recipes-wifi/linux-mt76/files/patches-3.x/0020-mtk-mt76-mt7996-ACS-channel-time-too-long-on-duty-ch.patch

From 1879c122435092c63eb0e8156f6e75d8e147fa13 Mon Sep 17 00:00:00 2001
From: "fancy.liu" <fancy.liu@mediatek.com>
Date: Tue, 14 Nov 2023 10:13:24 +0800
Subject: [PATCH 020/199] mtk: mt76: mt7996: ACS channel time too long on duty
 channel

Step and issue:
1. Set channel to 36 in hostapd config;
2. Bootup;
3. Enable ACS through UCI command and reload;
4. Check hostapd log, channel 36 channel_time is much longer than other channels.

Root cause:
The reset chan_stat condition missed duty channel.

Solution:
When scan start, need to reset chan_stat in each channel switch.

Issue:
There's a chance that the channel time for duty channel is zero in ACS
scan.

Root cause:
The chan_stat may be reset when restore to duty channel.
Mac80211 will notify to hostapd when scan done and then restore to duty
channel.
And mt76 will clear scan flag after restore done.
If hostapd get the chan_stat before channel_restore, will get the
correct channel time;
If hostapd get the chan_stat after channel_restore, will get zero
channel time;

Solution:
When channel switch, will check the mac80211 scan state but not the mt76 scan flag.
Mac80211 scan state will be set in scanning, and will be reset after
scan done and before restore to duty channel.

Signed-off-by: fancy.liu <fancy.liu@mediatek.com>
---
 mac80211.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mac80211.c b/mac80211.c
index 6d47b26d..9df9109f 100644
--- a/mac80211.c
+++ b/mac80211.c
@@ -928,6 +928,7 @@ void mt76_set_channel(struct mt76_phy *phy)
 	struct cfg80211_chan_def *chandef = &hw->conf.chandef;
 	bool offchannel = hw->conf.flags & IEEE80211_CONF_OFFCHANNEL;
 	int timeout = HZ / 5;
+	unsigned long was_scanning = ieee80211_get_scanning(hw);
 
 	wait_event_timeout(dev->tx_wait, !mt76_has_tx_pending(phy), timeout);
 	mt76_update_survey(phy);
@@ -942,7 +943,7 @@ void mt76_set_channel(struct mt76_phy *phy)
 	if (!offchannel)
 		phy->main_chan = chandef->chan;
 
-	if (chandef->chan != phy->main_chan)
+	if (chandef->chan != phy->main_chan || was_scanning)
 		memset(phy->chan_state, 0, sizeof(*phy->chan_state));
 }
 EXPORT_SYMBOL_GPL(mt76_set_channel);
-- 
2.18.0