[PATCH rtw-next v2 3/4] wifi: rtw88: Set AMPDU factor to hardware for RTL8814A

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

Tell the chip the maximum AMPDU size supported by the AP. This greatly
improves the TX speed of RTL8814AU in the 2.4 GHz band. Before: ~90
Mbps. After: ~300 Mbps.

Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
---
v2:
 - Do this only for RTL8814A.
 - Add a comment explaining why this is needed.
---
 drivers/net/wireless/realtek/rtw88/mac80211.c |  2 ++
 drivers/net/wireless/realtek/rtw88/main.c     | 32 +++++++++++++++++++
 drivers/net/wireless/realtek/rtw88/main.h     |  3 ++
 drivers/net/wireless/realtek/rtw88/rtw8814a.c | 11 +++++++
 4 files changed, 48 insertions(+)

diff --git a/drivers/net/wireless/realtek/rtw88/mac80211.c b/drivers/net/wireless/realtek/rtw88/mac80211.c
index 026fbf4ad9cc..77f9fbe1870c 100644
--- a/drivers/net/wireless/realtek/rtw88/mac80211.c
+++ b/drivers/net/wireless/realtek/rtw88/mac80211.c
@@ -396,6 +396,8 @@ static void rtw_ops_bss_info_changed(struct ieee80211_hw *hw,
 			if (rtw_bf_support)
 				rtw_bf_assoc(rtwdev, vif, conf);
 
+			rtw_set_ampdu_factor(rtwdev, vif, conf);
+
 			rtw_fw_beacon_filter_config(rtwdev, true, vif);
 		} else {
 			rtw_leave_lps(rtwdev);
diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c
index 959f56a3cc1a..bc2c1a5a30b3 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -2447,6 +2447,38 @@ void rtw_core_enable_beacon(struct rtw_dev *rtwdev, bool enable)
 	}
 }
 
+void rtw_set_ampdu_factor(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,
+			  struct ieee80211_bss_conf *bss_conf)
+{
+	const struct rtw_chip_ops *ops = rtwdev->chip->ops;
+	struct ieee80211_sta *sta;
+	u8 factor = 0xff;
+
+	if (!ops->set_ampdu_factor)
+		return;
+
+	rcu_read_lock();
+
+	sta = ieee80211_find_sta(vif, bss_conf->bssid);
+	if (!sta) {
+		rcu_read_unlock();
+		rtw_warn(rtwdev, "%s: failed to find station %pM\n",
+			 __func__, bss_conf->bssid);
+		return;
+	}
+
+	if (sta->deflink.vht_cap.vht_supported)
+		factor = u32_get_bits(sta->deflink.vht_cap.cap,
+				      IEEE80211_VHT_CAP_MAX_A_MPDU_LENGTH_EXPONENT_MASK);
+	else if (sta->deflink.ht_cap.ht_supported)
+		factor = sta->deflink.ht_cap.ampdu_factor;
+
+	rcu_read_unlock();
+
+	if (factor != 0xff)
+		ops->set_ampdu_factor(rtwdev, factor);
+}
+
 MODULE_AUTHOR("Realtek Corporation");
 MODULE_DESCRIPTION("Realtek 802.11ac wireless core module");
 MODULE_LICENSE("Dual BSD/GPL");
diff --git a/drivers/net/wireless/realtek/rtw88/main.h b/drivers/net/wireless/realtek/rtw88/main.h
index 02343e059fd9..f410c554da58 100644
--- a/drivers/net/wireless/realtek/rtw88/main.h
+++ b/drivers/net/wireless/realtek/rtw88/main.h
@@ -878,6 +878,7 @@ struct rtw_chip_ops {
 			   u32 antenna_rx);
 	void (*cfg_ldo25)(struct rtw_dev *rtwdev, bool enable);
 	void (*efuse_grant)(struct rtw_dev *rtwdev, bool enable);
+	void (*set_ampdu_factor)(struct rtw_dev *rtwdev, u8 factor);
 	void (*false_alarm_statistics)(struct rtw_dev *rtwdev);
 	void (*phy_calibration)(struct rtw_dev *rtwdev);
 	void (*dpk_track)(struct rtw_dev *rtwdev);
@@ -2272,4 +2273,6 @@ void rtw_update_channel(struct rtw_dev *rtwdev, u8 center_channel,
 void rtw_core_port_switch(struct rtw_dev *rtwdev, struct ieee80211_vif *vif);
 bool rtw_core_check_sta_active(struct rtw_dev *rtwdev);
 void rtw_core_enable_beacon(struct rtw_dev *rtwdev, bool enable);
+void rtw_set_ampdu_factor(struct rtw_dev *rtwdev, struct ieee80211_vif *vif,
+			  struct ieee80211_bss_conf *bss_conf);
 #endif
diff --git a/drivers/net/wireless/realtek/rtw88/rtw8814a.c b/drivers/net/wireless/realtek/rtw88/rtw8814a.c
index cfd35d40d46e..ce8d4e4c6c57 100644
--- a/drivers/net/wireless/realtek/rtw88/rtw8814a.c
+++ b/drivers/net/wireless/realtek/rtw88/rtw8814a.c
@@ -1332,6 +1332,16 @@ static void rtw8814a_cfg_ldo25(struct rtw_dev *rtwdev, bool enable)
 {
 }
 
+/* Without this RTL8814A sends too many frames and (some?) 11n AP
+ * can't handle it, resulting in low TX speed. Other chips seem fine.
+ */
+static void rtw8814a_set_ampdu_factor(struct rtw_dev *rtwdev, u8 factor)
+{
+	factor = min_t(u8, factor, IEEE80211_VHT_MAX_AMPDU_256K);
+
+	rtw_write32(rtwdev, REG_AMPDU_MAX_LENGTH, (8192 << factor) - 1);
+}
+
 static void rtw8814a_false_alarm_statistics(struct rtw_dev *rtwdev)
 {
 	struct rtw_dm_info *dm_info = &rtwdev->dm_info;
@@ -2051,6 +2061,7 @@ static const struct rtw_chip_ops rtw8814a_ops = {
 	.set_antenna		= NULL,
 	.cfg_ldo25		= rtw8814a_cfg_ldo25,
 	.efuse_grant		= rtw8814a_efuse_grant,
+	.set_ampdu_factor	= rtw8814a_set_ampdu_factor,
 	.false_alarm_statistics	= rtw8814a_false_alarm_statistics,
 	.phy_calibration	= rtw8814a_phy_calibration,
 	.cck_pd_set		= rtw8814a_phy_cck_pd_set,
-- 
2.49.0