mt76: mt7915: disable RX_HDR_TRANS_SHORT

This patch disables RX_TRANS_SHORT to make MDP to do header translation
when payload less than 8 bytes, hence the (QoS) null data can be encapsulated
to 802.3 format. However, WDS requires (QoS) null data in 802.11 format
to created vlan AP interfaces.
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: lian.chen <lian.chen@mediatek.com>
Signed-off-by: Sujuan Chen <sujuan.chen@mediatek.com>
Signed-off-by: Bo Jiao <Bo.Jiao@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

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

@@ -450,6 +450,9 @@ static void mt7915_mac_init(struct mt7915_dev *dev)
 
 	mt76_rmw_field(dev, MT_MDP_DCR1, MT_MDP_DCR1_MAX_RX_LEN, rx_len);
 
+	if (!is_mt7915(&dev->mt76))
+		mt76_clear(dev, MT_MDP_DCR2, MT_MDP_DCR2_RX_TRANS_SHORT);
+
 	/* enable hardware de-agg */
 	mt76_set(dev, MT_MDP_DCR0, MT_MDP_DCR0_DAMSDU_EN);
 

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

@@ -837,10 +837,6 @@ mt7915_mac_fill_rx(struct mt7915_dev *dev, struct sk_buff *skb)
 	if (!status->wcid || !ieee80211_is_data_qos(fc))
 		return 0;
 
-	/* drop no data frame */
-	if (fc & cpu_to_le16(IEEE80211_STYPE_NULLFUNC))
-		return -EINVAL;
-
 	status->aggr = unicast &&
 		       !ieee80211_is_qos_nullfunc(fc);
 	status->qos_ctl = qos_ctl;

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

@@ -158,6 +158,9 @@ enum offs_rev {
 #define MT_MDP_DCR1			MT_MDP(0x004)
 #define MT_MDP_DCR1_MAX_RX_LEN		GENMASK(15, 3)
 
+#define MT_MDP_DCR2			MT_MDP(0x0e8)
+#define MT_MDP_DCR2_RX_TRANS_SHORT	BIT(2)
+
 #define MT_MDP_BNRCFR0(_band)		MT_MDP(__OFFS(MDP_BNRCFR0) + \
 					       ((_band) << 8))
 #define MT_MDP_RCFR0_MCU_RX_MGMT	GENMASK(5, 4)