mt76: mt7915: limit minimum twt duration

The minimum twt duration supported by mt7915 is 64 according to hardware
design. Reply station with TWT_SETUP_CMD_DICTATE if min_twt_dur smaller
than 64.
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7915/mac.c

@@ -2654,6 +2654,12 @@ void mt7915_mac_add_twt_setup(struct ieee80211_hw *hw,
 	if (hweight8(msta->twt.flowid_mask) == ARRAY_SIZE(msta->twt.flow))
 		goto unlock;
 
+	if (twt_agrt->min_twt_dur < MT7915_MIN_TWT_DUR) {
+		setup_cmd = TWT_SETUP_CMD_DICTATE;
+		twt_agrt->min_twt_dur = MT7915_MIN_TWT_DUR;
+		goto unlock;
+	}
+
 	flowid = ffs(~msta->twt.flowid_mask) - 1;
 	le16p_replace_bits(&twt_agrt->req_type, flowid,
 			   IEEE80211_TWT_REQTYPE_FLOWID);

drivers/net/wireless/mediatek/mt76/mt7915/mt7915.h

@@ -66,6 +66,7 @@
 
 #define MT7915_MAX_TWT_AGRT		16
 #define MT7915_MAX_STA_TWT_AGRT		8
+#define MT7915_MIN_TWT_DUR 64
 #define MT7915_MAX_QUEUE		(__MT_RXQ_MAX + __MT_MCUQ_MAX + 2)
 
 struct mt7915_vif;