 	u32 bit_rate;
 	u16 hw_rate;
+	bool might_fallback_legacy;
 };
 
 DECLARE_EWMA(rssi, 10, 16);

drivers/net/wireless/realtek/rtw89/debug.c

@@ -2306,6 +2306,7 @@ static void rtw89_sta_info_get_iter(void *data, struct ieee80211_sta *sta)
 			   he_gi_str[rate->he_gi] : "N/A");
 	else
 		seq_printf(m, "Legacy %d", rate->legacy);
+	seq_printf(m, "%s", rtwsta->ra_report.might_fallback_legacy ? " FB_G" : "");
 	seq_printf(m, "\t(hw_rate=0x%x)", rtwsta->ra_report.hw_rate);
 	seq_printf(m, "\t==> agg_wait=%d (%d)\n", rtwsta->max_agg_wait,
 		   sta->max_rc_amsdu_len);

drivers/net/wireless/realtek/rtw89/phy.c

@@ -14,23 +14,14 @@
 static u16 get_max_amsdu_len(struct rtw89_dev *rtwdev,
 			     const struct rtw89_ra_report *report)
 {
-	const struct rate_info *txrate = &report->txrate;
 	u32 bit_rate = report->bit_rate;
-	u8 mcs;
 
 	/* lower than ofdm, do not aggregate */
 	if (bit_rate < 550)
 		return 1;
 
-	/* prevent hardware rate fallback to G mode rate */
-	if (txrate->flags & RATE_INFO_FLAGS_MCS)
-		mcs = txrate->mcs & 0x07;
-	else if (txrate->flags & (RATE_INFO_FLAGS_VHT_MCS | RATE_INFO_FLAGS_HE_MCS))
-		mcs = txrate->mcs;
-	else
-		mcs = 0;
-
-	if (mcs <= 2)
+	/* avoid AMSDU for legacy rate */
+	if (report->might_fallback_legacy)
 		return 1;
 
 	/* lower than 20M vht 2ss mcs8, make it small */
@@ -1978,6 +1969,7 @@ static void rtw89_phy_c2h_ra_rpt_iter(void *data, struct ieee80211_sta *sta)
 	u8 mode, rate, bw, giltf, mac_id;
 	u16 legacy_bitrate;
 	bool valid;
+	u8 mcs = 0;
 
 	mac_id = RTW89_GET_PHY_C2H_RA_RPT_MACID(c2h->data);
 	if (mac_id != rtwsta->mac_id)
@@ -1994,7 +1986,7 @@ static void rtw89_phy_c2h_ra_rpt_iter(void *data, struct ieee80211_sta *sta)
 			return;
 	}
 
-	memset(ra_report, 0, sizeof(*ra_report));
+	memset(&ra_report->txrate, 0, sizeof(ra_report->txrate));
 
 	switch (mode) {
 	case RTW89_RA_RPT_MODE_LEGACY:
@@ -2010,6 +2002,7 @@ static void rtw89_phy_c2h_ra_rpt_iter(void *data, struct ieee80211_sta *sta)
 		ra_report->txrate.mcs = rate;
 		if (giltf)
 			ra_report->txrate.flags |= RATE_INFO_FLAGS_SHORT_GI;
+		mcs = ra_report->txrate.mcs & 0x07;
 		break;
 	case RTW89_RA_RPT_MODE_VHT:
 		ra_report->txrate.flags |= RATE_INFO_FLAGS_VHT_MCS;
@@ -2017,6 +2010,7 @@ static void rtw89_phy_c2h_ra_rpt_iter(void *data, struct ieee80211_sta *sta)
 		ra_report->txrate.nss = FIELD_GET(RTW89_RA_RATE_MASK_NSS, rate) + 1;
 		if (giltf)
 			ra_report->txrate.flags |= RATE_INFO_FLAGS_SHORT_GI;
+		mcs = ra_report->txrate.mcs;
 		break;
 	case RTW89_RA_RPT_MODE_HE:
 		ra_report->txrate.flags |= RATE_INFO_FLAGS_HE_MCS;
@@ -2028,6 +2022,7 @@ static void rtw89_phy_c2h_ra_rpt_iter(void *data, struct ieee80211_sta *sta)
 			ra_report->txrate.he_gi = NL80211_RATE_INFO_HE_GI_1_6;
 		else
 			ra_report->txrate.he_gi = NL80211_RATE_INFO_HE_GI_3_2;
+		mcs = ra_report->txrate.mcs;
 		break;
 	}
 
@@ -2035,6 +2030,7 @@ static void rtw89_phy_c2h_ra_rpt_iter(void *data, struct ieee80211_sta *sta)
 	ra_report->bit_rate = cfg80211_calculate_bitrate(&ra_report->txrate);
 	ra_report->hw_rate = FIELD_PREP(RTW89_HW_RATE_MASK_MOD, mode) |
 			     FIELD_PREP(RTW89_HW_RATE_MASK_VAL, rate);
+	ra_report->might_fallback_legacy = mcs <= 2;
 	sta->max_rc_amsdu_len = get_max_amsdu_len(rtwdev, ra_report);
 	rtwsta->max_agg_wait = sta->max_rc_amsdu_len / 1500 - 1;
 }