mt76: mt7615: rework chainmask handling

Move chainmask to struct mt7615_phy and instead of needlessly making the
format similar to values for older chips, make it refer to the actual chain
bits used for the rx/tx path.
This is important for multiple wiphy support, where for a secondary phy,
antenna_mask will start at 0, and chainmask will start at the chain offset
(bit 2)
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/eeprom.c

@@ -125,8 +125,8 @@ static void mt7615_eeprom_parse_hw_cap(struct mt7615_dev *dev)
 	if (!tx_mask || tx_mask > max_nss)
 		tx_mask = max_nss;
 
-	dev->chainmask = tx_mask << 8 | rx_mask;
 	dev->mphy.antenna_mask = BIT(tx_mask) - 1;
+	dev->phy.chainmask = dev->mphy.antenna_mask;
 }
 
 int mt7615_eeprom_get_power_index(struct mt7615_dev *dev,

drivers/net/wireless/mediatek/mt76/mt7615/mcu.c

@@ -1304,6 +1304,7 @@ int mt7615_mcu_set_channel(struct mt7615_phy *phy)
 	struct mt7615_dev *dev = phy->dev;
 	struct cfg80211_chan_def *chandef = &phy->mt76->chandef;
 	int freq1 = chandef->center_freq1, freq2 = chandef->center_freq2;
+	u8 n_chains = hweight8(phy->mt76->antenna_mask);
 	struct {
 		u8 control_chan;
 		u8 center_chan;
@@ -1325,8 +1326,8 @@ int mt7615_mcu_set_channel(struct mt7615_phy *phy)
 	} req = {
 		.control_chan = chandef->chan->hw_value,
 		.center_chan = ieee80211_frequency_to_channel(freq1),
-		.tx_streams = (dev->chainmask >> 8) & 0xf,
-		.rx_streams_mask = dev->mphy.antenna_mask,
+		.tx_streams = n_chains,
+		.rx_streams_mask = n_chains,
 		.center_chan2 = ieee80211_frequency_to_channel(freq2),
 	};
 	int ret;
@@ -1373,6 +1374,8 @@ int mt7615_mcu_set_channel(struct mt7615_phy *phy)
 	if (ret)
 		return ret;
 
+	req.rx_streams_mask = phy->chainmask;
+
 	return __mt76_mcu_send_msg(&dev->mt76, MCU_EXT_CMD_SET_RX_PATH,
 				   &req, sizeof(req), true);
 }

drivers/net/wireless/mediatek/mt76/mt7615/mt7615.h

@@ -90,6 +90,8 @@ struct mt7615_phy {
 	s8 ofdm_sensitivity;
 	s8 cck_sensitivity;
 
+	u16 chainmask;
+
 	u8 rdd_state;
 	int dfs_state;
 };
@@ -101,7 +103,6 @@ struct mt7615_dev {
 	};
 
 	struct mt7615_phy phy;
-	u16 chainmask;
 	u32 vif_mask;
 	u32 omac_mask;