mt76: improve gain adjustment in noisy environments

When switching between low gain (high RSSI) and high gain settings, it
can take a few seconds to adjust to the current environment.
This can lead to short periods of time with extreme packet loss.

When switching from low_gain=1 to low_gain=2, start with the same gain
adjustment value instead of the lowest to avoid spikes of huge numbers
of false CCA events

Also avoid resetting adjustment values on switching between low_gain
values 0 and 1, since it affects only the upper limit of vga adjustment

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

diff --git a/drivers/net/wireless/mediatek/mt76/mt76x2_phy.c b/drivers/net/wireless/mediatek/mt76/mt76x2_phy.c
index 14aedc3..20ffa6a 100644 (file)
--- a/drivers/net/wireless/mediatek/mt76/mt76x2_phy.c
+++ b/drivers/net/wireless/mediatek/mt76/mt76x2_phy.c
@@ -491,7 +491,8 @@ mt76x2_phy_adjust_vga_gain(struct mt76x2_dev *dev)
        dev->cal.false_cca = false_cca;
        if (false_cca > 800 && dev->cal.agc_gain_adjust < limit)
                dev->cal.agc_gain_adjust += 2;
-       else if (false_cca < 10 && dev->cal.agc_gain_adjust > 0)
+       else if ((false_cca < 10 && dev->cal.agc_gain_adjust > 0) ||
+                (dev->cal.agc_gain_adjust >= limit && false_cca < 500))
                dev->cal.agc_gain_adjust -= 2;
        else
                return;
@@ -550,7 +551,8 @@ static void
 mt76x2_phy_update_channel_gain(struct mt76x2_dev *dev)
 {
        u8 *gain = dev->cal.agc_gain_init;
-       u8 gain_delta;
+       u8 low_gain_delta, gain_delta;
+       bool gain_change;
        int low_gain;
        u32 val;
 
@@ -559,13 +561,14 @@ mt76x2_phy_update_channel_gain(struct mt76x2_dev *dev)
        low_gain = (dev->cal.avg_rssi_all > mt76x2_get_rssi_gain_thresh(dev)) +
                   (dev->cal.avg_rssi_all > mt76x2_get_low_rssi_gain_thresh(dev));
 
-       if (dev->cal.low_gain == low_gain) {
+       gain_change = (dev->cal.low_gain & 2) ^ (low_gain & 2);
+       dev->cal.low_gain = low_gain;
+
+       if (!gain_change) {
                mt76x2_phy_adjust_vga_gain(dev);
                return;
        }
 
-       dev->cal.low_gain = low_gain;
-
        if (dev->mt76.chandef.width == NL80211_CHAN_WIDTH_80) {
                mt76_wr(dev, MT_BBP(RXO, 14), 0x00560211);
                val = mt76_rr(dev, MT_BBP(AGC, 26)) & ~0xf;
@@ -578,14 +581,17 @@ mt76x2_phy_update_channel_gain(struct mt76x2_dev *dev)
                mt76_wr(dev, MT_BBP(RXO, 14), 0x00560423);
        }
 
+       if (mt76x2_has_ext_lna(dev))
+               low_gain_delta = 10;
+       else
+               low_gain_delta = 14;
+
        if (low_gain == 2) {
                mt76_wr(dev, MT_BBP(RXO, 18), 0xf000a990);
                mt76_wr(dev, MT_BBP(AGC, 35), 0x08080808);
                mt76_wr(dev, MT_BBP(AGC, 37), 0x08080808);
-               if (mt76x2_has_ext_lna(dev))
-                       gain_delta = 10;
-               else
-                       gain_delta = 14;
+               gain_delta = low_gain_delta;
+               dev->cal.agc_gain_adjust = 0;
        } else {
                mt76_wr(dev, MT_BBP(RXO, 18), 0xf000a991);
                if (dev->mt76.chandef.width == NL80211_CHAN_WIDTH_80)
@@ -594,11 +600,11 @@ mt76x2_phy_update_channel_gain(struct mt76x2_dev *dev)
                        mt76_wr(dev, MT_BBP(AGC, 35), 0x11111116);
                mt76_wr(dev, MT_BBP(AGC, 37), 0x2121262C);
                gain_delta = 0;
+               dev->cal.agc_gain_adjust = low_gain_delta;
        }
 
        dev->cal.agc_gain_cur[0] = gain[0] - gain_delta;
        dev->cal.agc_gain_cur[1] = gain[1] - gain_delta;
-       dev->cal.agc_gain_adjust = 0;
        mt76x2_phy_set_gain_val(dev);
 
        /* clear false CCA counters */