rtw88: 8822c: add tx stbc support under HT mode

Enabling this improves tx performance for long distance transmission.
We used to enable stbc by the rx stbc cap of the associated station.
But rx cap will be masked out in ieee80211_ht_cap_ie_to_sta_ht_cap
if we do not declare tx stbc.
Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210713104524.47101-2-pkshih@realtek.com

drivers/net/wireless/realtek/rtw88/main.c

@@ -1338,6 +1338,8 @@ static void rtw_init_ht_cap(struct rtw_dev *rtwdev,
 
 	if (rtw_chip_has_rx_ldpc(rtwdev))
 		ht_cap->cap |= IEEE80211_HT_CAP_LDPC_CODING;
+	if (rtw_chip_has_tx_stbc(rtwdev))
+		ht_cap->cap |= IEEE80211_HT_CAP_TX_STBC;
 
 	if (efuse->hw_cap.bw & BIT(RTW_CHANNEL_WIDTH_40))
 		ht_cap->cap |= IEEE80211_HT_CAP_SUP_WIDTH_20_40 |

drivers/net/wireless/realtek/rtw88/main.h

@@ -1146,6 +1146,7 @@ struct rtw_chip_info {
 	u8 txgi_factor;
 	bool is_pwr_by_rate_dec;
 	bool rx_ldpc;
+	bool tx_stbc;
 	u8 max_power_index;
 
 	u16 fw_fifo_addr[RTW_FW_FIFO_MAX];
@@ -1959,6 +1960,11 @@ static inline bool rtw_chip_has_rx_ldpc(struct rtw_dev *rtwdev)
 	return rtwdev->chip->rx_ldpc;
 }
 
+static inline bool rtw_chip_has_tx_stbc(struct rtw_dev *rtwdev)
+{
+	return rtwdev->chip->tx_stbc;
+}
+
 static inline void rtw_release_macid(struct rtw_dev *rtwdev, u8 mac_id)
 {
 	clear_bit(mac_id, rtwdev->mac_id_map);

drivers/net/wireless/realtek/rtw88/rtw8822c.c

@@ -5288,6 +5288,7 @@ struct rtw_chip_info rtw8822c_hw_spec = {
 	.bfer_su_max_num = 2,
 	.bfer_mu_max_num = 1,
 	.rx_ldpc = true,
+	.tx_stbc = true,
 
 #ifdef CONFIG_PM
 	.wow_fw_name = "rtw88/rtw8822c_wow_fw.bin",