ath10k: fix max antenna gain unit

Most of the txpower for the ath10k firmware is stored as twicepower (0.5 dB
steps). This isn't the case for max_antenna_gain - which is still expected
by the firmware as dB.

The firmware is converting it from dB to the internal (twicepower)
representation when it calculates the limits of a channel. This can be seen
in tpc_stats when configuring "12" as max_antenna_gain. Instead of the
expected 12 (6 dB), the tpc_stats shows 24 (12 dB).

Tested on QCA9888 and IPQ4019 with firmware 10.4-3.5.3-00057.

Fixes: 02256930 ("ath10k: use proper tx power unit")
Signed-off-by: Sven Eckelmann <seckelmann@datto.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20190611172131.6064-1-sven@narfation.org

drivers/net/wireless/ath/ath10k/mac.c

@@ -1052,7 +1052,7 @@ static int ath10k_monitor_vdev_start(struct ath10k *ar, int vdev_id)
 	arg.channel.min_power = 0;
 	arg.channel.max_power = channel->max_power * 2;
 	arg.channel.max_reg_power = channel->max_reg_power * 2;
-	arg.channel.max_antenna_gain = channel->max_antenna_gain * 2;
+	arg.channel.max_antenna_gain = channel->max_antenna_gain;
 
 	reinit_completion(&ar->vdev_setup_done);
 	reinit_completion(&ar->vdev_delete_done);
@@ -1498,7 +1498,7 @@ static int ath10k_vdev_start_restart(struct ath10k_vif *arvif,
 	arg.channel.min_power = 0;
 	arg.channel.max_power = chandef->chan->max_power * 2;
 	arg.channel.max_reg_power = chandef->chan->max_reg_power * 2;
-	arg.channel.max_antenna_gain = chandef->chan->max_antenna_gain * 2;
+	arg.channel.max_antenna_gain = chandef->chan->max_antenna_gain;
 
 	if (arvif->vdev_type == WMI_VDEV_TYPE_AP) {
 		arg.ssid = arvif->u.ap.ssid;
@@ -3426,7 +3426,7 @@ static int ath10k_update_channel_list(struct ath10k *ar)
 			ch->min_power = 0;
 			ch->max_power = channel->max_power * 2;
 			ch->max_reg_power = channel->max_reg_power * 2;
-			ch->max_antenna_gain = channel->max_antenna_gain * 2;
+			ch->max_antenna_gain = channel->max_antenna_gain;
 			ch->reg_class_id = 0; /* FIXME */
 
 			/* FIXME: why use only legacy modes, why not any

drivers/net/wireless/ath/ath10k/wmi.h

@@ -2066,7 +2066,9 @@ struct wmi_channel {
 	union {
 		__le32 reginfo1;
 		struct {
+			/* note: power unit is 1 dBm */
 			u8 antenna_max;
+			/* note: power unit is 0.5 dBm */
 			u8 max_tx_power;
 		} __packed;
 	} __packed;
@@ -2086,6 +2088,7 @@ struct wmi_channel_arg {
 	u32 min_power;
 	u32 max_power;
 	u32 max_reg_power;
+	/* note: power unit is 1 dBm */
 	u32 max_antenna_gain;
 	u32 reg_class_id;
 	enum wmi_phy_mode mode;