[PATCH 4.20 113/117] mt76x02: assure we update gain after scan

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>

commit 4784a3cc3fffd0ba5ef6c7a23980ae0318fc1369 upstream.

Assure that after we initialize dev->cal.low_gain to -1 this
will cause update gain calibration. Otherwise this might or
might not happen depending on value of second bit of low_gain
and values read from registers in mt76x02_phy_adjust_vga_gain().

Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/wireless/mediatek/mt76/mt76x0/main.c |    5 ++++-
 drivers/net/wireless/mediatek/mt76/mt76x0/phy.c  |    3 ++-
 2 files changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/mediatek/mt76/mt76x0/main.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x0/main.c
@@ -139,8 +139,11 @@ void mt76x0_sw_scan_complete(struct ieee
 
 	clear_bit(MT76_SCANNING, &dev->mt76.state);
 
-	if (dev->cal.gain_init_done)
+	if (dev->cal.gain_init_done) {
+		/* Restore AGC gain and resume calibration after scanning. */
+		dev->cal.low_gain = -1;
 		ieee80211_queue_delayed_work(hw, &dev->cal_work, 0);
+	}
 }
 EXPORT_SYMBOL_GPL(mt76x0_sw_scan_complete);
 
--- a/drivers/net/wireless/mediatek/mt76/mt76x0/phy.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x0/phy.c
@@ -834,7 +834,8 @@ mt76x0_phy_update_channel_gain(struct mt
 	low_gain = (dev->cal.avg_rssi_all > mt76x02_get_rssi_gain_thresh(dev)) +
 		   (dev->cal.avg_rssi_all > mt76x02_get_low_rssi_gain_thresh(dev));
 
-	gain_change = (dev->cal.low_gain & 2) ^ (low_gain & 2);
+	gain_change = dev->cal.low_gain < 0 ||
+		      (dev->cal.low_gain & 2) ^ (low_gain & 2);
 	dev->cal.low_gain = low_gain;
 
 	if (!gain_change) {